Radiation effects from Fukushima I nuclear accidents
Encyclopedia
The radiation effects from the Fukushima Daiichi nuclear disaster
are the results of release of radioactive isotopes from the crippled Fukushima Daiichi Nuclear Power Plant after the 2011 Tōhoku earthquake and tsunami
. Radioactive material has been released from the Fukushima containment vessels as the result of deliberate venting to reduce gaseous pressure, deliberate discharge of coolant water into the sea, and associated uncontrolled events. Concerns about the possibility of a large scale radiation leak resulted in 20 km exclusion zone being set up around the power plant and people within the 20–30 km zone being advised to stay indoors. Later, the UK, France and some other countries told their nationals to consider leaving Tokyo, in response to fears of spreading radioactive contamination. The Fukushima incident has led to trace amounts of radiation, including iodine-131
and caesium-134/137
, being observed around the world (New York State, Alaska, Hawaii, Oregon, California, Montreal, and Austria). Large amounts of radioactive isotopes have also been released into the Pacific Ocean
.
In March 2011, Japanese officials announced that "radioactive iodine-131 exceeding safety limits for infants had been detected at 18 water-purification plants in Tokyo and five other prefectures". As of July 2011, the Japanese government has been unable to control the spread of radioactive material into the nation’s food. Radioactive material has been detected in a range of produce, including spinach, tea leaves, milk, fish and beef, up to 200 miles from the nuclear plant. Inside the 12-mile evacuation zone around the plant, all farming has been abandoned.
As of August 2011, the crippled Fukushima nuclear plant is still leaking low levels of radiation and areas surrounding it could remain uninhabitable for decades due to high radiation. It could take “more than 20 years before residents could safely return to areas with current radiation readings of 200 millisieverts per year, and a decade for areas at 100 millisieverts per year”.
The incidents are rated at level 7 rating on the International Nuclear Event Scale
. The total amount of iodine-131
and caesium-137
released into the atmosphere has been estimated to exceed 10% of the emissions from the 1986 Chernobyl disaster
. Frank N. von Hippel
, a U.S. scientist, has estimated that the release of radioactivity is about one-tenth that from the Chernobyl disaster
and the contaminated area is also about one-tenth that that of Chernobyl; he also estimates “on the order of 1,000” people will die from cancer as a result of their exposure to radiation from the Fukushima Daiichi disaster. However, other experts give lower estimates of deaths due to radiation exposure and, given that the radiation exposure resulting from the accident for most people living in Fukushima is very small compared to background radiation, it may be impossible to find statistically significant evidence of increases in cancer.
According to a June 2011 report of the International Atomic Energy Agency
(IAEA), at that time no confirmed long term health effects to any person had been reported as a result of radiation exposure from the nuclear accident.
In a leaked TEPCO-report dated June 2011, was revealed, that Plutonium-238, -239, -240, and -241 were released “to the air” from the site during the first 100 hours after the earthquake, the total amount of plutonium was said to be 120 billion Becquerels. The same paper mentioned a release of 7.6 trillion Becquerels of Neptunium-239. As neptunium-239 decays, it becomes plutonium-239. TEPCO made this report for a press conference on June 6, but according to Mochizuki of the Fukushima Diary website, the media knew and “kept concealing the risk for 7 months and kept people exposed”.
According to one expert, the release of radioactivity is about one-tenth that from the Chernobyl disaster
and the contaminated area is also about one-tenth that that of Chernobyl.
and 630 PBq, combining iodine and caesium with IAEA methodology. On 23 April the NSC updated its release estimates, but it did not reestimate the total release, instead giving indicating that 154 TBq of air release were occurring daily as on 5 April.
On 24 August 2011, the Nuclear Safety Commission (NSC) of Japan published the results of the recalculation of the total amount of radioactive materials released into the air during the incident at the Fukushima Daiichi Nuclear Power Station. The total amounts released between 11 March and 5 April were revised downwards to 1.3 x 10^17 Bq for iodine-131 (I-131) and 1.1 x 10^16 Bq for caesium-137 (Cs-137). Earlier estimations were 1.5 x 10^17 Bq and 1.2 x 10^16 Bq.
On 20 September the Japanese government and TEPCO announced the installation of new filters at the reactors 1, 2 and 3 to reduce the release of radioactive materials into the air. Gases from the reactors would be decontaminated before they would be released into the air. In the first half of September 2011 the amount of radioactive substances released from the plant was about 200-million becquerels per hour, according to TEPCO, that was approximately one-four millionths of the level of the initial stages of the accident in March.
report estimated the total amount of I-131 radiation released into the air as of 19 March based on extrapolating data from several days of ideal observation at some of its worldwide CTBTO
radionuclide measuring facilities (Freiburg, Germany; Stockholm, Sweden; Takasaki, Japan and Sacramento, USA) during the first 10 days of the accident. The report's estimates of total I-131 emissions based on these worldwide measuring stations ranged from 10 PBq to 700 PBq. This estimate was 1% to 40% of the 1760 PBq of I-131 estimated to be release at Chernobyl.
A later, 12 April, NISA
and NSC
estimated the total air release of iodine-131
at 130 PBq and 150 PBq, respectively. However, on 23 April, the NSC revised its original estimates of iodine-131 released. The NSC did not estimate the total release size based upon these updated numbers, but estimated a release of 0.14 TBq per hour on 5 April."
On 22 September the results were published of a survey conducted by the Japanese Science Ministry. This survey showed that radioactive iodine was spread not only northwestward but also southwards of the plant. Soil-samples were taken at 2,200 locations, mostly in Fukushima Prefecture, in June and July, and with this a map was created of the radioactive contamination at 14 June. Because the short half-life of 8 days only 400 locations were still positive. This map showed that iodine-131 spread northwest of the plant, just like caesium-137 as indicated on an earlier map. But I-131 was also found south of the plant at relatively high levels, even higher than those of caesium-137 in coastal areas south of the plant. According to the ministry clouds moving southwards apparently caught large amounts of iodine-131 that were emitted at the time. The survey was done to determine the risks for thyroid cancer within the population.
report estimated the total amount of caesium-137 radiation released into the air as of 19 March based on extrapolating data from several days of ideal observation at a handful of worldwide CTBTO
radionuclide measuring facilities. The agency estimated an average being 5,000 TBq daily. Over the course of the disaster, Chernobyl put out a total of 85,000 TBq of caesium-137. However, later reporting on 12 April estimated total caesium releases at 6,100 TBq to 12,000 TBq, respectively by NISA and NSC. On 23 April, NSC updated this number to 0.14 TBq per hour of caesium-137 on 5 April, but did not recalculate the entire release estimate.
was found in the sediment on on the roof of an apartment-building in the city of Yokohama
, south of Tokio, some 250 kilometers from the plant in Fukushima. This first find of Strontium above 100 becquerels per kilogram raised serious concerns that leaked radiation might have spread far further than the Japanese government expected. The find was done by a private agency that conducted the test upon the request of a resident. After this find Yokohama city started an investigating on soil samples collected from areas near the building. The science ministry said, that the source of the Strontium is still unclear.
Earlier in June, university researchers did detect smaller amounts of plutonium in soil outside the plant after they collected samples during filming by NHK.
Another 300,000 tons of relatively less radioactive water had already been reported to have leaked or purposefully pumped into the sea to free room for storage of highly radioactively contaminated water. TEPCO had attempted to contain contaminated water in the harbor near the plant by installing "curtains" to prevent outflow, but now believes this effort was unsuccessful.
According to a report (published 29 October 2011) of the Institute for Radiological Protection and Nuclear Safety in France the pollution of the Pacific Ocean was probably 30 times bigger than TEPCO admitted in May 2011. The French institute calculated, that between 21 March 21 and 15 July around 27.1 quadrillion becquerels (= 27.100.000.000.000.000) entered the ocean, on 8 April 2011 already 82 percent of this unprecedented quantity had flown into the sea. The location of the plant on the coast with very strong currants contributed to the very fast pollution of a large part of the Pacific ocean, the contamination on marine life in remote waters would likely wane from autumn, but the radioactive pollution in the waters on the coastal area of the prefecture Fukushima, northeast of Tokyo will remain significant for a long time, regarding the 30 years half-time
of this Ce-137 isotope
.
. Some contract companies working for TEPCO have opted not to use the higher limit. On 15 March, TEPCO decided to work with a skeleton crew (in the media called the Fukushima 50
) in order to minimize the number of people exposed to radiation.
On 17 March, IAEA reported 17 persons to have suffered deposition of radioactive material on their face; the levels of exposure were too low to warrant hospital treatment. On 22 March, World Nuclear News reported that one worker had received over 100 mSv during "venting work" at Unit 3. An additional 6 had received over 100 mSv, of which for 1 a level of over 150 mSv was reported for unspecified activities on site. On 24 March, three workers were exposed to high levels of radiation which caused two of them to require hospital treatment after radioactive water seeped through their protective clothes while working in unit 3. Based on the dosimeter values, exposures of 170 mSv were estimated, the injuries indicated exposure to 2000 to 6000 mSv around their ankles. They were not wearing protective boots, as their employing firm's safety manuals "did not assume a scenario in which its employees would carry out work standing in water at a nuclear power plant". The amount of the radioactivity of the water was about 3.9 M Bq
per cubic centimetre.
As of 24 March, 19:30 (JST), 17 workers (of which 14 were from plant operator TEPCO) had been exposed to levels of over 100 mSv. By 29 March, the number of workers reported to have been exposed to levels of over 100 mSv had increased to 19. An American physician reported Japanese doctors have considered banking blood for future treatment of workers exposed to radiation. Tepco has started a re-assessment of the approximately 8300 workers and emergency personnel who have been involved in responding to the incident, which has revealed that by 13 July, of the approximately 6700 personnel tested so far, 88 personnel have received between 100 and 150 mSv, 14 have received between 150 and 200 mSv, 3 have received between 200 and 250 mSv, and 6 have received above 250 mSv.
TEPCO has been criticized in providing safety equipment for its workers. After NISA warned TEPCO that workers were sharing dosimeter
s, since most of the devices were lost in the disaster, the utility sent more to the plant. Japanese media has reported that that workers indicate that standard decontamination procedures are not being observed. Others reports suggest that contract workers are given more dangerous work than TEPCO employees. TEPCO is also seeking workers willing to risk high radiation levels for short periods of time in exchange for high pay. Confidential documents acquired by the Japanese Asahi newspaper suggest that TEPCO hid high levels of radioactive contamination from employees in the days following the incident. In particular, the Asahi reported that radiation levels of 300 mSv/h were detected at least twice on 13 March, but that "the workers who were trying to bring the disaster under control at the plant were not informed of the levels."
On 25 March, an analysis of stagnant water in the basement floor of the turbine building of Unit 1 showed heavy contamination.
On 27 March, TEPCO reported stagnant water in the basement of unit 2 (inside the reactor/turbine building complex, but outside the primary containment) was measured at 1000 mSv/h or more, which prompted evacuation. Additional basement and trench area measurements indicated 60 mSv/h in unit 1, "over 1000" mSv/h in unit 2, and 750 mSv/h in unit 3. The report indicated the main source was iodine-134 with a half-life of less than an hour, which resulted in a radioactive iodine concentration 10 million times the normal value in the reactor. TEPCO later retracted its report, stating that the measurements were inaccurate and attributed the error to comparing the isotope responsible, iodine-134
, to normal levels of another isotope. Measurements were then corrected stating that the iodine levels were 100,000 times the normal level. On 28 March, the erroneous radiation measurement caused TEPCO to reevaluate the software used in analysis.
Measurements within the reactor/turbine buildings, but not in the basement and trench areas, were made on 18 April. These robotic measurements indicated up to 49 mSv/h in unit 1 and 57 mSv/h in unit 3. This is substantially lower than the basement and trench readings, but still exceeds safe working levels without constant worker rotation. Inside primary containment, levels are much higher.
By 23 March 2011, neutron radiation had been observed outside the reactors 13 times at the Fukushima I site. While this could indicate ongoing fission
, a recriticality event
was not believed to account for these readings. Based on those readings and TEPCO reports of high levels of chlorine-38, Dr. Ferenc Dalnoki-Veress speculated that transient criticalities may have occurred. However, Edwin Lyman at the Union of Concerned Scientists was skeptical, believing the reports of chlorine-38 to be in error. TEPCO's chlorine-38 report was later retracted. Noting that limited, uncontrolled chain reactions might occur at Fukushima I, a spokesman for the International Atomic Energy Agency (IAEA) “emphasized that the nuclear reactors won’t explode.”
On 15 April, TEPCO reported that nuclear fuel had melted and fallen to the lower containment sections of three of the Fukushima I reactors, including reactor three. The melted material was not expected to breach one of the lower containers, causing a serious radiation release. Instead, the melted fuel was thought to have dispersed uniformly across the lower portions of the containers of reactors No. 1, No. 2 and No. 3, making the resumption of the fission process, known as a "recriticality" most unlikely.
On 19 April, TEPCO estimated that the unit 2 turbine basement contained 25,000 cubic meters of contaminated water. The water was measured to have 3 MBq/cm3 of Cs-137 and 13 MBq/cm3 of I-131, TEPCO characterized this level of contamination as "extremely high." To attempt to prevent leakage to the sea, TEPCO planned to pump the water from the basement to the Centralized Radiation Waste Treatment Facility.
A suspected hole from the melting of fuel in unit 1 has allowed water to leak in an unknown path from unit 1 which has exhibited radiation measurements "as high as 1,120 mSv/h." Radiation measurements of the water in the unit 3 spent fuel pool were reported at 140 kBq of radioactive caesium-134 per cubic centimeter, 150 kBq of caesium-137 per cubic centimeter, and 11 kBq per cubic centimeter of iodine-131 on 10 May.
Small traces of plutonium have been found in the soil near the stricken reactors, repeated examinations of the soil suggest that the plutonium level is similar to the background level caused by atomic bomb tests. As the isotope signature of the plutonium is closer to that of power reactor plutonium, TEPCO suggested that "two samples out of five may be the direct result of the recent incident." The more important thing to look at is the curium
level in the soil, the soil does contain a short-lived isotope (curium-242) which shows that some alpha
emitters have been released in small amounts by the accident. The release of the beta/gamma emitters such as caesium-137 has been far greater. In the short and medium term the effects of the iodine and the caesium release will dominate the effect of the accident on farming and the general public. In common with almost all soils the soil at the reactor site contains uranium
but the concentration of uranium and the isotope signature is suggesting that the uranium is the normal natural uranium in the soil.
Radioactive strontium-89 and strontium-90 were discovered in soil at the plant on 18 April, amounts detected in soil one-half kilometer from the facility ranged from 3.4 to 4400 Bq/kg of dry soil. Strontium remains in soil from above-ground nuclear testing, however, the amounts measured at the facility are approximately 130 times greater than the amount typically associated with previous nuclear testing.
The isotope signature of the release looks very different to that of the Chernobyl accident, the Japanese accident has released much less of the involatile plutonium, minor actinides and fission products than Chernobyl did.
On 31 March, TEPCO reported that it had measured radioactivity in the plant site groundwater which was 10,000 times the government limit. The company did not think that this radiation had spread to drinking water. NISA questioned the radioactivity measurement and TEPCO is re-evaluating it. Some debris around the plant has been found to be highly radioactive, including a concrete fragment emanating 900 mSv/h.
By 29 March iodine-131 levels in seawater 330 m south of a key discharge outlet had reached 138 Bq/ml (3,355 times the legal limit) and by 30 March, iodine-131 concentrations had reached 180 Bq/ml at the same location near the Fukushima Daiichi nuclear plant, 4,385 times the legal limit. The high levels could be linked to a feared overflow of highly radioactive water that appeared to have leaked from the unit 2 turbine building. On 15 April, I-131 radiation levels were 6,500 times the legal limits. On 16 April, TEPCO began dumping zeolite, a mineral "that absorbs radioactive substances, aiming to slow down contamination of the ocean."
On 4 April, it was reported that the "operators of Japan's crippled power plant say they will release more than 10,000 tons of contaminated water into the ocean to make room in their storage tanks for water that is even more radioactive." Measurements taken on 21 April indicated 186 Bq/l measured 34 km from the Fukushima plant, Japanese media reported this level of seawater contamination second only to the Sellafield
nuclear accident.
On 11 May, TEPCO announced it believed it had sealed a leak from unit 3 to sea, TEPCO did not immediately announce the amount of radiation released by the leak. On 13 May, Greenpeace announced that 10 of the 22 seaweed samples it had collected near the plant showed 10,000 Bq/Kg or higher, five times the Japanese standard for food of 2,000 Bq/Kg for iodine-131 and 500 Bq/kg for radioactive caesium.
In addition to the large releases of contaminated water (520 tons and 4,700 TBq) believed to have leaked from unit 2 from mid-March until early April; another release of radioactive water is believed to have contaminated the sea from unit 3, because on 16 May TEPCO announced seawater measurements of 200 Bq per cubic centimeter of caesium-134, 220 Bq per cubic centimeter of caesium-137, and unspecified high levels of iodine shortly after discovering a unit 3 leak.
At two locations 20 kilometer north and south 3 kilometers from the coast TEPCO found strontium-89
and strontium-90
in the seabed soil. The samples were taken on 2 June. Up to 44 becquerels per kilogram of strontium-90 were detected, which has a half-life of 29 years. These isotopes were also found in soil and in seawater immediately after the accident. Samples taken from fish and seafood caught off the coast of Ibaraki and Chiba, did not contain radioactive stontium.
In April, 2011, the United States Department of Energy published projections of the radiation risks over the next year (that is, for the future) for people living in the neighborhood of the plant. Potential exposure could exceed 20 mSv/year (2 rems/year) in some areas up to 50 kilometers from the plant. That is the level at which relocation would be considered in the USA, and it is a level that could cause roughly one extra cancer case in 500 young adults. However, natural radiation levels are higher in some part of the world than the projected level mentioned above, and about 4 people out of 10 can be expected to develop cancer without exposure to radiation. Further, the radiation exposure resulting from the incident for most people living in Fukushima is so small compared to background radiation that it may be impossible to find statistically significant evidence of increases in cancer.
IAEA reported on 14 March that about 150 people in the vicinity of the plant "received monitoring for radiation levels"; 23 of these people were also decontaminated.
At a distance of 30 km (18.6 mi) from the site, radiation of 0.003–0.170 mSv/h was measured to the north-west on 17 March, while it was 0.001–0.005 mSv/h in other directions. Experts said exposure to this amount of radiation for 6 to 7 hours would result in absorption of the maximum level considered safe for one year. On 16 March Japan's ministry of science measured radiation levels of up to 0.33 mSv/h 20 kilometers northwest of the power plant. At some locations around 30 km from the Fukushima plant, the dose rates rose significantly in 24 hours on 16–17 March. In one location from 0.080 to 0.170 mSv/h and in another from 0.026 to 0.095 mSv/h. The levels varied according to the direction from the plant.
Normal background radiation
varies from place to place but delivers a dose equivalent in the vicinity of 2.4 mSv
/year, or about 0.3 µSv/h. For comparison, one chest x-ray is about 0.02 mSv and an abdominal CT scan is supposed to be less than 10 mSv (but it has been reported that some abdominal CT scans can deliver as much as 90 mSv). People can mitigate their exposure to radiation through a variety of protection techniques.
/hour although they were later reported to be at "about twice the normal level". Later, on 15 March 2011, Edano reported that radiation levels were lower and the average radiation dose rate over the whole day was 0.109 μSv/h. The wind direction on 15 March dispersed radiatioactivity away from the land and back over the Pacific Ocean. On 16 March, the Japanese radiation warning system, SPEEDI, indicated high levels of radiation would spread further than 30 km from the plant, but Japanese authorities did not relay the information to citizens because "the location or the amount of radioactive leakage was not specified at the time." From 17 March, IAEA received regular updates on radiation from 46 cities and indicated that they had remained stable and were "well below levels which are dangerous to human health". In hourly measurements of these cities until 20 March, no significant changes were reported.
On 30 March 2011, the IAEA
stated that its operational criteria for evacuation were exceeded in the village of Iitate, Fukushima
, 39 kilometre north-west of Fukushima I, outside the existing 30 kilometre radiation exclusion zone. The IAEA advised the Japanese authorities to carefully assess the situation there. Experts from Kyoto University and Hiroshima University released research, on 11 April, that "soil samples has revealed that as much as 400 times the normal levels of radiation" which "could remain in communities beyond a 30-kilometer radius from the Fukushima" site.
Urine samples taken from 10 children in the capital of Fukushima prefecture, were analyzed in a French laboratory. All of them contained caesium-134. The sample of an eight year old girl contained 1.13 becquerel/liter. The kids were living up to 60 kilometers away from the troubled nuclear power plant. The Fukushima Network for Saving Children urged the Japanese government to check the children in Fukushima. The Japanese non-profit Radiation Effects Research Foundation said that people should not overreact, because there are no reports known of health problems with these levels of radiation.
Marco Kaltofen presented his findings on the releases of radioactive isotopes from the Fukushima accidents at the annual meeting of the American Public Health Association (APHA). Airborne dust contaminated with radioactive particles was released from the reactors into the air. This dust was found in Japanese car filters: they contained cesium-134 and cesium-137, and cobalt at levels as high as 3 nCi total activity per sample. Materials collected during April 2011 from Japan also contained Iodine 131. Soils and settled dusts were collected from outdoor and inside homes, and also from used children's shoes. High levels of cesium were found at the shoelaces. US air filter and dusts samples did not contain hot particles, except for air samples collected in Seattle, WA in April 2011. Dusts particles contaminated with radioactive cesium were found more than 100 miles from the Fukushima-site, and could be detected at the US west coast.
A detailed map of ground radiation contamination within 80 kilometers of the plant, the joint product of the U.S. Department of Energy and the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT), was released on 6 May. The map showed that a belt of contamination, with radiation from 3 to 14.7 MBq caesium-137 per square meter, spread to the northwest of the nuclear plant. For comparison, areas with activity levels with more than 0.55 MBq caesium-137 per square meter were abandoned after the 1986 Chernobyl accident. The village of Iitate and the town of Namie are impacted. Similar data was used to establish a map that would calculate the amount of radiation a person would be exposed to if a person were to stay outdoors for 8 hours per day through 11 March 2012. Scientists preparing this map, as well as earlier maps, targeted a 20 mSv/a dosage target for evacuation. The government's 20 mSv/a target led to the resignation of Toshiso Kosako, a senior nuclear adviser to Japanese Prime Minister Naoto Kan, who stated "I cannot allow this as a scholar," and argued that the target is too high, especially for children; he also criticized the increased limit for plant workers. In response, parents-groups and schools in some smaller towns and cities in Fukushima Prefecture have organized decontamination of soil surrounding schools defying orders from Tokyo asserting that the schools are safe. Eventually, the Fukushima education board plans to replace the soil at 26 schools with the highest radiation levels.
Anomalous "hot spots" have been discovered in areas far beyond the adjacent region. For example, experts cannot explain how radioactive caesium from the reactors at Fukushima end up in Kanagawa more than 300 kilometres (186.4 mi) to the south.
In the first week of September the Ministry of Science published a new map showing radiation levels in
Fukushima and 4 surrounding prefectures, based on the results of an aerial survey. In the map, different colors were used to show the level of radioactivity at locations one meter above the ground.
Up to 307,000 becquerel
s of cesium per kilogram of soil was detected during a survey held in Fukushima City, 60 kilometers away from the crippled reactors on 14 Sept 2011. This was triple the amount for contaminated soil that by Japanese governmental orders should be sealed into concrete. According to "Citizens Against Fukushima Aging Nuclear Power Plants", these readings were comparable to the high levels in special regulated zones where evacuation was required after the Chernobyl accident. They urged the government to designate the area as a hot spot, where residents would need to voluntarily evacuate and be eligible for state assistance. Professor Tomoya Yamauchi of the University of Kobe, in charge of the study, in which soil samples were tested from five locations around the district, noted that the decontamination conducted in some of the areas tested has not yet reduced the radiation to pre-accident levels.
On 18 October 2011 a hot-spot on a public square was found in the city of Kashiwa, Chiba
in the Nedokoyadai district, by a resident walking with a dosimeter. He informed the city-counsel, their first readings went off scale, their Geiger-counter could only measure up to 10 micro-Sieverts per hour. Later measurements by the Chiba environment foundation gave a final result of 57.5 micro-Sieverts per hour. On 21 October the roads around the place were sealed off, and the place was covered with sandbags three meters around. Further investigations and check-ups were planned on 24 October 2011. These investigations showed on 23 October levels up to 276,000 becquerels radioactive cesium per kilogram soil, 30 centimeters below the surface. The first comments of town-officials on the find of 57.7 micro-Sieverts per hour were: that there could not be a link with the Fukushima disaster, but after the find of this large amount of cesium, officials of the science ministry could not deny the possibility that the cause could be found at the Fukushima-site.
In October 2011, radiation levels as high as those in the evacuation zone around Japan's Fukushima nuclear plant have been detected in a Tokyo suburb. Japanese officials said the contamination was linked to the Fukushima nuclear disaster. Contaminations levels “as high as those inside Fukushima's no-go zone have been detected, with officials speculating that the hotspot was created after radioactive caesium carried in rain water became concentrated because of a broken gutter”.
In October 2011 the Japanese Ministry of Science launched a phone hotline to deal with concerns about radiation exposure outside Fukushima Prefecture. Concerned Japanese citizens had been walking with Geiger-counters through their locality in search for all places with raised radiation levels. Whenever a site was found with a radiation dose at one meter above the ground more than one microsievert per hour and higher than nearby areas, this should be mentioned at the hotline. One microsievert per hour is the limit above this topsoil at school playgrounds would be removed, subsidized by the state of Japan. Local governments were asked to carry out simple decontamination works, such as clearing mud from ditches if necessary. When radiation levels would remain more than one microsievert higher than nearby areas even after the cleaning, the ministry offered to help with further decontamination. On the website of the ministry a guideline was posted on how to measure radiation levels in a proper way, how to hold the dosimeter and how long to wait for a proper reading.
In October 2011 hotspots were reported, that were found on the grounds of two elementary schools in Abiko
in the prefecture Chiba
:
Radioactive cesium was found in waste water discharged into Tokio-bay from a cement factory in the prefecture Chiba
east of Tokio. In September and October two water-samples were taken, they measured 1,103 becquerels per liter and 1,054 becquerels per liter respectively.14 to 15 times higher than the limit set by NISA
. Ashes from incinerators in the prefecture constituted the raw material to produce cement. In this process toxic substances are filtered out of the ashes, the water used to clean these filters was discharged into Tokio-bay. On 2 November 2011 this waste water discharge was halted, and the Japanese authorities started a survey on the cesium-contamination of the seawater of Tokyo Bay near the plant.
, Yamanashi
, Nagano, Shizuoka
, Gifu
, and Toyama
were included in this new map of the soil radiation of cesium-134 and cesium-137 of Japan. Contamination between 30,000 up to 100,000 becquerels per square meter was found in Ichinoseki and Oshu
(prefecture Iwate
), in Saku
, Karuizawa and Sakuho (prefecture Nagano, in Tabayama (prefecture Yamanashi
) and elsewhere.
, and even the regions of Chugoku and Shikoku
in western Japan at more than 500 kilometer from the Fukushima-plant. Rain did accumulate the Cesium into the soil. Measured radiation densites per kilogram reached 250 becquerels in eastern Hokkaido, and 25 becquerels in the mountains of western Japan. According to the research-group, these levels decontamination were not high enough to require decontamination. Professor Tetsuzo Yasunari of the University of Nagoya called for a national soil-testing program because of the nationwide spread of radioactive material, and suggested identified hotspots, places with high radiation levels, should be marked with warning signs.
The first study concentrated on Cesium-137. Around the nuclear plant places were found containing up to 40.000 Becquerel/kg, 8 times the governmental safety-limit of 5.000 Becquerel/kg. Places further away are just below this maximum. East and north-east from the plant the soil was contaminated most. North-west and westwards the soil was less contaminated, because of mountain protection.
The second study had a wider scope, and was meant to study the geographic spread of more radioactive isotopes, like tellurium and iodine. Because these isotopes deposit itself into the soil with rain, Norikazu Kinoshita and his colleagues looked after the effect of two specific rain-showers at 15 March and 21 March 2011. The rainfall at 15 March contaminated the grounds around the plant, the second shower transported the radiation far further from the plant, in the direction of Tokyo. According to the authors, the soil should be decontaminated, but when this is found impossible, farming should be limited.
, Kanto
and Kōshin'etsu regions were proven to be contaminated with radioactive caesium. According to the guidelines of the Ministry of Environment
, ashes with 8,000 becquerels per kilogram or lower, could be buried. Ashes with caesium levels between 8,000 and 100,000 becquerels should be secured, and buried in concrete vessels. A survey was done on 410 sites of waste disposal facilities, on how the ash disposal is proceeding. At 22 sites, mainly in the Tokyo Metropolitan area, the ashes with levels under 8000 becquerels could not be buried due to the objections of concerned residents. On 42 sites ashes were found that contained over 8,000 becquerels of caesium, that could not be buried. The ministry made plans to send officials to meetings in the municipalities to explain to the Japanese people that the waste disposal was done safely, and to demonstrate how the disposal of the ashes above 8000 bequerels was conducted.
showed strong variation, but an upward trend in 10 of them on 23 March. No deposition could be determined in 28 of them until 25 March The highest value obtained was in Ibaraki (480 Bq/m2 on 25 March) and Yamagata (750 Bq/m2 on 26 March) for iodine-13. For caesium-137, the highest value were in Yamagata at 150 and 1200 Bq/m2 respectively.
Measurements made by Japan in a number of locations have shown the presence of radionuclide
s in the ground. On 19 March, upland soil levels of 8,100 Bq/kg of Cs-137 and 300,000 Bq/kg of I-131 were reported. One day later, the measured levels were 163,000 Bq/kg of Cs-137 and 1,170,000 Bq/kg of I-131.
, around 75 kilometers south of the nuclear plant, were 24,000 becquerel (Bq)/kg of iodine-131, 12 times more than the limit of 2,000 Bq/kg, and 690 Bq/kg of caesium, 190 Bq/kg above the limit. In four Prefectures (Ibaraki, Totigi, Gunma, Fukushima) distributing of spinach and kakina was restricted as well as milk from Fukushima. On 23 March, similar restrictions were placed on more leafy vegetables (komatsuna
, cabbages) and all flowerhead brassica
s (like cauliflower) in Fukushima, while parsley
and milk distribution was restricted in Ibaraki. On 24 March, IAEA reported that virtually all milk samples and vegetable samples taken in Fukushima and Ibaraki on 18–21 and 16–22 March respectively were above the limit. Samples from Chiba, Ibaraki and Tochigi also had too high levels in celery
, parsley, spinach and other leafy vegetables. In addition, certain samples of beef mainly taken on 27–29 March showed concentrations of iodine-131 and/or caesium-134 and caesium-137 above the regulatory levels.
After the detection of radioactive caesium
above legal limits in Sand lance
s caught off the coast of Ibaraki Prefecture
, the government of the prefecture banned such fishing. On 11 May, caesium levels in tea leaves from a prefecture "just south of Tokyo" were reported to exceed government limits, this was the first agricultural product from Kanagawa Prefecture that exceeded safety limits. In addition to Kanagawa Prefecture, agricultural products from Tochigi and Ibaraki prefectures have also been found to exceed the government limits, for example, pasture grass collected on 5 May, measured 3,480 Bq/kg of radioactive caesium, approximately 11 times the state limit of 300 becquerels. Even into July radioactive beef
was found on sale in eleven prefectures, as far away as Kochi
and Hokkaido
. Authorities explained that until that point testing had only been performed on the skin and exterior of livestock, animal feed and meat cuts had not been checked for radiation previously.
Hay and straw were found contaminated with caesium, 80 kilometers from the reactors, far outside the evacuation-zone. The news of the contamination of foods with radioactive substances leaking from the Fukushima nuclear reactors damaged the mutual trust between local food producers including farmers and consumers. Everywhere in Japan banners and stickers were found with: "Hang in there, Fukushima!", numerous harmful rumors on Fukushima products could be found online. Many rumors that were discriminatory to Fukushima and other messages slandering Fukushima people could be found on the Internet. The source of cesium was found to be rice straw that had been fead to the animal. But a notice of the Japanese government, that was sent to cattle-farmers after the nuclear accident made no mention to the possibility that rice straw could be contaminated with radioactive materials from the plant. Beef from the prefecture Fukushima was taken from the distribution-channels. But health minister Kohei Otsuka, mentioned on 17 July 2011 that this could be not enough. An inspection was set up, testing the urine of all cows, to be able to return those cows that showed levels of radioactive substances higher than the government-set limit to farms so they could be decontaminated feeding safe hay. According to the minister, the Japanese government should try to buy not-contaminated straw and hay in other parts of the country and offering this to the farmers in the affected areas. All transports of beef raised in the prefecture Fukushima was prohibited after 19 July. The meat of some 132 cows was sold to at least 36 of the 47 prefectures of Japan. In more and more places contaminated meat was found.
On 26 July the body-count was more than 2,800 cows fed with caesium-contaminated food, shipped to 46 of the 47 prefectures in Japan, only Okinawa remained free. Part of this beef, that had reached the markets, still needed to be tested. In an attempt to ease consumer-concern the Japanese government promised to impose inspections on all this beef, and to buy the meat back when higher-than-permissible caesium levels were detected during the tests. The government planned to eventually pass on the buy-back costs to TEPCO. The same day the Japanese ministry of agriculture urged farmers and merchants to renounce the use and sale of compost made of manure from cows that may have been fed the contaminated straw. The measure also applied to humus from leaves fallen from trees. After developing guidelines for safety levels of radioactive caesium in compost and humus, this voluntary ban could be lifted.
On 28 July a ban was imposed on all the shipments on cattle from the prefecture Miyagi
. Some 1,031 beasts had been shipped that probably were fed with contaminated rice-straw. After measurements in 6 of them revealed 1,150 becquerels per kilogram, more than twice the governmental set safety level. Because the origins were scattered all over the prefecture, Miyagi became the second prefecture with a ban on all beef cattle shipments. In the year before 11 March about 33,000 cattle were traded from Miyagi.
On 1 August a ban was put on all cattle in the prefecture Iwate
, after 6 cows from two villages were found with heavy levels of caesium. Iwate was the third prefecture where this was decided. Shipments of cattle and meat would only be allowed after examination, and when the level of caesium was below the regulatory standard. In Iwate some 36,000 cattle was produced in a year. All cattle would be checked for radiation exposure before shipment, and the Japanese government asked the prefecture to temporarily reduce the number of shipments to match its inspection capability.
On 3 August, yet another local government in western Japan, the prefecture Shimane, decided to conduct radiation checks on all beef cattle to ease consumer concerns about food safety. Starting from the second week of August all cattle would be tested. Late July at one farm in this prefecture rice-straw was discovered with radioactive caesium levels exceeding the government safety guide. Although all other tests of beef cattle found far lower levels of radioactivity than the government standard, prices of beef from Shimane plummeted and wholesalers avoided all cattle from the prefecture. All processed beef would undergo preliminary screening, and meat registering 250 becquerels per kilogram or more of radioactive caesium – half the government safety level – would be tested further.
The second week of August the prefecture of Fukushima
started with a buy-out of all cattle that could not be sold because the high levels of caesium in the meat. The prefecture decided to buy back all beef cattle that had become too old for shipment due to the shipping suspension in place since July.
On 2 August a group of farmers agreed with the Fukushima prefectural government to set up a consultative body as early as next week to regulate this process. The prefectural government would provide the subsidies needed. There was some delay, because the farmers and the local government could not agree about the prices for the cattle, further negotiations were needed. The problems for the farmers were growing, because they did not know how to protect their cattle from contamination and did not how to feed their cattle. A senior official of the farmers said that the buy-up plan needed to be implemented without any delay.
In response to calls for more support by farmers the Japanese government unfolded on the 5 August 2011 a plan to buy up all beef contaminated with radioactive caesium, that had already reached the distribution chains, as an additional measurement to support beef cattle farmers.
The plan included:
Other measurements were the expansion of subsidies to beef cattle farmers:
On 19 August 2011 was reported, the meat of 4 cows from one Fukushima farm had been found to be contaminated with radioactive caesium in excess of the government-set safety limits. The day after the meat of 5 other cows from this farm was also found to contain radioactive caesium. Because of this the central government on Friday to put off lifting a shipment ban on Fukushima beef. The 9 cows were among a total of over 200 head of cattle shipped from the farm and slaughtered at a facility in Yokohama city between the 11 March nuclear accident and April. The meat of the 9 had been stored by a food producer. The farmer denied feeding the cows contaminated rice straw, in stead he used imported hay that had been stored at another farm.
On 16 September 2011 the results were published of the measurements of radioactive cesium in rice. The results were known of around 60 percent of all test-locations. Radioactive materials were detected in 94 locations, or 4.3 percent of the total. But the highest level detected so far, in Fukushima prefecture, was 136 becquerels per kilogram, about a quarter of the government's safety limit of 500 Becquerel per kilogram. Tests were conducted in 17 prefectures, and were completed in more than half of them. In 22 locations radioactive materials were detected in harvested rice. The highest level measured was 101.6 becquerels per kilogram, or one fifth of the safety limit. Shipments of rice did start in 15 prefectures, including all 52 municipalities in the prefecture Chiba
. In Fukushima shipments of ordinary rice did start in 2 municipalities, and those of early-harvested rice in 20 municipalities.
On 23 September 2011 radioactive caesium in concentrations above the governmental safety limit was found in rice samples collected in an area in the northeastern part of the prefecture Fukushima. Rice-samples taken before the harvest showed 500 becquerels per kilogram in the city of Nihonmatsu. The Japanese government ordered a two way testing procedure of samples taken before and after the harvest. Pre-harvest tests were carried out in nine prefectures in the regions of Tohoku and Kanto. After the find of this high level of cesium, the prefectural government dis increase the number of places to be tested within the city from 38 to about 300. The city of Nihonmatsu held an emergency meeting on 24 September with officials from the prefecture government. The farmers, that already had started harvesting, were ordered to store their crop until the post-harvest tests were available.
On 16 November 630 becquerels per kilogram of radioactive cesium was detected in rice harvested in the Oonami district in Fukushima City.
All rice of the fields nearby was stored and none of this rice had been sold to the market. On 18 November all 154 farmers in the district were asked to suspend all shipments of rice. Tests were ordered on rice samples from all 154 farms in the district. The result of this testing was reported on 25 November: five more farms were found with cesium contaminated rice at a distance of 56 kilometers from the disaster reactors in the Oonami district of Fukushima City, The highest level of cesium detected was 1,270 becquerels per kilogram.
On 28 November 2011 the prefecture of Fukushima reported the find of cesium-contaminated rice, up to 1050 Becquerels per kilogram, in samples of 3 farms in the city Date
at a distance of 50 kilometers from the Fukushima Daiichi reactors. Some 9 kilo's of this crops were already sold locally before this date. Officials tried to find out who bought this rice. Because of this and earlier finds the government of the prefecture Fukushima decided to control more than 2300 farms in the whole district on cesium-contamination. A more precise number was mentioned by the Japanese newspaper The Mainichi Daily News: on 29 November orders were given to 2381 farms in Nihonmatsu and Motomiya to suspend part of their rice shipments. This number added to the already halted shipments at 1941 farms in 4 other districts including Date
, raised the total to 4322 farms.
terminated the use of dried shiitake-mushrooms in school lunches after tests had found radioactive cesium in them up to 350 bcquerels per kilogram. In shiitake mushrooms grown outdoors on wood in a city in the prefecture Ibaraki
, 170 kilometers from the nuclear plant, samples contained 830 becquerels per kilogram of radioactive cesium, exceeding the government's limit of 500 becquerels. Radioactive contaminated shiitake mushrooms, above 500 becquerels per kilogram, were also found in two cities of prefecture Chiba
, therefore restrictions were imposed on the shipments from these cities.
On 29 October the government of the prefecture Fukushima
announced that shiitake mushrooms grown indoors at a farm in Soma
situated at the coast north from the Fukushima Daiichi plant were to be contaminated with radioactive cesium: They contained 850 becquerels per kilogram, and exceeded the national safety-limit of 500-becquerel. The mushrooms were grown on beds made of woodchips mixed with other nutrients. The woodchips in the mushroom-beds sold by the agricultural cooperative of Soma were thought to have caused of the contamination. Since 24 October 2011 this farm had shipped 1,070 100-gram packages of shiitake mushrooms to nine supermarkets. Besides these no other shiitake mushrooms produced by the farm were sold to customers.
In the city of Yokohama
in March and October food was served to 800 people with dried shiitake
-mushrooms that came from a farm near this town at a distance of 250 kilometer from Fukushima. The test-results of these mushrooms showed 2,770 Becquerels per kilo in March and 955 Becquerels per kilo in October, far above the limit of 500 Becquerels per kilo set by the Japanese government. The mushrooms were checked for contamination in the first week of November, after requests of concerned people with questions about possible contamination of the food served. No mushrooms were sold elsewhere.
On 10 November 2011 some 120 kilometers away southwest from the Fukushima-reactors in the prefecture Tochigi
649 becquerels of radioactive cesium per kilogram was measured in kuritake mushrooms. Four other cities of Tochigi did already stop with the sales and shipments of the mushrooms grown there. The farmers were asked to stop all shipments and to call back the mushrooms already on the market.
in Tokyo, as well as Tochigi
, Gunma, Chiba
and Saitama
prefectures. IAEA reported on 24 March that drinking water in Tokyo, Fukushima and Ibaraki had been above regulatory limits between 16 and 21 March. On 26 March, IAEA reported that the values were now within legal limits. On 23 March, Tokyo drinking water exceeded the safe level for infants, prompting the government to distribute bottled water to families with infants. Measured levels were caused by iodine-131
(I-131) and were 103, 137 and 174 Bq/l. On 24 March, iodine-131 was detected in 12 of 47 prefectures, of which the level in Tochigi was the highest at 110 Bq/kg. Caesium-137 was detected in 6 prefectures but always below 10 Bq/kg. On 25 March, tap water was reported to have reduced to 79 Bq/kg and to be safe for infants in Tokyo and Chiba but still exceeded limits in Hitachi and Tokaimura. On 27 April, "radiation in Tokyo’s water supply fell to undetectable levels for the first time since 18 March."
The following graphs show Iodine-131 water contaminations measured in water purifying plants From 16 March to 7 April:
On 2 July samples of tapwater taken in Tokyo Shinjuku ward radioactive caesium-137 was detected for the first time since April. The concentration was 0.14 becquerel per kilogram and none was discovered yesterday, which compares with 0.21 becquerel on 22 April, according to the Tokyo Metropolitan Institute of Public Health. No caesium-134 or iodine-131 was detected. The level was below the safety limit set by the government. "This is unlikely to be the result of new radioactive materials being introduced, because no other elements were detected, especially the more sensitive iodine," into the water supply, were the comments of Hironobu Unesaki, a nuclear engineering professor at Kyoto University.
were found in the breast milk
of women living east of Tokyo
. However, the levels were below the safety limits for tap water consumption by infants.
exposure to radiation with radioactive iodine
, although in all cases the amounts of radiation did not warrant further examination, according to the Nuclear Safety Commission
on Tuesday 5 July. In October 2011, hormonal
irregularies in 10 evacuated children were reported. However, the organization responsible for the study said that no link had been established between the children's condition and explosure to radiation.
On 9 October a survey started in the prefecture Fukushima: ultrasonic examinations were done of the thyroid glands of all 360.000 children between 0 to 18 years of age. Follow-up tests will be done for the rest of their lives. This was done in response to concerned parents, alarmed by the evidence showing increased incidence of thyroid cancer among children after the 1986 Chernobyl disaster. The project was done by the Medical University of Fukushima. The results of the tests will be mailed to the children within a month. At the end of 2014 the initial testing of all children should be completed, after this the children will undergo a thyroid checkup every 2 years until they turn 20, and once every 5 years above that age.
In November 2011 in urine-samples of 1500 pre-school-children (ages 6 years or younger) from the city of Minamisoma in the prefecture Fukushima radioactive cesium was found in 104 cases. Most had levels between 20 and 30 becquerels per liter, just above the detection limit, but 187 becquerels was found in the urine of a one-year-old baby boy. All was done because the parents were afraid for internal exposure. Local governments only covered the tests for elementary schoolchildren and older students. According to RHC JAPAN a medical consultancy firm in Tokyo, these levels could not harm the health of the children. But director Makoto Akashi of the National Institute of Radiological Sciences said, that although those test results should be verified, this still proved the possibility of internal exposure in the children of Fukushima, but that the internal exposure would not increase, when all food was tested for radioactivity before consumption.
urged detailed checks on wild plants and animals. Radioactive caesium in soil and fallen leaves in forests in his opinion would be easily absorbed by mushrooms and edible plants. He said that wild animals like boars were bound to accumulate high levels of radiation by eating contaminated mushrooms and plants. The professor added that detailed studies were needed on wild plants and animals. Across Europe the Chernobyl-incident had likewise effects on wild fauna and flora.
city in Juli 2011 by scientists of the Tokyo University of Marine Science and Technology. Up to 669 becquerels per kilogram of radioactive cesium was measured in samples of animal plankton taken 3 kilometers offshore. The leader of the research-group Professor Takashi Ishimaru, said that the sea current continuously carried contaminated water southwards from the plant. Further studies to determine the effect on the food-chain and fish would be needed.
: 10 becquerels per liter.
The survey by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) reveals that radioactive cesium released from Fukushima I Nuclear Power Plant reached the ocean 2000 kilometers from the plant and 5000 meters deep one month after the accident. It is considered that airborne cesium particles fell on the ocean surface, and sank as they were attached to the bodies of dead plankton. The survey result was announced in a symposium held on November 20 in Tokyo. From April 18 to 30, JAMSTEC collected "marine snow", sub-millimeter particles made mostly of dead plankton and sand, off the coast of Kamchatka Peninsula, 2000 kilometers away from Fukushima, and off the coast of Ogasawara Islands, 1000 kilometers away, at 5000 meters below the ocean surface. The Agency detected radioactive cesium in both locations, and from the ratio of cesium-137 and cesium-134 and other observations it was determined that it was from Fukushima I Nuclear Power Plant. The density of radioactive cesium is still being analyzed, according to the Agency. It has been thus confirmed that radioactive materials in the ocean are moving and spreading not just by ocean currents but by various other means.
predicted that the initial radiation plume
from the stricken Japanese reactors would reach the United States by 18 March. Health and nuclear experts emphasized that radioactive isotopes in the plume will be very diluted, and would have extremely minor health consequences in the United States. A simulation by the Belgian Institute for Space Aeronomy indicated that trace amounts of radioactivity would reach California and Mexico around 19 March. These predictions were tested by a worldwide network of highly sensitive radiative isotope measuring equipment, with the resulting data used to assess any potential impact to human health as well as the status of the reactors in Japan. Consequently, by 18 March radioactive fallout
including isotopes of iodine-131, iodine-132, tellurium-132, iodine-133, caesium-134 and caesium-137 was detected in air filters at the University of Washington, Seattle, USA.
Due to an anticyclone
south of Japan, favorable westerly winds were dominant during most of the first week of the accident, depositing most of the radioactive material out to sea and away from population centers, with some unfavorable wind directions depositing radioactive material over Tokyo. Low-pressure area over Eastern Japan gave less favorable wind directions 21–22 March. Wind shift to north takes place Tuesday midnight. After the shift, the plume would again be pushed out to the sea for the next becoming days. Roughly similar prediction results are presented for the next 36 hours by the Finnish Meteorological Institute. In spite of winds blowing towards Tokyo during 21–22 March, he comments, "From what I've been able to gather from official reports of radioactivity releases from the Fukushima plant, Tokyo will not receive levels of radiation dangerous to human health in the coming days, should emissions continue at current levels."
Norwegian Institute for Air Research have continuous forecasts of the radioactive cloud and its movement. These are based on the FLEXPART model, originally designed for forecasting the spread of radioactivity from the Chernobyl disaster
.
As of 28 April, the Washington State Department of Health, one of the U.S. states nearest Japan, reported that levels of radioactive material from the Fukushima plant had dropped significantly, and were now often below levels that could be detected with standard tests.
warned against consumption of iodine pills without consulting a doctor and also warned against drinking iodine antiseptic solution. The United States Pentagon said troops are receiving potassium iodide
before missions to areas where possible radiation exposure is likely.
The World Health Organisation (WHO) says it has received reports of people being admitted to poison centres around the world after taking iodine tablets in response to fears about harmful levels of radiation coming out of the damaged nuclear power plant in Fukushima.
, the United States Navy dispatched the aircraft carrier and other vessels in the Seventh Fleet to fly a series of helicopter operations. A U.S. military spokesperson said that low-level radiation forced a change of course en route to Sendai. The Reagan and sailors aboard were exposed to "a month's worth of natural background radiation from the sun, rocks or soil" in an hour and the carrier was repositioned. Seventeen sailors were decontaminated after they and their three helicopters were found to have been exposed to low levels of radioactivity.
The aircraft carrier was docked for maintenance at Yokosuka Naval Base
, about 280 kilometres (174 mi) from the plant, when instruments detected radiation at 07:00 JST on 15 March. Rear Admiral Richard Wren stated that the nuclear crisis in Fukushima, 320 kilometres (198.8 mi) from Yokosuka, was too distant to warrant a discussion about evacuating the base. Daily monitoring and some precautionary measures were recommended for Yokosuka and Atsugi bases, such as limiting outdoor activities and securing external ventilation systems. As a precaution, the Washington was pulled out of its Yokosuka port later in the week. The Navy also stopped moving its personnel to Japan.
is easily absorbed by the thyroid
. Persons exposed to releases of I-131 from any source have a higher risk for developing thyroid cancer
or thyroid disease, or both. Iodine-131 has a short half-life
at approximately 8 days, and therefore is an issue mostly in the first weeks after the incident. Children are more vulnerable to I-131 than adults. Increased risk for thyroid neoplasm remains elevated for at least 40 years after exposure. Potassium iodide
tablets prevent iodine-131 absorption by saturating the thyroid with non-radioactive iodine. Japan's Nuclear Safety Commission recommended local authorities to instruct evacuees leaving the 20-kilometre area to ingest stable (not radioactive) iodine. CBS News
reported that the number of doses of potassium iodide available to the public in Japan was inadequate to meet the perceived needs for an extensive radioactive contamination event.
Caesium-137
is also a particular threat because it behaves like potassium
and is taken up by cells throughout the body. Additionally, it has a long, 30-year half-life. Cs-137 can cause acute radiation sickness
, and increase the risk for cancer
because of exposure to high-energy gamma radiation. Internal exposure to Cs-137, through ingestion or inhalation, allows the radioactive material to be distributed in the soft tissues, especially muscle tissue, exposing these tissues to the beta particles and gamma radiation and increasing cancer risk. Prussian blue
helps the body excrete caesium-137.
Strontium-90
behaves like calcium
, and tends to deposit in bone and blood-forming tissue (bone marrow). 20–30% of ingested Sr-90 is absorbed and deposited in the bone. Internal exposure to Sr-90 is linked to bone cancer, cancer of the soft tissue near the bone, and leukemia. Risk of cancer increases with increased exposure to Sr-90.
Plutonium
is also present in the MOX fuel
of the Unit 3 reactor and in spent fuel rods. Officials at the International Atomic Energy Agency say the presence of MOX fuel does not add significantly to the dangers. Plutonium-239
is particularly long-lived and toxic with a half-life of 24,000 years and remains hazardous for tens of thousands of years. Experts commented that the long-term risk associated with plutonium toxicity is "highly dependent on the geochemistry
of the particular site."
As of September 2011, six workers at the Fukushima Daiichi site have exceeded lifetime legal limits for radiation and more than 300 have received significant radiation doses.
As of September 2011, there were no deaths or serious injuries due to direct radiation exposures. Cancer deaths due to accumulated radiation exposures cannot be ruled out, and according to one expert, might be in the order of 100 cases.
Frank N. von Hippel
, a U.S. scientist, has estimated that “on the order of 1,000” people will die from cancer as a result of their exposure to radiation from the Fukushima Daiichi disaster, that is, an increase of 0.1 percent in the incidence of cancer, and much less than the approximately 20,000 people killed directly by the earthquake and tsunami. Because contaminated milk was “interdicted in Japan” the number of (mostly non-fatal) thyroid cancer cases will probably be less than 1 percent of similar cases at Chernobyl. Von Hippel added that “fear of ionizing radiation could have long-term psychological effects on a large portion of the population in the contaminated areas”.
Fukushima Daiichi nuclear disaster
The is a series of equipment failures, nuclear meltdowns, and releases of radioactive materials at the Fukushima I Nuclear Power Plant, following the Tōhoku earthquake and tsunami on 11 March 2011. The plant comprises six separate boiling water reactors originally designed by General Electric ,...
are the results of release of radioactive isotopes from the crippled Fukushima Daiichi Nuclear Power Plant after the 2011 Tōhoku earthquake and tsunami
2011 Tōhoku earthquake and tsunami
The 2011 earthquake off the Pacific coast of Tohoku, also known as the 2011 Tohoku earthquake, or the Great East Japan Earthquake, was a magnitude 9.0 undersea megathrust earthquake off the coast of Japan that occurred at 14:46 JST on Friday, 11 March 2011, with the epicenter approximately east...
. Radioactive material has been released from the Fukushima containment vessels as the result of deliberate venting to reduce gaseous pressure, deliberate discharge of coolant water into the sea, and associated uncontrolled events. Concerns about the possibility of a large scale radiation leak resulted in 20 km exclusion zone being set up around the power plant and people within the 20–30 km zone being advised to stay indoors. Later, the UK, France and some other countries told their nationals to consider leaving Tokyo, in response to fears of spreading radioactive contamination. The Fukushima incident has led to trace amounts of radiation, including iodine-131
Iodine-131
Iodine-131 , also called radioiodine , is an important radioisotope of iodine. It has a radioactive decay half-life of about eight days. Its uses are mostly medical and pharmaceutical...
and caesium-134/137
Caesium-137
Caesium-137 is a radioactive isotope of caesium which is formed as a fission product by nuclear fission.It has a half-life of about 30.17 years, and decays by beta emission to a metastable nuclear isomer of barium-137: barium-137m . Caesium-137 is a radioactive isotope of caesium which is formed...
, being observed around the world (New York State, Alaska, Hawaii, Oregon, California, Montreal, and Austria). Large amounts of radioactive isotopes have also been released into the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
.
In March 2011, Japanese officials announced that "radioactive iodine-131 exceeding safety limits for infants had been detected at 18 water-purification plants in Tokyo and five other prefectures". As of July 2011, the Japanese government has been unable to control the spread of radioactive material into the nation’s food. Radioactive material has been detected in a range of produce, including spinach, tea leaves, milk, fish and beef, up to 200 miles from the nuclear plant. Inside the 12-mile evacuation zone around the plant, all farming has been abandoned.
As of August 2011, the crippled Fukushima nuclear plant is still leaking low levels of radiation and areas surrounding it could remain uninhabitable for decades due to high radiation. It could take “more than 20 years before residents could safely return to areas with current radiation readings of 200 millisieverts per year, and a decade for areas at 100 millisieverts per year”.
The incidents are rated at level 7 rating on the International Nuclear Event Scale
International Nuclear Event Scale
The International Nuclear and Radiological Event Scale was introduced in 1990 by the International Atomic Energy Agency in order to enable prompt communication of safety significance information in case of nuclear accidents....
. The total amount of iodine-131
Iodine-131
Iodine-131 , also called radioiodine , is an important radioisotope of iodine. It has a radioactive decay half-life of about eight days. Its uses are mostly medical and pharmaceutical...
and caesium-137
Caesium-137
Caesium-137 is a radioactive isotope of caesium which is formed as a fission product by nuclear fission.It has a half-life of about 30.17 years, and decays by beta emission to a metastable nuclear isomer of barium-137: barium-137m . Caesium-137 is a radioactive isotope of caesium which is formed...
released into the atmosphere has been estimated to exceed 10% of the emissions from the 1986 Chernobyl disaster
Chernobyl disaster
The Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine , which was under the direct jurisdiction of the central authorities in Moscow...
. Frank N. von Hippel
Frank N. von Hippel
Frank N. von Hippel, Professor and Co-Director, Program on Science and Global Security, Princeton University, Woodrow Wilson School of Public and International Affairs.-Positions held:...
, a U.S. scientist, has estimated that the release of radioactivity is about one-tenth that from the Chernobyl disaster
Chernobyl disaster
The Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine , which was under the direct jurisdiction of the central authorities in Moscow...
and the contaminated area is also about one-tenth that that of Chernobyl; he also estimates “on the order of 1,000” people will die from cancer as a result of their exposure to radiation from the Fukushima Daiichi disaster. However, other experts give lower estimates of deaths due to radiation exposure and, given that the radiation exposure resulting from the accident for most people living in Fukushima is very small compared to background radiation, it may be impossible to find statistically significant evidence of increases in cancer.
Summarised daily events
- On 11 March, Japanese authorities reported that there had been no "release of radiation" from any of the power plants.
- On 12 March, the day after the earthquake, increased levels of iodine-131 and caesium-137 were reported near Unit 1 on the plant site.
- On 13 March, venting to release pressure started at several reactors resulting in the release of radioactive material.
- From 12 to 15 March the people of Namie was evacuated by the local officials to a place in the north of the town. This may have been in an area directly affected by a cloud of radioactive materials from the plants. There are conflicting reports about whether or not the government knew at the time the extent of the danger, or even how much danger there was.
- Chief Cabinet SecretaryChief Cabinet Secretary__notoc__The of Japan is a Minister of State who is responsible for directing the Cabinet Secretariat. The main function of Chief Cabinet Secretary is to coordinate the policies of ministries and agencies in the executive branch...
Yukio EdanoYukio Edanois a Japanese politician of the Democratic Party of Japan and a member of the House of Representatives in the Diet. He was the Chief Cabinet Secretary in the Kan government. On September 12, 2011, he was named as Minister of Economy, Trade and Industry...
announced on 15 March 2011 that radiation rates had been measured as high as 30 mSv/h on the site of the plant between units 2 and 3, as high as 400 mSv/h near unit 3, between it and unit 4, and 100 mSv/h near unit 4. He said, "there is no doubt that unlike in the past, the figures are the level at which human health can be affected." Prime Minister Naoto KanNaoto Kanis a Japanese politician, and former Prime Minister of Japan. In June 2010, then-Finance Minister Kan was elected as the leader of the Democratic Party of Japan and designated Prime Minister by the Diet to succeed Yukio Hatoyama. On 26 August 2011, Kan announced his resignation...
urged people living between 20 and 30 kilometers of the plant to stay indoors, "The danger of further radiation leaks (from the plant) is increasing," Kan warned the public at a press conference, while asking people to "act calmly". A spokesman for Japan's nuclear safety agency said TEPCO had told it that radiation levels in Ibaraki, between Fukushima and Tokyo, had risen but did not pose a health risk. Edano reported that the average radiation dose rate over the whole day was 0.109 μSv/h. 23 out of 150 tested persons living close to the plant were decontaminated
- On 16 March power plant staff were briefly evacuated after smoke rose above the plant and radiation levels measured at the gate increased to 10 mSv/h. Media reported 1,000 mSv/h close to the leaking reactor, with radiation levels subsequently dropping back to 800–600 mSv. Japan's defence ministry criticized the nuclear safety agency and TEPCO after some of its troops were possibly exposed to radiation when working on the site. Japan's ministry of science (MEXT) measured radiation levels of up to 0.33 mSv/h 20 kilometers northwest of the power plant. Japan's Nuclear Safety Commission recommended local authorities to instruct evacuees leaving the 20-kilometre area to ingest stable (not radioactive) iodine.
- On 17 March IAEA radiation monitoring over 47 cities, showed that levels of radiation in Tokyo had not risen. Although at some locations around 30 km from the Fukushima plant, the dose rates had risen significantly in the preceding 24 hours (in one location from 80 to 170 μSv/h and in another from 26 to 95 μSv/h), levels varied according to the direction from the plant. The level of radiation on spinach grown in open air around 75 kilometers south of the nuclear plant had elevated levels of radioactive iodine and caesium
- On 18 March IAEA clarified that, contrary to several news reports, the IAEA had not received any notification from the Japanese authorities of people sickened by radiation contamination.
- On 19 March MEXT said trace amount of radioactive substances was detected in tap waterTap waterTap water is a principal component of "indoor plumbing", which became available in urban areas of the developed world during the last quarter of the 19th century, and common during the mid-20th century...
in Tokyo, as well as TochigiTochigiTochigi can refer to:* Tochigi Prefecture, a Japanese prefecture* Tochigi, Tochigi, a city in Tochigi prefecture, Japan* Tochigi Station, a railroad station in Tochigi city, Japan.* Tochigi S.C., a Japanese soccer club...
, Gunma, ChibaChiba-Places:* Chiba, Chiba, capital city of Chiba Prefecture, Japan* Chiba Prefecture, a sub-national jurisdiction in the Greater Tokyo Area on the eastern coast of Honshū Island, Japan* Chiba Station, a train station in Chiba, Chiba...
and SaitamaSaitama Prefectureis a prefecture of Japan located in the Kantō region of the island of Honshu. The capital is the city of Saitama.This prefecture is part of the Greater Tokyo Area, and most of Saitama's cities can be described as suburbs of Tokyo, to which a large amount of residents commute each day.- History...
prefectures. The Japanese Ministry of Health, Labour and Welfare announced that radiation levels exceeding legal limits had been detected in milk produced in the Fukushima area and in certain vegetables in Ibaraki. Measurements made by Japan in a number of locations have shown the presence of radionuclideRadionuclideA radionuclide is an atom with an unstable nucleus, which is a nucleus characterized by excess energy available to be imparted either to a newly created radiation particle within the nucleus or to an atomic electron. The radionuclide, in this process, undergoes radioactive decay, and emits gamma...
s such as iodine-131Iodine-131Iodine-131 , also called radioiodine , is an important radioisotope of iodine. It has a radioactive decay half-life of about eight days. Its uses are mostly medical and pharmaceutical...
(I-131) and caesium-137Caesium-137Caesium-137 is a radioactive isotope of caesium which is formed as a fission product by nuclear fission.It has a half-life of about 30.17 years, and decays by beta emission to a metastable nuclear isomer of barium-137: barium-137m . Caesium-137 is a radioactive isotope of caesium which is formed...
(Cs-137) on the ground.
- On 23 March, MEXT released new environmental data. Radioactivity readings for soil and pond samples were highest at one location 40 km northwest of the plant. On 19 March, upland soil there contained 28.1 kBqBecquerelThe becquerel is the SI-derived unit of radioactivity. One Bq is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. The Bq unit is therefore equivalent to an inverse second, s−1...
/kg of Cs-137 and 300 kBq/kg of I-131. One day later, these same figures were 163 kBq/kg of Cs-137 and 1,170 kBq/kg of I-131. Cs-137 of 163 kBq/kg is equal to 3,260 kBq/m2.
- On 24 March, three workers were exposed to high levels of radiation which caused two of them to require hospital treatment after radioactive water seeped through their protective clothes while working in unit 3. It rained in Tokyo from 21 March morning to 24. The rain brought radioactive fallout there. In ShinjukuShinjuku, Tokyois one of the 23 special wards of Tokyo, Japan. It is a major commercial and administrative center, housing the busiest train station in the world and the Tokyo Metropolitan Government Building, the administration center for the government of Tokyo.As of 2008, the ward has an estimated population...
, on the research by Tokyo Metropolitan Institute of Public Health, 83900 Bq/m2 of I-131, 6310 Bq/m2 of Cs-134, and 6350 Bq/m2 of Cs-137 were detected for these four days in total as radioactive fallout's, including 24 hours from 20 9:00 AM to 21 9:00 AM.
- On 25 March the German Ministry of the Environment announced that small amounts of radioactive iodine had been observed in three places within the German atmosphere.
- On 26 March, Japan's nuclear safety agency said that radiation for iodine-131 in seawater near the discharge had increased to 1,850 times the limit.
- 27 March: Levels of "over 1000" (the upper limit of the measuring device) and 750 mSv/h were reported from water within unit 2 (but outside the containment structure) and 3 respectively. A statement that this level was "ten million times the normal level" in unit 2 was later retracted and attributed to attributing radioactivity to iodine-134 rather than to a longer living element. Japan's Nuclear and Industrial Safety Agency indicated that "The level of radiation is greater than 1,000 millisieverts. It is certain that it comes from atomic fission [...] But we are not sure how it came from the reactor."
- 29 March: iodine-131 levels in seawater 330m south of a key discharge outlet had reached 138 Bq/ml (3,355 times the legal limit)
- 30 March: iodine-131 concentrations in seawater had reached 180 Bq/ml at a location 330m south of a plant discharge, 4,385 times the legal limit. Tests indicating 3.7 MBq/m2 of Cs-137 caused the IAEA to state that its criteria for evacuation was exceeded in the village of Iitate, FukushimaIitate, Fukushimais a village located in Sōma District, Fukushima, Japan.As of 2003, the village has an estimated population of 6,858 and a density of 29.80 persons per km²...
, outside the existing 30 kilometre radiation exclusion zone.
- On 31 March, IAEA corrected the value of iodine-131 that had been detected in the Iitate village to 20 million Bq/m2. The value that had been announced at a press interview was about 2 million Bq/m2.
- On 1 April, besides leafy vegetables and parsley, also beef with iodine-131 and/or caesium-134 and caesium-137 levels above the regulatory limit were reported.
- 3 April: Health officials report radioactive substances higher than the legal limits were found in mushroomMushroomA mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source. The standard for the name "mushroom" is the cultivated white button mushroom, Agaricus bisporus; hence the word "mushroom" is most often applied to those fungi that...
s. The Japanese government publicly stated that it expected ongoing radioactive materials releases for "months" assuming normal containment measures are used.
- 4 to 10 April TEPCO announced it began dumping 9,100 tons of water that was 100 times the contamination limit from a wastewater treatment plant, dumping would take 6 days.
- 5 April: Fish caught 50 miles off the coast of Japan had radioactivity exceeding safe levels.
- 15 April: Iodine-131 in seawater was measured at 6,500 times the legal limit, while levels of caesium-134 and caesium-137 rose nearly fourfold, possibly due to installation of steel plates meant to reduce the possibility of water into the ocean.
- 18 April: High levels of radioactive strontium-90 were discovered in soil at the plant, prompting the government to begin regularly testing for the element.
- 22 April: The Japanese government asked residents to leave Iitate and four other villages within a month due to radiation levels.
Total emissions
The primary releases of radioactive nuclides have been iodine and caesium; strontium and plutonium have also been found. These elements have been released into the air via steam; and into the water leaking into groundwater or the ocean. The expert who prepared a frequently cited Austrian Meteorological Service report asserted that the "Chernobyl accident emitted much more radioactivity and a wider diversity of radioactive elements than Fukushima Daiichi has so far, but it was iodine and caesium that caused most of the health risk – especially outside the immediate area of the Chernobyl plant." Iodine-131 has a half-life of 8 days while caesium-137 has a half-life of over 30 years. The IAEA has developed a method that weighs the "radiological equivalence" for different elements. TEPCO has published estimates using a simple sum methodology, and using the IAEA weighting methodology. As of 25 April, TEPCO has not released a total water and air release estimate.According to a June 2011 report of the International Atomic Energy Agency
International Atomic Energy Agency
The International Atomic Energy Agency is an international organization that seeks to promote the peaceful use of nuclear energy, and to inhibit its use for any military purpose, including nuclear weapons. The IAEA was established as an autonomous organization on 29 July 1957...
(IAEA), at that time no confirmed long term health effects to any person had been reported as a result of radiation exposure from the nuclear accident.
In a leaked TEPCO-report dated June 2011, was revealed, that Plutonium-238, -239, -240, and -241 were released “to the air” from the site during the first 100 hours after the earthquake, the total amount of plutonium was said to be 120 billion Becquerels. The same paper mentioned a release of 7.6 trillion Becquerels of Neptunium-239. As neptunium-239 decays, it becomes plutonium-239. TEPCO made this report for a press conference on June 6, but according to Mochizuki of the Fukushima Diary website, the media knew and “kept concealing the risk for 7 months and kept people exposed”.
According to one expert, the release of radioactivity is about one-tenth that from the Chernobyl disaster
Chernobyl disaster
The Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine , which was under the direct jurisdiction of the central authorities in Moscow...
and the contaminated area is also about one-tenth that that of Chernobyl.
Air releases
A 12 April report prepared by NISA estimated the total air release of iodine-131 and caesium-137 at between 370 PBqBecquerel
The becquerel is the SI-derived unit of radioactivity. One Bq is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. The Bq unit is therefore equivalent to an inverse second, s−1...
and 630 PBq, combining iodine and caesium with IAEA methodology. On 23 April the NSC updated its release estimates, but it did not reestimate the total release, instead giving indicating that 154 TBq of air release were occurring daily as on 5 April.
On 24 August 2011, the Nuclear Safety Commission (NSC) of Japan published the results of the recalculation of the total amount of radioactive materials released into the air during the incident at the Fukushima Daiichi Nuclear Power Station. The total amounts released between 11 March and 5 April were revised downwards to 1.3 x 10^17 Bq for iodine-131 (I-131) and 1.1 x 10^16 Bq for caesium-137 (Cs-137). Earlier estimations were 1.5 x 10^17 Bq and 1.2 x 10^16 Bq.
On 20 September the Japanese government and TEPCO announced the installation of new filters at the reactors 1, 2 and 3 to reduce the release of radioactive materials into the air. Gases from the reactors would be decontaminated before they would be released into the air. In the first half of September 2011 the amount of radioactive substances released from the plant was about 200-million becquerels per hour, according to TEPCO, that was approximately one-four millionths of the level of the initial stages of the accident in March.
Iodine-131
A widely cited Austrian Meteorological ServiceCentral Institute for Meteorology and Geodynamics
The Central Institute for Meteorology and Geodynamics is the national meteorological and geophysical service of Austria.It is a subordinate agency of the Austrian Federal Ministry for Science and Research...
report estimated the total amount of I-131 radiation released into the air as of 19 March based on extrapolating data from several days of ideal observation at some of its worldwide CTBTO
Comprehensive Nuclear-Test-Ban Treaty Organization
The Comprehensive Nuclear-Test-Ban Treaty Organization is an international organization that will be established upon the entry into force of the Comprehensive Nuclear-Test-Ban Treaty, a Convention that outlaws nuclear test explosions. Its seat will be Vienna, Austria...
radionuclide measuring facilities (Freiburg, Germany; Stockholm, Sweden; Takasaki, Japan and Sacramento, USA) during the first 10 days of the accident. The report's estimates of total I-131 emissions based on these worldwide measuring stations ranged from 10 PBq to 700 PBq. This estimate was 1% to 40% of the 1760 PBq of I-131 estimated to be release at Chernobyl.
A later, 12 April, NISA
Nuclear and Industrial Safety Agency
The is a Japanese nuclear regulatory and oversight branch of the Agency for Natural Resources and Energy under the Ministry of Economy, Trade and Industry. It was created in 2001 during the 2001 Central Government Reform. It has a main office in Kasumigaseki, Chiyoda, Tokyo that works with the...
and NSC
Japanese Nuclear Safety Commission
Japan's is a commission established within the Cabinet of Japan as an independent agency to play the main role in nuclear safety administration. Commissioners are appointed by the Prime Minister of Japan on Diet approval...
estimated the total air release of iodine-131
Iodine-131
Iodine-131 , also called radioiodine , is an important radioisotope of iodine. It has a radioactive decay half-life of about eight days. Its uses are mostly medical and pharmaceutical...
at 130 PBq and 150 PBq, respectively. However, on 23 April, the NSC revised its original estimates of iodine-131 released. The NSC did not estimate the total release size based upon these updated numbers, but estimated a release of 0.14 TBq per hour on 5 April."
On 22 September the results were published of a survey conducted by the Japanese Science Ministry. This survey showed that radioactive iodine was spread not only northwestward but also southwards of the plant. Soil-samples were taken at 2,200 locations, mostly in Fukushima Prefecture, in June and July, and with this a map was created of the radioactive contamination at 14 June. Because the short half-life of 8 days only 400 locations were still positive. This map showed that iodine-131 spread northwest of the plant, just like caesium-137 as indicated on an earlier map. But I-131 was also found south of the plant at relatively high levels, even higher than those of caesium-137 in coastal areas south of the plant. According to the ministry clouds moving southwards apparently caught large amounts of iodine-131 that were emitted at the time. The survey was done to determine the risks for thyroid cancer within the population.
Tellurium 129m
On 31 October the Japanese ministry of Education, Culture, Sports, Science and Technology released a map showing the contamination of radioactive Tellurium 129m within a 100-kilometer radius around the Fukushima No. 1 nuclear plant. The map displayed the concentrations found of Tellurium-129m -- a byproduct of uranium fission -- in the soil at 14 June 2011. High concentrations were discovered northwest of the plant and also at 28 kilometers south near the coast, in the cities of Iwaki, Fukushima Prefecture, and Kitaibaraki, Ibaraki Prefecture. Iodine 131 was also found In the same areas, and most likely the tellurium was deposited at the same time as the iodine. The highest concentration found was 2.66 million becquerels per square meter, two kilometers from the plant in the empty town of Okuma, Tellurium 129m has a half-time of 6 days, so present levels are a very small fraction of the initial contamination. Tellurium has no biological functions, so even when drinks or food were contaminated with it, it would not accumulate in the body, like iodine in the thyroid gland.Caesium-137
On 24 March, the Austrian Meteorological ServiceCentral Institute for Meteorology and Geodynamics
The Central Institute for Meteorology and Geodynamics is the national meteorological and geophysical service of Austria.It is a subordinate agency of the Austrian Federal Ministry for Science and Research...
report estimated the total amount of caesium-137 radiation released into the air as of 19 March based on extrapolating data from several days of ideal observation at a handful of worldwide CTBTO
Comprehensive Nuclear-Test-Ban Treaty Organization
The Comprehensive Nuclear-Test-Ban Treaty Organization is an international organization that will be established upon the entry into force of the Comprehensive Nuclear-Test-Ban Treaty, a Convention that outlaws nuclear test explosions. Its seat will be Vienna, Austria...
radionuclide measuring facilities. The agency estimated an average being 5,000 TBq daily. Over the course of the disaster, Chernobyl put out a total of 85,000 TBq of caesium-137. However, later reporting on 12 April estimated total caesium releases at 6,100 TBq to 12,000 TBq, respectively by NISA and NSC. On 23 April, NSC updated this number to 0.14 TBq per hour of caesium-137 on 5 April, but did not recalculate the entire release estimate.
Strontium 90
On 12 October 2011 a concentration of 195 becquerels/kilogram of Strontium-90Strontium-90
Strontium-90 is a radioactive isotope of strontium, with a half-life of 28.8 years.-Radioactivity:Natural strontium is nonradioactive and nontoxic, but 90Sr is a radioactivity hazard...
was found in the sediment on on the roof of an apartment-building in the city of Yokohama
Yokohama
is the capital city of Kanagawa Prefecture and the second largest city in Japan by population after Tokyo and most populous municipality of Japan. It lies on Tokyo Bay, south of Tokyo, in the Kantō region of the main island of Honshu...
, south of Tokio, some 250 kilometers from the plant in Fukushima. This first find of Strontium above 100 becquerels per kilogram raised serious concerns that leaked radiation might have spread far further than the Japanese government expected. The find was done by a private agency that conducted the test upon the request of a resident. After this find Yokohama city started an investigating on soil samples collected from areas near the building. The science ministry said, that the source of the Strontium is still unclear.
Plutonium isotopes
On September 30th, 2011, the Japanese ministry of Education and Science published the results of a plutonium fallout survey, for which in June and July 50 soil samples were collected from a radius of slightly more than 80 kilometers around the Fukushima Daiichi plant. Plutonium was found in all samples. Highest found activities (Pu-239 and Pu-240 combined) were 15 becquerels per square meters in Fukushima prefecture and 9.4 becquerels in Ibaraki prefecture. Activities of the especially problematic plutonium-241 isotope were not reported, but minimum values can be with some certainty estimated on the basis of the isotope ratio in the reactors, leading to the possibility of contaminations way above 1000 becquerels per square meter.Earlier in June, university researchers did detect smaller amounts of plutonium in soil outside the plant after they collected samples during filming by NHK.
Water releases
On 21 April, TEPCO estimated that 520 tons radioactive water leaked into the sea before leaks in a pit in unit 2 were plugged, releasing 4,700 TBq of total water release (calculated by simple sum, which is inconsistent with the IAEA methodology for mixed nuclide releases) (20,000 times facility's annual limit). TEPCO's detailed estimates were 2,800 TBq of I-131, 940 TBq of Cs-134, 940 TBq of Cs-137.Another 300,000 tons of relatively less radioactive water had already been reported to have leaked or purposefully pumped into the sea to free room for storage of highly radioactively contaminated water. TEPCO had attempted to contain contaminated water in the harbor near the plant by installing "curtains" to prevent outflow, but now believes this effort was unsuccessful.
According to a report (published 29 October 2011) of the Institute for Radiological Protection and Nuclear Safety in France the pollution of the Pacific Ocean was probably 30 times bigger than TEPCO admitted in May 2011. The French institute calculated, that between 21 March 21 and 15 July around 27.1 quadrillion becquerels (= 27.100.000.000.000.000) entered the ocean, on 8 April 2011 already 82 percent of this unprecedented quantity had flown into the sea. The location of the plant on the coast with very strong currants contributed to the very fast pollution of a large part of the Pacific ocean, the contamination on marine life in remote waters would likely wane from autumn, but the radioactive pollution in the waters on the coastal area of the prefecture Fukushima, northeast of Tokyo will remain significant for a long time, regarding the 30 years half-time
Half-time
In some team sports such as association football and rugby, matches are played in two halves. Half-time is the name given to the interval between the two halves of the match...
of this Ce-137 isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
.
Radiation at the plant site
Radiation fluctuated widely on the site after the tsunami and often correlated to fires and explosions on site. Radiation dose rates at one location between reactor units 3 and 4 was measured at 400 mSv/h at 10:22 JST, 13 March, causing experts to urge rapid rotation of emergency crews as a method of limiting exposure to radiation. Dose rates of 1,000 mSv/h were reported (but not confirmed by the IAEA) close to the certain reactor units on 16 March, prompting a temporary evacuation of plant workers, with radiation levels subsequently dropping back to 800–600 mSv/h. At times, radiation monitoring was hampered by a belief that some radiation levels may be higher than 1 Sv/h, but that "authorities say 1,000 millisieverts [per hour] is the upper limit of their measuring devices."Exposure of workers
Prior to the accident, the maximum permissible dose for Japanese nuclear workers was 100 mSv per year, but on 15 March 2011, the Japanese Health and Labor Ministry increased that annual limit to 250 mSv, for emergency situations. This level is below the 500 mSv/year considered acceptable for emergency work by the World Health OrganizationWorld Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...
. Some contract companies working for TEPCO have opted not to use the higher limit. On 15 March, TEPCO decided to work with a skeleton crew (in the media called the Fukushima 50
Fukushima 50
Fukushima 50 is the alias given by the media to a group of employees at the crippled Fukushima I Nuclear Power Plant. Following the 2011 Tōhoku earthquake and tsunami, a related series of nuclear accidents resulted in a serious fire at the plant's unit 4 on 15 March 2011, these 50 employees...
) in order to minimize the number of people exposed to radiation.
On 17 March, IAEA reported 17 persons to have suffered deposition of radioactive material on their face; the levels of exposure were too low to warrant hospital treatment. On 22 March, World Nuclear News reported that one worker had received over 100 mSv during "venting work" at Unit 3. An additional 6 had received over 100 mSv, of which for 1 a level of over 150 mSv was reported for unspecified activities on site. On 24 March, three workers were exposed to high levels of radiation which caused two of them to require hospital treatment after radioactive water seeped through their protective clothes while working in unit 3. Based on the dosimeter values, exposures of 170 mSv were estimated, the injuries indicated exposure to 2000 to 6000 mSv around their ankles. They were not wearing protective boots, as their employing firm's safety manuals "did not assume a scenario in which its employees would carry out work standing in water at a nuclear power plant". The amount of the radioactivity of the water was about 3.9 M Bq
Becquerel
The becquerel is the SI-derived unit of radioactivity. One Bq is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. The Bq unit is therefore equivalent to an inverse second, s−1...
per cubic centimetre.
As of 24 March, 19:30 (JST), 17 workers (of which 14 were from plant operator TEPCO) had been exposed to levels of over 100 mSv. By 29 March, the number of workers reported to have been exposed to levels of over 100 mSv had increased to 19. An American physician reported Japanese doctors have considered banking blood for future treatment of workers exposed to radiation. Tepco has started a re-assessment of the approximately 8300 workers and emergency personnel who have been involved in responding to the incident, which has revealed that by 13 July, of the approximately 6700 personnel tested so far, 88 personnel have received between 100 and 150 mSv, 14 have received between 150 and 200 mSv, 3 have received between 200 and 250 mSv, and 6 have received above 250 mSv.
TEPCO has been criticized in providing safety equipment for its workers. After NISA warned TEPCO that workers were sharing dosimeter
Dosimeter
Dosimeters measure an individual's or an object'sexposure to something in the environment — particularly to a hazard inflicting cumulative impact over long periods of time, or over a lifetime...
s, since most of the devices were lost in the disaster, the utility sent more to the plant. Japanese media has reported that that workers indicate that standard decontamination procedures are not being observed. Others reports suggest that contract workers are given more dangerous work than TEPCO employees. TEPCO is also seeking workers willing to risk high radiation levels for short periods of time in exchange for high pay. Confidential documents acquired by the Japanese Asahi newspaper suggest that TEPCO hid high levels of radioactive contamination from employees in the days following the incident. In particular, the Asahi reported that radiation levels of 300 mSv/h were detected at least twice on 13 March, but that "the workers who were trying to bring the disaster under control at the plant were not informed of the levels."
Radiation within the primary containment of the reactors
Within the primary containment of reactors 1, 2, 3 and 4 strongly varying levels of radiation were reported:| time (JST) | Reactor 1 (Sv/h) | Reactor 2 (Sv/h) | Reactor 3 (Sv/h) | |||
|---|---|---|---|---|---|---|
| Dry Well |
Wet Well (torus) |
Dry Well |
Wet Well (torus) |
Dry Well |
Wet Well (torus) |
|
| , 12:50 | 0.00410 | 31.6 | 84.4 | 2.43 | --- | --- |
| , 7:55–12:35 | 0.00375 | 46.9 | 78.0 | 2.37 | 105 | 5.90 |
| , 15:00–16:00 | 12.0 | 40.0 | 0.625 | 2.13 | 71.7 | 2.00 |
| , 9:10–14:20 | 48.0 | 29.9 | 50.7 | 1.67 | 60.2 | 1.74 |
| , 17:00 | 40.9 | 25.8 | 47.4 | 1.36 | 53.3 | 1.45 |
| , 10:00 | 38.9 | 24.9 | 45.6 | 1.54 | 51.0 | 1.50 |
| , 14:00–16:30 | 37.1 | 24.5 | 45.2 | 1.54 | 38.8 | 1.31 |
| , 9:30–10:00 | 35.1 | 23.6 | 43.4 | 1.49 | 36.1 | 1.40 |
Radiation outside primary containment of the reactors
Outside the primary containment, plant radiation level measurements have also varied significantlyOn 25 March, an analysis of stagnant water in the basement floor of the turbine building of Unit 1 showed heavy contamination.
| Nuclide | Concentration (Bq Becquerel The becquerel is the SI-derived unit of radioactivity. One Bq is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. The Bq unit is therefore equivalent to an inverse second, s−1... /ml) |
|---|---|
| 1.6 | |
| 3.9 | |
| 5.2 | |
| 2.1 | |
| 1.6 | |
| 1.7 | |
| 1.8 | |
| 3.4 |
On 27 March, TEPCO reported stagnant water in the basement of unit 2 (inside the reactor/turbine building complex, but outside the primary containment) was measured at 1000 mSv/h or more, which prompted evacuation. Additional basement and trench area measurements indicated 60 mSv/h in unit 1, "over 1000" mSv/h in unit 2, and 750 mSv/h in unit 3. The report indicated the main source was iodine-134 with a half-life of less than an hour, which resulted in a radioactive iodine concentration 10 million times the normal value in the reactor. TEPCO later retracted its report, stating that the measurements were inaccurate and attributed the error to comparing the isotope responsible, iodine-134
Isotopes of iodine
There are 37 known isotopes of iodine and only one, 127I, is stable. Iodine is thus a monoisotopic element.Its longest-lived radioactive isotope, 129I, has a half-life of 15.7 million years, which is far too short for it to exist as a primordial nuclide...
, to normal levels of another isotope. Measurements were then corrected stating that the iodine levels were 100,000 times the normal level. On 28 March, the erroneous radiation measurement caused TEPCO to reevaluate the software used in analysis.
Measurements within the reactor/turbine buildings, but not in the basement and trench areas, were made on 18 April. These robotic measurements indicated up to 49 mSv/h in unit 1 and 57 mSv/h in unit 3. This is substantially lower than the basement and trench readings, but still exceeds safe working levels without constant worker rotation. Inside primary containment, levels are much higher.
By 23 March 2011, neutron radiation had been observed outside the reactors 13 times at the Fukushima I site. While this could indicate ongoing fission
Nuclear fission
In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts , often producing free neutrons and photons , and releasing a tremendous amount of energy...
, a recriticality event
Criticality accident
A criticality accident, sometimes referred to as an excursion or a power excursion, is an accidental increase of nuclear chain reactions in a fissile material, such as enriched uranium or plutonium...
was not believed to account for these readings. Based on those readings and TEPCO reports of high levels of chlorine-38, Dr. Ferenc Dalnoki-Veress speculated that transient criticalities may have occurred. However, Edwin Lyman at the Union of Concerned Scientists was skeptical, believing the reports of chlorine-38 to be in error. TEPCO's chlorine-38 report was later retracted. Noting that limited, uncontrolled chain reactions might occur at Fukushima I, a spokesman for the International Atomic Energy Agency (IAEA) “emphasized that the nuclear reactors won’t explode.”
On 15 April, TEPCO reported that nuclear fuel had melted and fallen to the lower containment sections of three of the Fukushima I reactors, including reactor three. The melted material was not expected to breach one of the lower containers, causing a serious radiation release. Instead, the melted fuel was thought to have dispersed uniformly across the lower portions of the containers of reactors No. 1, No. 2 and No. 3, making the resumption of the fission process, known as a "recriticality" most unlikely.
On 19 April, TEPCO estimated that the unit 2 turbine basement contained 25,000 cubic meters of contaminated water. The water was measured to have 3 MBq/cm3 of Cs-137 and 13 MBq/cm3 of I-131, TEPCO characterized this level of contamination as "extremely high." To attempt to prevent leakage to the sea, TEPCO planned to pump the water from the basement to the Centralized Radiation Waste Treatment Facility.
A suspected hole from the melting of fuel in unit 1 has allowed water to leak in an unknown path from unit 1 which has exhibited radiation measurements "as high as 1,120 mSv/h." Radiation measurements of the water in the unit 3 spent fuel pool were reported at 140 kBq of radioactive caesium-134 per cubic centimeter, 150 kBq of caesium-137 per cubic centimeter, and 11 kBq per cubic centimeter of iodine-131 on 10 May.
Soil
TEPCO have reported at at three sites 500 meters from the reactors that the caesium-134 and caesium-137 levels in the soil are between 7.1 kBq and 530 kBq per kilo of undried soil.Small traces of plutonium have been found in the soil near the stricken reactors, repeated examinations of the soil suggest that the plutonium level is similar to the background level caused by atomic bomb tests. As the isotope signature of the plutonium is closer to that of power reactor plutonium, TEPCO suggested that "two samples out of five may be the direct result of the recent incident." The more important thing to look at is the curium
Curium
Curium is a synthetic chemical element with the symbol Cm and atomic number 96. This radioactive transuranic element of the actinide series was named after Marie Skłodowska-Curie and her husband Pierre Curie. Curium was first intentionally produced and identified in summer 1944 by the group of...
level in the soil, the soil does contain a short-lived isotope (curium-242) which shows that some alpha
Alpha
Alpha is the first letter of the Greek alphabet. Alpha or ALPHA may also refer to:-Science:*Alpha , the highest ranking individuals in a community of social animals...
emitters have been released in small amounts by the accident. The release of the beta/gamma emitters such as caesium-137 has been far greater. In the short and medium term the effects of the iodine and the caesium release will dominate the effect of the accident on farming and the general public. In common with almost all soils the soil at the reactor site contains uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
but the concentration of uranium and the isotope signature is suggesting that the uranium is the normal natural uranium in the soil.
Radioactive strontium-89 and strontium-90 were discovered in soil at the plant on 18 April, amounts detected in soil one-half kilometer from the facility ranged from 3.4 to 4400 Bq/kg of dry soil. Strontium remains in soil from above-ground nuclear testing, however, the amounts measured at the facility are approximately 130 times greater than the amount typically associated with previous nuclear testing.
The isotope signature of the release looks very different to that of the Chernobyl accident, the Japanese accident has released much less of the involatile plutonium, minor actinides and fission products than Chernobyl did.
On 31 March, TEPCO reported that it had measured radioactivity in the plant site groundwater which was 10,000 times the government limit. The company did not think that this radiation had spread to drinking water. NISA questioned the radioactivity measurement and TEPCO is re-evaluating it. Some debris around the plant has been found to be highly radioactive, including a concrete fragment emanating 900 mSv/h.
Air and direct radiation
Air outside, but near, unit 3 was reported at 70 mSv/h on 26 April. This was down from radiation levels as high as 130 mSv/h near units 1 and 3 in late March. Removal of debris reduced the radiation measurements from localized highs of up to 900 mSv/h to less than 100 mSv/h at all exterior locations near the reactors; however, readings of 160 mSv/h were still measured at the waste treatment facility.Discharge to seawater and contaminated sealife
Results revealed on 22 March from a sample taken by TEPCO about 100 m south of the discharge channel of units 1–4 showed elevated levels of Cs-137, caesium-134 (Cs-134) and I-131. A sample of seawater taken on 22 March 330m south of the discharge channel (30 kilometers off the coast line) had elevated levels of I-131 and Cs-137. Also, north of the plant elevated levels of these ions were found on 22 March (as well as Cs-134, tellurium-129 and tellurium-129m (Te-129m)) although the levels were lower. Samples taken on the 23 March and/or 24 March contained about 80 Bq/mL of iodine-131 (1850 times the statutory limit) and 26 Bq/mL and caesium-137, most likely caused by atmospheric deposition. By 26 and 27 March this level had decreased to 50 Bq/mL (11) iodine-131 and 7 Bq/mL (2.9) caesium-137 (80 times the limit). Hidehiko Nishiyama, a senior NISA official, stated that radionuclides would "be very diluted by the time it gets consumed by fish and seaweed." Above the seawater, IAEA reported "consistently low" dose rates of 0.04–0.1 μSv/h on 27 March.By 29 March iodine-131 levels in seawater 330 m south of a key discharge outlet had reached 138 Bq/ml (3,355 times the legal limit) and by 30 March, iodine-131 concentrations had reached 180 Bq/ml at the same location near the Fukushima Daiichi nuclear plant, 4,385 times the legal limit. The high levels could be linked to a feared overflow of highly radioactive water that appeared to have leaked from the unit 2 turbine building. On 15 April, I-131 radiation levels were 6,500 times the legal limits. On 16 April, TEPCO began dumping zeolite, a mineral "that absorbs radioactive substances, aiming to slow down contamination of the ocean."
- Seawater radionuclide concentration on 29 March 2011:
Nuclide Concentration (Bq BecquerelThe becquerel is the SI-derived unit of radioactivity. One Bq is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. The Bq unit is therefore equivalent to an inverse second, s−1...
/cm3)Regulatory limit (Bq/cm3) Concentration / Regulatory Limit 0.16 40 .0004 130 0.04 3250 31 0.06 517 2.8 0.3 9.3 32 0.09 356 5.0 0.3 17 2.5 0.4 6.3
On 4 April, it was reported that the "operators of Japan's crippled power plant say they will release more than 10,000 tons of contaminated water into the ocean to make room in their storage tanks for water that is even more radioactive." Measurements taken on 21 April indicated 186 Bq/l measured 34 km from the Fukushima plant, Japanese media reported this level of seawater contamination second only to the Sellafield
Sellafield
Sellafield is a nuclear reprocessing site, close to the village of Seascale on the coast of the Irish Sea in Cumbria, England. The site is served by Sellafield railway station. Sellafield is an off-shoot from the original nuclear reactor site at Windscale which is currently undergoing...
nuclear accident.
On 11 May, TEPCO announced it believed it had sealed a leak from unit 3 to sea, TEPCO did not immediately announce the amount of radiation released by the leak. On 13 May, Greenpeace announced that 10 of the 22 seaweed samples it had collected near the plant showed 10,000 Bq/Kg or higher, five times the Japanese standard for food of 2,000 Bq/Kg for iodine-131 and 500 Bq/kg for radioactive caesium.
In addition to the large releases of contaminated water (520 tons and 4,700 TBq) believed to have leaked from unit 2 from mid-March until early April; another release of radioactive water is believed to have contaminated the sea from unit 3, because on 16 May TEPCO announced seawater measurements of 200 Bq per cubic centimeter of caesium-134, 220 Bq per cubic centimeter of caesium-137, and unspecified high levels of iodine shortly after discovering a unit 3 leak.
At two locations 20 kilometer north and south 3 kilometers from the coast TEPCO found strontium-89
Strontium-89
Strontium-89 is an isotope of strontium.It is treated by the body in a similar manner to calcium, and is preferentially deposited metabolically active regions of the bone.It is an artificial radioisotope which is used in treatment of bone cancer...
and strontium-90
Strontium-90
Strontium-90 is a radioactive isotope of strontium, with a half-life of 28.8 years.-Radioactivity:Natural strontium is nonradioactive and nontoxic, but 90Sr is a radioactivity hazard...
in the seabed soil. The samples were taken on 2 June. Up to 44 becquerels per kilogram of strontium-90 were detected, which has a half-life of 29 years. These isotopes were also found in soil and in seawater immediately after the accident. Samples taken from fish and seafood caught off the coast of Ibaraki and Chiba, did not contain radioactive stontium.
Radiation and Nuclide Detection in Japan
Periodic overall reports of the situation in Japan are provided by the United States Department of Energy.In April, 2011, the United States Department of Energy published projections of the radiation risks over the next year (that is, for the future) for people living in the neighborhood of the plant. Potential exposure could exceed 20 mSv/year (2 rems/year) in some areas up to 50 kilometers from the plant. That is the level at which relocation would be considered in the USA, and it is a level that could cause roughly one extra cancer case in 500 young adults. However, natural radiation levels are higher in some part of the world than the projected level mentioned above, and about 4 people out of 10 can be expected to develop cancer without exposure to radiation. Further, the radiation exposure resulting from the incident for most people living in Fukushima is so small compared to background radiation that it may be impossible to find statistically significant evidence of increases in cancer.
Air exposure within 30 kilometers
The zone within 20 km from the plant was evacuated on 12 March, while residents on a distance up to 30 km were advised to stay indoors and were from 25 March subject to voluntary evacuation.IAEA reported on 14 March that about 150 people in the vicinity of the plant "received monitoring for radiation levels"; 23 of these people were also decontaminated.
At a distance of 30 km (18.6 mi) from the site, radiation of 0.003–0.170 mSv/h was measured to the north-west on 17 March, while it was 0.001–0.005 mSv/h in other directions. Experts said exposure to this amount of radiation for 6 to 7 hours would result in absorption of the maximum level considered safe for one year. On 16 March Japan's ministry of science measured radiation levels of up to 0.33 mSv/h 20 kilometers northwest of the power plant. At some locations around 30 km from the Fukushima plant, the dose rates rose significantly in 24 hours on 16–17 March. In one location from 0.080 to 0.170 mSv/h and in another from 0.026 to 0.095 mSv/h. The levels varied according to the direction from the plant.
Normal background radiation
Background radiation
Background radiation is the ionizing radiation constantly present in the natural environment of the Earth, which is emitted by natural and artificial sources.-Overview:Both Natural and human-made background radiation varies by location....
varies from place to place but delivers a dose equivalent in the vicinity of 2.4 mSv
Sievert
The sievert is the International System of Units SI derived unit of dose equivalent radiation. It attempts to quantitatively evaluate the biological effects of ionizing radiation as opposed to just the absorbed dose of radiation energy, which is measured in gray...
/year, or about 0.3 µSv/h. For comparison, one chest x-ray is about 0.02 mSv and an abdominal CT scan is supposed to be less than 10 mSv (but it has been reported that some abdominal CT scans can deliver as much as 90 mSv). People can mitigate their exposure to radiation through a variety of protection techniques.
Most detailed radiation map published by the Japanese government
A detailed map was published by the Ministry of Education, Culture, Sports, Science and Technology and went online on 18 October 2011. The map contains the cesium concentrations and radiation levels caused by the air born radiation from Fukushima nuclear reactor. This website contains both web-based and PDF versions of the maps, providing information by municipality as had been the case previously, but also measurements by district. The maps were intended to help the residents who had called for better information on contamination levels between areas of the same municipalities, use soil and air sample data already released. A grid is laid over a map of most of eastern Japan. Selecting a square in the grid zooms in on that area, at which point users can choose more detailed maps displaying airborne contamination levels, cesium 134 or 137 levels, or total cesium levels. Radiation mapsGround and water contamination within 30 kilometers
The unrecovered bodies of approximately 1,000 quake and tsunami victims within the plant's evacuation zone are believed to be contaminated with dangerous levels of radiation.Air exposure outside of 30 kilometers
Radiation levels in Tokyo on 15 March were at one point measured at 0.809 μSvSievert
The sievert is the International System of Units SI derived unit of dose equivalent radiation. It attempts to quantitatively evaluate the biological effects of ionizing radiation as opposed to just the absorbed dose of radiation energy, which is measured in gray...
/hour although they were later reported to be at "about twice the normal level". Later, on 15 March 2011, Edano reported that radiation levels were lower and the average radiation dose rate over the whole day was 0.109 μSv/h. The wind direction on 15 March dispersed radiatioactivity away from the land and back over the Pacific Ocean. On 16 March, the Japanese radiation warning system, SPEEDI, indicated high levels of radiation would spread further than 30 km from the plant, but Japanese authorities did not relay the information to citizens because "the location or the amount of radioactive leakage was not specified at the time." From 17 March, IAEA received regular updates on radiation from 46 cities and indicated that they had remained stable and were "well below levels which are dangerous to human health". In hourly measurements of these cities until 20 March, no significant changes were reported.
On 30 March 2011, the IAEA
International Atomic Energy Agency
The International Atomic Energy Agency is an international organization that seeks to promote the peaceful use of nuclear energy, and to inhibit its use for any military purpose, including nuclear weapons. The IAEA was established as an autonomous organization on 29 July 1957...
stated that its operational criteria for evacuation were exceeded in the village of Iitate, Fukushima
Iitate, Fukushima
is a village located in Sōma District, Fukushima, Japan.As of 2003, the village has an estimated population of 6,858 and a density of 29.80 persons per km²...
, 39 kilometre north-west of Fukushima I, outside the existing 30 kilometre radiation exclusion zone. The IAEA advised the Japanese authorities to carefully assess the situation there. Experts from Kyoto University and Hiroshima University released research, on 11 April, that "soil samples has revealed that as much as 400 times the normal levels of radiation" which "could remain in communities beyond a 30-kilometer radius from the Fukushima" site.
Urine samples taken from 10 children in the capital of Fukushima prefecture, were analyzed in a French laboratory. All of them contained caesium-134. The sample of an eight year old girl contained 1.13 becquerel/liter. The kids were living up to 60 kilometers away from the troubled nuclear power plant. The Fukushima Network for Saving Children urged the Japanese government to check the children in Fukushima. The Japanese non-profit Radiation Effects Research Foundation said that people should not overreact, because there are no reports known of health problems with these levels of radiation.
Radioactive Dust-particles
On 31 October 2011 a scientist of the Worcester Polytechnic InstituteWorcester Polytechnic Institute
Worcester Polytechnic Institute is a private university located in Worcester, Massachusetts, in the United States.Founded in 1865 in Worcester, WPI was one of the United States' first engineering and technology universities...
Marco Kaltofen presented his findings on the releases of radioactive isotopes from the Fukushima accidents at the annual meeting of the American Public Health Association (APHA). Airborne dust contaminated with radioactive particles was released from the reactors into the air. This dust was found in Japanese car filters: they contained cesium-134 and cesium-137, and cobalt at levels as high as 3 nCi total activity per sample. Materials collected during April 2011 from Japan also contained Iodine 131. Soils and settled dusts were collected from outdoor and inside homes, and also from used children's shoes. High levels of cesium were found at the shoelaces. US air filter and dusts samples did not contain hot particles, except for air samples collected in Seattle, WA in April 2011. Dusts particles contaminated with radioactive cesium were found more than 100 miles from the Fukushima-site, and could be detected at the US west coast.
Ground, water and sewage contamination outside of 30 kilometers
Tests concluded between 10 and 20 April revealed radioactive caesium in amounts of 2.0 and 3.2 kBq/kg in soil from the Tokyo districts of Chiyoda and Koto, respectively On 5 May, government officials announced that radiation levels in Tokyo sewage had spiked in late March. Simple sum measurements of all radioactive isotopes in sewage burned at a Tokyo treatment plant measured 170,000 Bq/kg "in the immediate wake of the Fukushima nuclear crisis. The government announced that the reason for the spike was unclear, but suspected rainwater. The 5 May announcement further clarified that as of 28 April, the radiation level in Tokyo sewage was 16,000 Bq/kg.A detailed map of ground radiation contamination within 80 kilometers of the plant, the joint product of the U.S. Department of Energy and the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT), was released on 6 May. The map showed that a belt of contamination, with radiation from 3 to 14.7 MBq caesium-137 per square meter, spread to the northwest of the nuclear plant. For comparison, areas with activity levels with more than 0.55 MBq caesium-137 per square meter were abandoned after the 1986 Chernobyl accident. The village of Iitate and the town of Namie are impacted. Similar data was used to establish a map that would calculate the amount of radiation a person would be exposed to if a person were to stay outdoors for 8 hours per day through 11 March 2012. Scientists preparing this map, as well as earlier maps, targeted a 20 mSv/a dosage target for evacuation. The government's 20 mSv/a target led to the resignation of Toshiso Kosako, a senior nuclear adviser to Japanese Prime Minister Naoto Kan, who stated "I cannot allow this as a scholar," and argued that the target is too high, especially for children; he also criticized the increased limit for plant workers. In response, parents-groups and schools in some smaller towns and cities in Fukushima Prefecture have organized decontamination of soil surrounding schools defying orders from Tokyo asserting that the schools are safe. Eventually, the Fukushima education board plans to replace the soil at 26 schools with the highest radiation levels.
Anomalous "hot spots" have been discovered in areas far beyond the adjacent region. For example, experts cannot explain how radioactive caesium from the reactors at Fukushima end up in Kanagawa more than 300 kilometres (186.4 mi) to the south.
In the first week of September the Ministry of Science published a new map showing radiation levels in
Fukushima and 4 surrounding prefectures, based on the results of an aerial survey. In the map, different colors were used to show the level of radioactivity at locations one meter above the ground.
- Red: 19 microsieverts per hour or higher. The red band pointed in north-west direction and was more than 30 kilometer long.
- Yellow: radiation between 3.8 to 19 microsievert per hour. This number is equivalent with a year exposure of more than 20 millisieverts. This is the threshold to designate an area into an evacuation zone. The yellow area extended far beyond the evacuation zone already put into place.
- Light green: radiation between 0.5 and one microsieverts per hour. This was still far above the annual level of one millisievert which should cause no harm to people. This zone contained: most of Fukushima Prefecture, southern parts of Miyagi Prefecture, and northern parts of Tochigi and Ibaraki prefectures.
Up to 307,000 becquerel
Becquerel
The becquerel is the SI-derived unit of radioactivity. One Bq is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. The Bq unit is therefore equivalent to an inverse second, s−1...
s of cesium per kilogram of soil was detected during a survey held in Fukushima City, 60 kilometers away from the crippled reactors on 14 Sept 2011. This was triple the amount for contaminated soil that by Japanese governmental orders should be sealed into concrete. According to "Citizens Against Fukushima Aging Nuclear Power Plants", these readings were comparable to the high levels in special regulated zones where evacuation was required after the Chernobyl accident. They urged the government to designate the area as a hot spot, where residents would need to voluntarily evacuate and be eligible for state assistance. Professor Tomoya Yamauchi of the University of Kobe, in charge of the study, in which soil samples were tested from five locations around the district, noted that the decontamination conducted in some of the areas tested has not yet reduced the radiation to pre-accident levels.
On 18 October 2011 a hot-spot on a public square was found in the city of Kashiwa, Chiba
Chiba
-Places:* Chiba, Chiba, capital city of Chiba Prefecture, Japan* Chiba Prefecture, a sub-national jurisdiction in the Greater Tokyo Area on the eastern coast of Honshū Island, Japan* Chiba Station, a train station in Chiba, Chiba...
in the Nedokoyadai district, by a resident walking with a dosimeter. He informed the city-counsel, their first readings went off scale, their Geiger-counter could only measure up to 10 micro-Sieverts per hour. Later measurements by the Chiba environment foundation gave a final result of 57.5 micro-Sieverts per hour. On 21 October the roads around the place were sealed off, and the place was covered with sandbags three meters around. Further investigations and check-ups were planned on 24 October 2011. These investigations showed on 23 October levels up to 276,000 becquerels radioactive cesium per kilogram soil, 30 centimeters below the surface. The first comments of town-officials on the find of 57.7 micro-Sieverts per hour were: that there could not be a link with the Fukushima disaster, but after the find of this large amount of cesium, officials of the science ministry could not deny the possibility that the cause could be found at the Fukushima-site.
In October 2011, radiation levels as high as those in the evacuation zone around Japan's Fukushima nuclear plant have been detected in a Tokyo suburb. Japanese officials said the contamination was linked to the Fukushima nuclear disaster. Contaminations levels “as high as those inside Fukushima's no-go zone have been detected, with officials speculating that the hotspot was created after radioactive caesium carried in rain water became concentrated because of a broken gutter”.
In October 2011 the Japanese Ministry of Science launched a phone hotline to deal with concerns about radiation exposure outside Fukushima Prefecture. Concerned Japanese citizens had been walking with Geiger-counters through their locality in search for all places with raised radiation levels. Whenever a site was found with a radiation dose at one meter above the ground more than one microsievert per hour and higher than nearby areas, this should be mentioned at the hotline. One microsievert per hour is the limit above this topsoil at school playgrounds would be removed, subsidized by the state of Japan. Local governments were asked to carry out simple decontamination works, such as clearing mud from ditches if necessary. When radiation levels would remain more than one microsievert higher than nearby areas even after the cleaning, the ministry offered to help with further decontamination. On the website of the ministry a guideline was posted on how to measure radiation levels in a proper way, how to hold the dosimeter and how long to wait for a proper reading.
In October 2011 hotspots were reported, that were found on the grounds of two elementary schools in Abiko
Abiko, Chiba
is a city located in northern Chiba Prefecture, Japan. As of February 2011, the town had an estimated population of 134,154 and a population density of 3110 persons per km²...
in the prefecture Chiba
Chiba
-Places:* Chiba, Chiba, capital city of Chiba Prefecture, Japan* Chiba Prefecture, a sub-national jurisdiction in the Greater Tokyo Area on the eastern coast of Honshū Island, Japan* Chiba Station, a train station in Chiba, Chiba...
:
- 11.3 microsieverts per hour was detected on 25 September just above the surface of the ground near a ditch in the compounds of the Abiko Municipal Daiichi Elementary School. 50 centimeters above the ground the reading was 1.7 microsieverts per hour. The soil in the ditch contained 60,768 becquerels per kilogram. After the soil was removed the radiation declined to 0.6 microsieverts per hour at 50 centimeters above groundlevel.
- 10.1 microsieverts per hour was found at the Abiko Municipal Namiki Elementary School near the surface of the ground where sludge removed from the swimming pool of the school had been buried. The area was covered with a waterproof tarp and dirt was put on top of the tarp to decrease the radiation, 0.6 microsieverts per hour was measured 50 centimeters above the ground after this was done.
Radioactive cesium was found in waste water discharged into Tokio-bay from a cement factory in the prefecture Chiba
Chiba
-Places:* Chiba, Chiba, capital city of Chiba Prefecture, Japan* Chiba Prefecture, a sub-national jurisdiction in the Greater Tokyo Area on the eastern coast of Honshū Island, Japan* Chiba Station, a train station in Chiba, Chiba...
east of Tokio. In September and October two water-samples were taken, they measured 1,103 becquerels per liter and 1,054 becquerels per liter respectively.14 to 15 times higher than the limit set by NISA
NISA
NISA may refer to:*Nuclear and Industrial Safety Agency, part of the Japanese Ministry of Economy, Trade and Industry*NIS America, the US subsidiary of Nippon Ichi Software...
. Ashes from incinerators in the prefecture constituted the raw material to produce cement. In this process toxic substances are filtered out of the ashes, the water used to clean these filters was discharged into Tokio-bay. On 2 November 2011 this waste water discharge was halted, and the Japanese authorities started a survey on the cesium-contamination of the seawater of Tokyo Bay near the plant.
Cesium-134 & Cesium-137 soil-radiation-map
On 12 November the Japanese government published a radiation map compiled by helicopter. This map covered a much wider area than before. Six new prefectures IwateIwate
Iwate can refer to:* Iwate Prefecture, a prefecture of Japan.* Iwate, Iwate, a town in Iwate Prefecture, Japan.* Japanese cruiser Iwate, an armored cruiser of the Imperial Japanese Navy from 1900 to the end of World War II....
, Yamanashi
Yamanashi Prefecture
is a prefecture of Japan located in the Chūbu region of the island of Honshū. The capital is the city of Kōfu.-Pre-history to the 14th century:People have been living in the Yamanashi area for about 30,000 years...
, Nagano, Shizuoka
Shizuoka Prefecture
is a prefecture of Japan located in the Chūbu region on Honshu island. The capital is the city of Shizuoka.- History :Shizuoka prefecture was formed from the former Tōtōmi, Suruga and Izu provinces.The area was the home of the first Tokugawa Shogun...
, Gifu
Gifu
Gifu may refer to:*Gifu Prefecture, located in the Chūbu region of central Japan*Gifu, Gifu, the capital city of Gifu Prefecture*Gifu , a region located in southcentral Gifu Prefecture*Gifu Castle atop Mt...
, and Toyama
Toyama
Toyama may refer to:* Toyama Prefecture, Japan* Toyama, Toyama, the capital city of the prefecture* Toyama, Shinjuku, the town of Tokyo Metropolis*Kataller Toyama, the capital city's professional football club* Tōyama, a Japanese surname...
were included in this new map of the soil radiation of cesium-134 and cesium-137 of Japan. Contamination between 30,000 up to 100,000 becquerels per square meter was found in Ichinoseki and Oshu
Oshu
Oshu or Ōshū may refer to:* Oshu** Oshu , the First Prime of Lord Yu in New Order .** Ōshū, another name for Mutsu Province.** The city of Ōshū, Iwate, Japan....
(prefecture Iwate
Iwate
Iwate can refer to:* Iwate Prefecture, a prefecture of Japan.* Iwate, Iwate, a town in Iwate Prefecture, Japan.* Japanese cruiser Iwate, an armored cruiser of the Imperial Japanese Navy from 1900 to the end of World War II....
), in Saku
Saku
Saku may refer to:*Saku, Nagano, a city in Japan*Saku, Nagano , a town in Japan*Saku Parish, a rural municipality in Harju County, Estonia**Saku, a small borough in Saku Parish, Harju County, Estonia*Saku Brewery, an Estonian brewery...
, Karuizawa and Sakuho (prefecture Nagano, in Tabayama (prefecture Yamanashi
Yamanashi Prefecture
is a prefecture of Japan located in the Chūbu region of the island of Honshū. The capital is the city of Kōfu.-Pre-history to the 14th century:People have been living in the Yamanashi area for about 30,000 years...
) and elsewhere.
Computer simulations of Cesium contamination
Based on radiation measurements made all over Japan between 20 March and 20 April 2011, and the atmospheric patterns in that period, a computer simulations were preformed by an international team of researchers, in cooperation with the University of Nagoya, in order to estimate the spread of radioactive materials like Cesium-137. Their results, published in two studies on 14 November 2011, did suggest that Cesium-137 did reach up to the northernmost island of HokkaidoHokkaido
, formerly known as Ezo, Yezo, Yeso, or Yesso, is Japan's second largest island; it is also the largest and northernmost of Japan's 47 prefectural-level subdivisions. The Tsugaru Strait separates Hokkaido from Honshu, although the two islands are connected by the underwater railway Seikan Tunnel...
, and even the regions of Chugoku and Shikoku
Shikoku
is the smallest and least populous of the four main islands of Japan, located south of Honshū and east of the island of Kyūshū. Its ancient names include Iyo-no-futana-shima , Iyo-shima , and Futana-shima...
in western Japan at more than 500 kilometer from the Fukushima-plant. Rain did accumulate the Cesium into the soil. Measured radiation densites per kilogram reached 250 becquerels in eastern Hokkaido, and 25 becquerels in the mountains of western Japan. According to the research-group, these levels decontamination were not high enough to require decontamination. Professor Tetsuzo Yasunari of the University of Nagoya called for a national soil-testing program because of the nationwide spread of radioactive material, and suggested identified hotspots, places with high radiation levels, should be marked with warning signs.
The first study concentrated on Cesium-137. Around the nuclear plant places were found containing up to 40.000 Becquerel/kg, 8 times the governmental safety-limit of 5.000 Becquerel/kg. Places further away are just below this maximum. East and north-east from the plant the soil was contaminated most. North-west and westwards the soil was less contaminated, because of mountain protection.
The second study had a wider scope, and was meant to study the geographic spread of more radioactive isotopes, like tellurium and iodine. Because these isotopes deposit itself into the soil with rain, Norikazu Kinoshita and his colleagues looked after the effect of two specific rain-showers at 15 March and 21 March 2011. The rainfall at 15 March contaminated the grounds around the plant, the second shower transported the radiation far further from the plant, in the direction of Tokyo. According to the authors, the soil should be decontaminated, but when this is found impossible, farming should be limited.
Radiation exposure in the city of Fukushima
All citizens of the town Fukushima did receive dosimeters to measure the precise dose of radiation they endure. After the month September the city of Fukushima did collect the 36.478 "glass badges" of dosimeters from all its citizens for analysis. It turned out, that 99 percent had not been exposed to more than 0.3 millisieverts in September 2011. Except four young children from one family, a girl, in third year elementary school, had received 1.7 millisieverts, her three brothers had been exposed to 1.4 to 1.6 millisieverts. Their home was situated near a highly-radioactive spot, and after this find the family did move out of the prefecture Fukushima. A city official said, that this kind of exposure would not affect their health.Disposal of radioactive ashes of waste facilities
Due to objections of concerned residents it became more and more difficult to dispose of the ashes of burned household garbage in and around Tokyo. The ashes of waste facilities in the TohokuTohoku region
The is a geographical area of Japan. The region occupies the northeastern portion of Honshu, the largest island of Japan. The region consists of six prefectures : Akita, Aomori, Fukushima, Iwate, Miyagi and Yamagata....
, Kanto
Kanto region
The is a geographical area of Honshu, the largest island of Japan. The region includes the Greater Tokyo Area and encompasses seven prefectures: Gunma, Tochigi, Ibaraki, Saitama, Tokyo, Chiba, and Kanagawa. Within its boundaries, slightly more than 40 percent of the land area is the Kantō Plain....
and Kōshin'etsu regions were proven to be contaminated with radioactive caesium. According to the guidelines of the Ministry of Environment
Ministry of the Environment (Japan)
The ' of Japan was formed in 2001 from the sub-cabinet level Environmental Agency established in 1971. The minister is a member of the Cabinet and is chosen by the Prime Minister, usually from the Diet., the current is Goshi Hosono...
, ashes with 8,000 becquerels per kilogram or lower, could be buried. Ashes with caesium levels between 8,000 and 100,000 becquerels should be secured, and buried in concrete vessels. A survey was done on 410 sites of waste disposal facilities, on how the ash disposal is proceeding. At 22 sites, mainly in the Tokyo Metropolitan area, the ashes with levels under 8000 becquerels could not be buried due to the objections of concerned residents. On 42 sites ashes were found that contained over 8,000 becquerels of caesium, that could not be buried. The ministry made plans to send officials to meetings in the municipalities to explain to the Japanese people that the waste disposal was done safely, and to demonstrate how the disposal of the ashes above 8000 bequerels was conducted.
Deposition of radioactivity and effect on agricultural products
Radiation monitoring in all 47 prefecturesPrefectures of Japan
The prefectures of Japan are the country's 47 subnational jurisdictions: one "metropolis" , Tokyo; one "circuit" , Hokkaidō; two urban prefectures , Osaka and Kyoto; and 43 other prefectures . In Japanese, they are commonly referred to as...
showed strong variation, but an upward trend in 10 of them on 23 March. No deposition could be determined in 28 of them until 25 March The highest value obtained was in Ibaraki (480 Bq/m2 on 25 March) and Yamagata (750 Bq/m2 on 26 March) for iodine-13. For caesium-137, the highest value were in Yamagata at 150 and 1200 Bq/m2 respectively.
Measurements made by Japan in a number of locations have shown the presence of radionuclide
Radionuclide
A radionuclide is an atom with an unstable nucleus, which is a nucleus characterized by excess energy available to be imparted either to a newly created radiation particle within the nucleus or to an atomic electron. The radionuclide, in this process, undergoes radioactive decay, and emits gamma...
s in the ground. On 19 March, upland soil levels of 8,100 Bq/kg of Cs-137 and 300,000 Bq/kg of I-131 were reported. One day later, the measured levels were 163,000 Bq/kg of Cs-137 and 1,170,000 Bq/kg of I-131.
Summary of restrictions imposed by the Japanese government as of 25 April 2011
| Item | Shipping restrictions | Consumption restrictions | ||||
|---|---|---|---|---|---|---|
| Fukushima | Ibaraki | Tochigi | Gunma | Chiba | Fukushima | |
| Raw milk | 3/21 – 4/8: Kitakata, Bandai, Inawashiro, Mishima, Aizumisato, Shimogou, Minami-aizu 3/21 – 4/16: Fukushima, Nihonmatsu, Date, Motomiya, Kunimi, Ootama, Kooriyama, Sukagawa, Tamura (excl. former Miyakoji), Miharu, Ono, Kagamiishi, Ishikawa, Asakawa, Hirata, Furudono, Shirakawa, Yabuki, Izumizaki, Nakajima, Nishigou, Samegawa, Hanawa, Yamatsuri, Iwaki 3/21 – 4/21: Souma, Shinchi 3/21 – ongoing: All other areas |
3/23 – 4/10: All areas | ||||
| Spinach | 3/21 – ongoing: All areas | 3/21 – 4/17: All areas except Kita-ibaraki, Takahagi 3/21 – ongoing: Kita-ibaraki, Takahagi |
3/21 – 4/21: Nasushiobara, Shioya 3/21 – ongoing: All other areas |
3/21 – 4/8: All areas | 4/4 – 4/22: Asahi, Katori, Tako | 3/23 – ongoing: All areas |
| Kakina | 3/21 – ongoing: All areas | 3/21 – 4/17: All areas | 3/21 – 4/14: All areas | 3/21 – 4/8: All areas | 3/23 – ongoing: All areas | |
| Chrysanthemum | 3/23 – ongoing: All areas | 4/4 – 4/22: Asahi | 3/23 – ongoing: All areas | |||
| Bok choi | 3/23 – ongoing: All areas | 4/4 – 4/22: Asahi | 3/23 – ongoing: All areas | |||
| Korean lettuce | 3/23 – ongoing: All areas | 4/4 – 4/22: Asahi | 3/23 – ongoing: All areas | |||
| Other non-round leafy vegetables | 3/23 – ongoing: All areas | 3/23 – ongoing: All areas | ||||
| Round leafy vegetables (such as cabbage) | 3/23 – ongoing: All areas | 3/23 – ongoing: All areas | ||||
| Brassicaceae Brassicaceae Brassicaceae, a medium sized and economically important family of flowering plants , are informally known as the mustards, mustard flowers, the crucifers or the cabbage family.... buds (broccoli, cauliflower, etc.) |
3/23 – ongoing: All areas | 3/23 – ongoing: All areas | ||||
| Turnip | 3/23 – ongoing: All areas | |||||
| Parsley | 3/23 – 4/17: All areas | 4/4 – 4/22: Asahi | ||||
| Celery | 4/4 – 4/22: Asahi | |||||
| Shiitake | 4/13 – 4/25: Iwaki 4/13 – ongoing: Shinchi, Date, Iitate, Souma, Minami-souma, Namie, Futaba, Ookuma, Tomioka, Naraha, Hirono, Kawamata, Katsurao, Tamura, Kawauchi 4/18 – ongoing: Fukushima 4/25 – ongoing: Motomiya |
4/13 – ongoing: Iitate | ||||
| Sand lance Sand lance A sand lance or sandlance is a fish belonging to the family Ammodytidae. Several species of sand lance are commonly known as "sand eels" or "sandeels", though they are not related to true eels. Another variant name is launce, and all names of the fish are references to its slender body and... young |
4/20 – ongoing: All areas | 4/20 – ongoing: All areas | ||||
Agricultural products
On 19 March, the Japanese Ministry of Health, Labour and Welfare announced that levels of radioactivity exceeding legal limits had been detected in milk produced in the Fukushima area and in certain vegetables in Ibaraki. On 21 March, IAEA indicated it confirmed that "in some areas, iodine-131 in milk and in freshly grown leafy vegetables, such as spinach and spring onions, is significantly above the levels set by Japan for restricting consumption". One day later, iodine-131 (sometimes above safe levels) and caesium-137 (always at safe levels) detection was reported in Ibaraki prefecture. On 21 March, levels of radioactivity in spinach grown in open air in Kitaibaraki city in IbarakiIbaraki
Ibaraki may refer to any of the following places in Japan:* Ibaraki Prefecture, one of the 47 prefectures of Japan**Ibaraki, Ibaraki, a town in Ibaraki Prefecture* Ibaraki, Osaka, a city in Osaka PrefectureIt can also refer to:...
, around 75 kilometers south of the nuclear plant, were 24,000 becquerel (Bq)/kg of iodine-131, 12 times more than the limit of 2,000 Bq/kg, and 690 Bq/kg of caesium, 190 Bq/kg above the limit. In four Prefectures (Ibaraki, Totigi, Gunma, Fukushima) distributing of spinach and kakina was restricted as well as milk from Fukushima. On 23 March, similar restrictions were placed on more leafy vegetables (komatsuna
Komatsuna
Komatsuna is a type of leaf vegetable. It is a variant of the same species as the common turnip. It is grown commercially in Japan, Taiwan and Korea; the name is from Japanese . It is also known as Japanese Mustard Spinach and is usually stir-fried, pickled, boiled and added to soups or used fresh...
, cabbages) and all flowerhead brassica
Brassica
Brassica is a genus of plants in the mustard family . The members of the genus may be collectively known either as cabbages, or as mustards...
s (like cauliflower) in Fukushima, while parsley
Parsley
Parsley is a species of Petroselinum in the family Apiaceae, native to the central Mediterranean region , naturalized elsewhere in Europe, and widely cultivated as an herb, a spice and a vegetable.- Description :Garden parsley is a bright green hairless biennial herbaceous plant in temperate...
and milk distribution was restricted in Ibaraki. On 24 March, IAEA reported that virtually all milk samples and vegetable samples taken in Fukushima and Ibaraki on 18–21 and 16–22 March respectively were above the limit. Samples from Chiba, Ibaraki and Tochigi also had too high levels in celery
Celery
Apium graveolens is a plant species in the family Apiaceae commonly known as celery or celeriac , depending on whether the petioles or roots are eaten: celery refers to the former and celeriac to the latter. Apium graveolens grows to 1 m tall...
, parsley, spinach and other leafy vegetables. In addition, certain samples of beef mainly taken on 27–29 March showed concentrations of iodine-131 and/or caesium-134 and caesium-137 above the regulatory levels.
After the detection of radioactive caesium
Caesium
Caesium or cesium is the chemical element with the symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a melting point of 28 °C , which makes it one of only five elemental metals that are liquid at room temperature...
above legal limits in Sand lance
Sand lance
A sand lance or sandlance is a fish belonging to the family Ammodytidae. Several species of sand lance are commonly known as "sand eels" or "sandeels", though they are not related to true eels. Another variant name is launce, and all names of the fish are references to its slender body and...
s caught off the coast of Ibaraki Prefecture
Ibaraki Prefecture
is a prefecture of Japan, located in the Kantō region on the main island of Honshu. The capital is Mito.-History:Ibaraki Prefecture was previously known as Hitachi Province...
, the government of the prefecture banned such fishing. On 11 May, caesium levels in tea leaves from a prefecture "just south of Tokyo" were reported to exceed government limits, this was the first agricultural product from Kanagawa Prefecture that exceeded safety limits. In addition to Kanagawa Prefecture, agricultural products from Tochigi and Ibaraki prefectures have also been found to exceed the government limits, for example, pasture grass collected on 5 May, measured 3,480 Bq/kg of radioactive caesium, approximately 11 times the state limit of 300 becquerels. Even into July radioactive beef
Beef
Beef is the culinary name for meat from bovines, especially domestic cattle. Beef can be harvested from cows, bulls, heifers or steers. It is one of the principal meats used in the cuisine of the Middle East , Australia, Argentina, Brazil, Europe and the United States, and is also important in...
was found on sale in eleven prefectures, as far away as Kochi
Kochi Prefecture
is a prefecture of Japan located on the south coast of Shikoku. The capital is the city of Kōchi.- History :Prior to the Meiji Restoration, Kōchi was known as Tosa Province and was controlled by the Chosokabe clan in the Sengoku period and the Yamauchi family during the Edo period.- Geography...
and Hokkaido
Hokkaido
, formerly known as Ezo, Yezo, Yeso, or Yesso, is Japan's second largest island; it is also the largest and northernmost of Japan's 47 prefectural-level subdivisions. The Tsugaru Strait separates Hokkaido from Honshu, although the two islands are connected by the underwater railway Seikan Tunnel...
. Authorities explained that until that point testing had only been performed on the skin and exterior of livestock, animal feed and meat cuts had not been checked for radiation previously.
Hay and straw were found contaminated with caesium, 80 kilometers from the reactors, far outside the evacuation-zone. The news of the contamination of foods with radioactive substances leaking from the Fukushima nuclear reactors damaged the mutual trust between local food producers including farmers and consumers. Everywhere in Japan banners and stickers were found with: "Hang in there, Fukushima!", numerous harmful rumors on Fukushima products could be found online. Many rumors that were discriminatory to Fukushima and other messages slandering Fukushima people could be found on the Internet. The source of cesium was found to be rice straw that had been fead to the animal. But a notice of the Japanese government, that was sent to cattle-farmers after the nuclear accident made no mention to the possibility that rice straw could be contaminated with radioactive materials from the plant. Beef from the prefecture Fukushima was taken from the distribution-channels. But health minister Kohei Otsuka, mentioned on 17 July 2011 that this could be not enough. An inspection was set up, testing the urine of all cows, to be able to return those cows that showed levels of radioactive substances higher than the government-set limit to farms so they could be decontaminated feeding safe hay. According to the minister, the Japanese government should try to buy not-contaminated straw and hay in other parts of the country and offering this to the farmers in the affected areas. All transports of beef raised in the prefecture Fukushima was prohibited after 19 July. The meat of some 132 cows was sold to at least 36 of the 47 prefectures of Japan. In more and more places contaminated meat was found.
Cattle and beef
As of July 2011, the Japanese government has been unable to control the spread of radioactive material into the nation’s food, and "Japanese agricultural officials say meat from more than 500 cattle that were likely to have been contaminated with radioactive caesium has made its way to supermarkets and restaurants across Japan". On 22 July it became known, that at least 1400 cows were shipped from 76 farms that were fed with contaminated hay and rice-straw, that had been distributed by agents in Miyagi and farmers in the prefectures of Fukushima and Iwate, near the crippled Fukushima Daiichi nuclear power plant. Supermarkets and other stores were asking their customers to return the meat. Farmers were asking for help, and the Japanese government was considering whether it should buy and burn all this suspect meat.On 26 July the body-count was more than 2,800 cows fed with caesium-contaminated food, shipped to 46 of the 47 prefectures in Japan, only Okinawa remained free. Part of this beef, that had reached the markets, still needed to be tested. In an attempt to ease consumer-concern the Japanese government promised to impose inspections on all this beef, and to buy the meat back when higher-than-permissible caesium levels were detected during the tests. The government planned to eventually pass on the buy-back costs to TEPCO. The same day the Japanese ministry of agriculture urged farmers and merchants to renounce the use and sale of compost made of manure from cows that may have been fed the contaminated straw. The measure also applied to humus from leaves fallen from trees. After developing guidelines for safety levels of radioactive caesium in compost and humus, this voluntary ban could be lifted.
On 28 July a ban was imposed on all the shipments on cattle from the prefecture Miyagi
Miyagi
-Places:* Miyagi Prefecture, one of the 47 major divisions of Japan* Miyagi, Gunma, a village in Japan, merged into Maebashi in 2004-People:* Michio Miyagi , Japanese koto musician* Chōjun Miyagi , Japanese martial artist...
. Some 1,031 beasts had been shipped that probably were fed with contaminated rice-straw. After measurements in 6 of them revealed 1,150 becquerels per kilogram, more than twice the governmental set safety level. Because the origins were scattered all over the prefecture, Miyagi became the second prefecture with a ban on all beef cattle shipments. In the year before 11 March about 33,000 cattle were traded from Miyagi.
On 1 August a ban was put on all cattle in the prefecture Iwate
Iwate
Iwate can refer to:* Iwate Prefecture, a prefecture of Japan.* Iwate, Iwate, a town in Iwate Prefecture, Japan.* Japanese cruiser Iwate, an armored cruiser of the Imperial Japanese Navy from 1900 to the end of World War II....
, after 6 cows from two villages were found with heavy levels of caesium. Iwate was the third prefecture where this was decided. Shipments of cattle and meat would only be allowed after examination, and when the level of caesium was below the regulatory standard. In Iwate some 36,000 cattle was produced in a year. All cattle would be checked for radiation exposure before shipment, and the Japanese government asked the prefecture to temporarily reduce the number of shipments to match its inspection capability.
On 3 August, yet another local government in western Japan, the prefecture Shimane, decided to conduct radiation checks on all beef cattle to ease consumer concerns about food safety. Starting from the second week of August all cattle would be tested. Late July at one farm in this prefecture rice-straw was discovered with radioactive caesium levels exceeding the government safety guide. Although all other tests of beef cattle found far lower levels of radioactivity than the government standard, prices of beef from Shimane plummeted and wholesalers avoided all cattle from the prefecture. All processed beef would undergo preliminary screening, and meat registering 250 becquerels per kilogram or more of radioactive caesium – half the government safety level – would be tested further.
The second week of August the prefecture of Fukushima
Fukushima
may refer to:*Fukushima City – the capital city of Fukushima Prefecture, Japan*Fukushima Prefecture – a Japanese prefecture*Two nuclear power plants located in Fukushima Prefecture:**Fukushima Daiichi Nuclear Power Plant...
started with a buy-out of all cattle that could not be sold because the high levels of caesium in the meat. The prefecture decided to buy back all beef cattle that had become too old for shipment due to the shipping suspension in place since July.
On 2 August a group of farmers agreed with the Fukushima prefectural government to set up a consultative body as early as next week to regulate this process. The prefectural government would provide the subsidies needed. There was some delay, because the farmers and the local government could not agree about the prices for the cattle, further negotiations were needed. The problems for the farmers were growing, because they did not know how to protect their cattle from contamination and did not how to feed their cattle. A senior official of the farmers said that the buy-up plan needed to be implemented without any delay.
In response to calls for more support by farmers the Japanese government unfolded on the 5 August 2011 a plan to buy up all beef contaminated with radioactive caesium, that had already reached the distribution chains, as an additional measurement to support beef cattle farmers.
The plan included:
- the buy-out of about 3,500 head of cattle suspected to have been fed with contaminated rice straw, with caesium in excess of the safety limit.
- regardless the fact that some beef could be within the national safety limits.
- all this meat would be burned, to keep it out of distribution-channels
Other measurements were the expansion of subsidies to beef cattle farmers:
- Farmers who were unable to ship their cattle due to restrictions received 50,000 yen, (~ 630 dollars) per head of cattle regardless of the cattle's age.
- financial support was offered to prefectures that were buying up beef cattle, that had become too old to ship due to the ban.
- The Japanese Government planned to go on to buy all beef containing unsafe levels of radioactive caesium that reached the market through private organizations.
On 19 August 2011 was reported, the meat of 4 cows from one Fukushima farm had been found to be contaminated with radioactive caesium in excess of the government-set safety limits. The day after the meat of 5 other cows from this farm was also found to contain radioactive caesium. Because of this the central government on Friday to put off lifting a shipment ban on Fukushima beef. The 9 cows were among a total of over 200 head of cattle shipped from the farm and slaughtered at a facility in Yokohama city between the 11 March nuclear accident and April. The meat of the 9 had been stored by a food producer. The farmer denied feeding the cows contaminated rice straw, in stead he used imported hay that had been stored at another farm.
Natto
On 13 August 2011, a group of 5 manufacturers of natto, or fermented soybeans, in Mito city, Ibaraki Prefecture, planned to seek damages from TEPCO because their sales had fallen to almost 50 percent of normal. Natto is normally packed in rice-straw and after the discovery of the caesium contamination of the straw, they had lost a lot of their normal customers. The lost sales from April until August 2011 had risen to around 1.3 million dollars.Tea-leaves
On 3 September 2011 radioactive caesium exceeding the government's safety limit had been detected in tea leaves in Chiba and Saitama prefectures, near Tokyo. This was the ministry's first discovery of radioactive substances beyond legal limits since the tests of food stuffs started in August. These tests were conducted in order to verify local government data using different numbers and kinds of food samples. Tea leaves of one type of tea from Chiba Prefecture contained 2,720 becquerels of radioactive caesium per kilogram, 5 times above the legal safety limit. A maximum of 1,530 becquerels per kilogram was detected in 3 kinds of tea leaves from Saitama Prefecture. Investigations were done to find out where the tea was grown, and to determine how much tea had already made its way to market. Tea producers were asked to recall their products, when necessary.Rice
On 19 August radioactive caesium was found in a sample of rice. This was in Ibaraki Prefecture, just north of Tokyo, in a sample of rice from the city of Hokota, about 100 miles south of the radiation-spewing nuclear plant. The prefecture said the radiation was well within safe levels: it measured 52 becquerels per kilogram, about one-tenth of the government-set limit for grains. Two other samples tested at the same time showed no contamination. The Agriculture Ministry said it was the first time that more than trace levels of cesium had been found in rice.On 16 September 2011 the results were published of the measurements of radioactive cesium in rice. The results were known of around 60 percent of all test-locations. Radioactive materials were detected in 94 locations, or 4.3 percent of the total. But the highest level detected so far, in Fukushima prefecture, was 136 becquerels per kilogram, about a quarter of the government's safety limit of 500 Becquerel per kilogram. Tests were conducted in 17 prefectures, and were completed in more than half of them. In 22 locations radioactive materials were detected in harvested rice. The highest level measured was 101.6 becquerels per kilogram, or one fifth of the safety limit. Shipments of rice did start in 15 prefectures, including all 52 municipalities in the prefecture Chiba
Chiba
-Places:* Chiba, Chiba, capital city of Chiba Prefecture, Japan* Chiba Prefecture, a sub-national jurisdiction in the Greater Tokyo Area on the eastern coast of Honshū Island, Japan* Chiba Station, a train station in Chiba, Chiba...
. In Fukushima shipments of ordinary rice did start in 2 municipalities, and those of early-harvested rice in 20 municipalities.
On 23 September 2011 radioactive caesium in concentrations above the governmental safety limit was found in rice samples collected in an area in the northeastern part of the prefecture Fukushima. Rice-samples taken before the harvest showed 500 becquerels per kilogram in the city of Nihonmatsu. The Japanese government ordered a two way testing procedure of samples taken before and after the harvest. Pre-harvest tests were carried out in nine prefectures in the regions of Tohoku and Kanto. After the find of this high level of cesium, the prefectural government dis increase the number of places to be tested within the city from 38 to about 300. The city of Nihonmatsu held an emergency meeting on 24 September with officials from the prefecture government. The farmers, that already had started harvesting, were ordered to store their crop until the post-harvest tests were available.
On 16 November 630 becquerels per kilogram of radioactive cesium was detected in rice harvested in the Oonami district in Fukushima City.
All rice of the fields nearby was stored and none of this rice had been sold to the market. On 18 November all 154 farmers in the district were asked to suspend all shipments of rice. Tests were ordered on rice samples from all 154 farms in the district. The result of this testing was reported on 25 November: five more farms were found with cesium contaminated rice at a distance of 56 kilometers from the disaster reactors in the Oonami district of Fukushima City, The highest level of cesium detected was 1,270 becquerels per kilogram.
On 28 November 2011 the prefecture of Fukushima reported the find of cesium-contaminated rice, up to 1050 Becquerels per kilogram, in samples of 3 farms in the city Date
Date, Fukushima
is a city located in northern Fukushima, Japan.As of May 2011, the town has an estimated population of 65,409 and the total area is 265 km².There were nine towns in Date District, Fukushima. On January 1, 2006, five towns in Date District merged to form the city of Date. Merged towns were Hobara,...
at a distance of 50 kilometers from the Fukushima Daiichi reactors. Some 9 kilo's of this crops were already sold locally before this date. Officials tried to find out who bought this rice. Because of this and earlier finds the government of the prefecture Fukushima decided to control more than 2300 farms in the whole district on cesium-contamination. A more precise number was mentioned by the Japanese newspaper The Mainichi Daily News: on 29 November orders were given to 2381 farms in Nihonmatsu and Motomiya to suspend part of their rice shipments. This number added to the already halted shipments at 1941 farms in 4 other districts including Date
Date District, Fukushima
is a district located in Fukushima, Japan.As of 2008, the district has an estimated population of 39,633 and a density of 190 persons per km². The total area is 208.53 km².-Towns and villages:*Kawamata*Kōri*Kunimi-Mergers:...
, raised the total to 4322 farms.
Mushrooms
On 13 October 2011 the city of YokohamaYokohama
is the capital city of Kanagawa Prefecture and the second largest city in Japan by population after Tokyo and most populous municipality of Japan. It lies on Tokyo Bay, south of Tokyo, in the Kantō region of the main island of Honshu...
terminated the use of dried shiitake-mushrooms in school lunches after tests had found radioactive cesium in them up to 350 bcquerels per kilogram. In shiitake mushrooms grown outdoors on wood in a city in the prefecture Ibaraki
Ibaraki
Ibaraki may refer to any of the following places in Japan:* Ibaraki Prefecture, one of the 47 prefectures of Japan**Ibaraki, Ibaraki, a town in Ibaraki Prefecture* Ibaraki, Osaka, a city in Osaka PrefectureIt can also refer to:...
, 170 kilometers from the nuclear plant, samples contained 830 becquerels per kilogram of radioactive cesium, exceeding the government's limit of 500 becquerels. Radioactive contaminated shiitake mushrooms, above 500 becquerels per kilogram, were also found in two cities of prefecture Chiba
Chiba
-Places:* Chiba, Chiba, capital city of Chiba Prefecture, Japan* Chiba Prefecture, a sub-national jurisdiction in the Greater Tokyo Area on the eastern coast of Honshū Island, Japan* Chiba Station, a train station in Chiba, Chiba...
, therefore restrictions were imposed on the shipments from these cities.
On 29 October the government of the prefecture Fukushima
Fukushima
may refer to:*Fukushima City – the capital city of Fukushima Prefecture, Japan*Fukushima Prefecture – a Japanese prefecture*Two nuclear power plants located in Fukushima Prefecture:**Fukushima Daiichi Nuclear Power Plant...
announced that shiitake mushrooms grown indoors at a farm in Soma
Soma
Soma , or Haoma , from Proto-Indo-Iranian *sauma-, was a ritual drink of importance among the early Indo-Iranians, and the subsequent Vedic and greater Persian cultures. It is frequently mentioned in the Rigveda, whose Soma Mandala contains 114 hymns, many praising its energizing qualities...
situated at the coast north from the Fukushima Daiichi plant were to be contaminated with radioactive cesium: They contained 850 becquerels per kilogram, and exceeded the national safety-limit of 500-becquerel. The mushrooms were grown on beds made of woodchips mixed with other nutrients. The woodchips in the mushroom-beds sold by the agricultural cooperative of Soma were thought to have caused of the contamination. Since 24 October 2011 this farm had shipped 1,070 100-gram packages of shiitake mushrooms to nine supermarkets. Besides these no other shiitake mushrooms produced by the farm were sold to customers.
In the city of Yokohama
Yokohama
is the capital city of Kanagawa Prefecture and the second largest city in Japan by population after Tokyo and most populous municipality of Japan. It lies on Tokyo Bay, south of Tokyo, in the Kantō region of the main island of Honshu...
in March and October food was served to 800 people with dried shiitake
Shiitake
The Shiitake is an edible mushroom native to East Asia, which is cultivated and consumed in many Asian countries, as well as being dried and exported to many countries around the world. It is a feature of many Asian cuisines including Vietnamese, Chinese, Japanese, Korean and Thai...
-mushrooms that came from a farm near this town at a distance of 250 kilometer from Fukushima. The test-results of these mushrooms showed 2,770 Becquerels per kilo in March and 955 Becquerels per kilo in October, far above the limit of 500 Becquerels per kilo set by the Japanese government. The mushrooms were checked for contamination in the first week of November, after requests of concerned people with questions about possible contamination of the food served. No mushrooms were sold elsewhere.
On 10 November 2011 some 120 kilometers away southwest from the Fukushima-reactors in the prefecture Tochigi
Tochigi
Tochigi can refer to:* Tochigi Prefecture, a Japanese prefecture* Tochigi, Tochigi, a city in Tochigi prefecture, Japan* Tochigi Station, a railroad station in Tochigi city, Japan.* Tochigi S.C., a Japanese soccer club...
649 becquerels of radioactive cesium per kilogram was measured in kuritake mushrooms. Four other cities of Tochigi did already stop with the sales and shipments of the mushrooms grown there. The farmers were asked to stop all shipments and to call back the mushrooms already on the market.
Drinking water
The regulatory safe level for iodine-131 and caesium-137 in drinking water in Japan are 100 Bq/kg and 200 Bq/kg respectively. The Japanese science ministry said on 20 March that radioactive substances were detected in tap waterTap water
Tap water is a principal component of "indoor plumbing", which became available in urban areas of the developed world during the last quarter of the 19th century, and common during the mid-20th century...
in Tokyo, as well as Tochigi
Tochigi
Tochigi can refer to:* Tochigi Prefecture, a Japanese prefecture* Tochigi, Tochigi, a city in Tochigi prefecture, Japan* Tochigi Station, a railroad station in Tochigi city, Japan.* Tochigi S.C., a Japanese soccer club...
, Gunma, Chiba
Chiba
-Places:* Chiba, Chiba, capital city of Chiba Prefecture, Japan* Chiba Prefecture, a sub-national jurisdiction in the Greater Tokyo Area on the eastern coast of Honshū Island, Japan* Chiba Station, a train station in Chiba, Chiba...
and Saitama
Saitama Prefecture
is a prefecture of Japan located in the Kantō region of the island of Honshu. The capital is the city of Saitama.This prefecture is part of the Greater Tokyo Area, and most of Saitama's cities can be described as suburbs of Tokyo, to which a large amount of residents commute each day.- History...
prefectures. IAEA reported on 24 March that drinking water in Tokyo, Fukushima and Ibaraki had been above regulatory limits between 16 and 21 March. On 26 March, IAEA reported that the values were now within legal limits. On 23 March, Tokyo drinking water exceeded the safe level for infants, prompting the government to distribute bottled water to families with infants. Measured levels were caused by iodine-131
Iodine-131
Iodine-131 , also called radioiodine , is an important radioisotope of iodine. It has a radioactive decay half-life of about eight days. Its uses are mostly medical and pharmaceutical...
(I-131) and were 103, 137 and 174 Bq/l. On 24 March, iodine-131 was detected in 12 of 47 prefectures, of which the level in Tochigi was the highest at 110 Bq/kg. Caesium-137 was detected in 6 prefectures but always below 10 Bq/kg. On 25 March, tap water was reported to have reduced to 79 Bq/kg and to be safe for infants in Tokyo and Chiba but still exceeded limits in Hitachi and Tokaimura. On 27 April, "radiation in Tokyo’s water supply fell to undetectable levels for the first time since 18 March."
The following graphs show Iodine-131 water contaminations measured in water purifying plants From 16 March to 7 April:
On 2 July samples of tapwater taken in Tokyo Shinjuku ward radioactive caesium-137 was detected for the first time since April. The concentration was 0.14 becquerel per kilogram and none was discovered yesterday, which compares with 0.21 becquerel on 22 April, according to the Tokyo Metropolitan Institute of Public Health. No caesium-134 or iodine-131 was detected. The level was below the safety limit set by the government. "This is unlikely to be the result of new radioactive materials being introduced, because no other elements were detected, especially the more sensitive iodine," into the water supply, were the comments of Hironobu Unesaki, a nuclear engineering professor at Kyoto University.
Breast milk
Small amounts of radioactive iodineIodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
were found in the breast milk
Breast milk
Breast milk, more specifically human milk, is the milk produced by the breasts of a human female for her infant offspring...
of women living east of Tokyo
Tokyo
, ; officially , is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area of Japan. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family...
. However, the levels were below the safety limits for tap water consumption by infants.
Children
In a survey by the local and central governments conducted on 1,080 children aged 0 to 15 in Iwaki, Kawamata and Iitate on 26–30 March, almost 45 percent of these children had experienced thyroidThyroid
The thyroid gland or simply, the thyroid , in vertebrate anatomy, is one of the largest endocrine glands. The thyroid gland is found in the neck, below the thyroid cartilage...
exposure to radiation with radioactive iodine
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
, although in all cases the amounts of radiation did not warrant further examination, according to the Nuclear Safety Commission
Nuclear Safety Commission
Nuclear Safety Commissions are governmental nuclear power and materials watchdogs and may refer to:* Canadian Nuclear Safety Commission* Japanese Nuclear Safety Commission...
on Tuesday 5 July. In October 2011, hormonal
Hormone
A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...
irregularies in 10 evacuated children were reported. However, the organization responsible for the study said that no link had been established between the children's condition and explosure to radiation.
On 9 October a survey started in the prefecture Fukushima: ultrasonic examinations were done of the thyroid glands of all 360.000 children between 0 to 18 years of age. Follow-up tests will be done for the rest of their lives. This was done in response to concerned parents, alarmed by the evidence showing increased incidence of thyroid cancer among children after the 1986 Chernobyl disaster. The project was done by the Medical University of Fukushima. The results of the tests will be mailed to the children within a month. At the end of 2014 the initial testing of all children should be completed, after this the children will undergo a thyroid checkup every 2 years until they turn 20, and once every 5 years above that age.
In November 2011 in urine-samples of 1500 pre-school-children (ages 6 years or younger) from the city of Minamisoma in the prefecture Fukushima radioactive cesium was found in 104 cases. Most had levels between 20 and 30 becquerels per liter, just above the detection limit, but 187 becquerels was found in the urine of a one-year-old baby boy. All was done because the parents were afraid for internal exposure. Local governments only covered the tests for elementary schoolchildren and older students. According to RHC JAPAN a medical consultancy firm in Tokyo, these levels could not harm the health of the children. But director Makoto Akashi of the National Institute of Radiological Sciences said, that although those test results should be verified, this still proved the possibility of internal exposure in the children of Fukushima, but that the internal exposure would not increase, when all food was tested for radioactivity before consumption.
Soil
Also in July citizens groups reported that a survey of soil at four places in the city of Fukushima taken on 26 June proved that all samples were contaminated with radioactive caesium, measuring 16,000 to 46,000 becquerels per kilogram and exceeding the legal limit of 10,000 becquerels per kg, A study published by the PNAS found that cesium 137 had 'strongly contaminated the soils in large areas of eastern and northeastern Japan'http://www.pnas.org/content/early/2011/11/11/1112058108Wild-life
After the find of 28,000 becquerels of caesium per kilogram in wild mushrooms and a wild boar was found with radiation amounts about 6 times the safety limit, Professor Yasuyuki Muramatsu at the Gakushuin UniversityGakushuin University
is an elite higher educational institution in Mejiro, Toshima Ward, Tokyo. It was re-established after World War II as an affiliate of the Gakushūin School Corporation, the privatized successor to the original Gakushūin University or "Peers School" set up during the Meiji era to educate the...
urged detailed checks on wild plants and animals. Radioactive caesium in soil and fallen leaves in forests in his opinion would be easily absorbed by mushrooms and edible plants. He said that wild animals like boars were bound to accumulate high levels of radiation by eating contaminated mushrooms and plants. The professor added that detailed studies were needed on wild plants and animals. Across Europe the Chernobyl-incident had likewise effects on wild fauna and flora.
Plankton
Radioactive cesium was found in high concentration in plankton in the sea near the Fukushima Daiichi Nuclear Power Plant. Samples were taken up to 60 kilometers from the coast of IwakiIwaki
-Places:*Iwaki, Fukushima: a city in Japan.*Iwaki, Akita: a town in Japan.*Iwaki Province: an old province of Japan.*Iwaki : a volcano on the Japanese island of Honshū....
city in Juli 2011 by scientists of the Tokyo University of Marine Science and Technology. Up to 669 becquerels per kilogram of radioactive cesium was measured in samples of animal plankton taken 3 kilometers offshore. The leader of the research-group Professor Takashi Ishimaru, said that the sea current continuously carried contaminated water southwards from the plant. Further studies to determine the effect on the food-chain and fish would be needed.
Radiation-limits
Vladimir Babenko, a Belarusian scientist and deputy director of the Belrad Institute of Radiation Safety in the former Soviet republic, said at a press-conference on 12 October 2011 that he thinks, that the Japanese radiation food limits were set too high, and that the limits in his own country were much lower. He also criticized the Japanese government for its failure to set special standards for children to better protect them from internal radiation exposure. The Japanese limit for radioactive cesium in drinking water is 200 becuerels per liter, 20 times higher than the limit in BelarusBelarus
Belarus , officially the Republic of Belarus, is a landlocked country in Eastern Europe, bordered clockwise by Russia to the northeast, Ukraine to the south, Poland to the west, and Lithuania and Latvia to the northwest. Its capital is Minsk; other major cities include Brest, Grodno , Gomel ,...
: 10 becquerels per liter.
Decontamination efforts
In the last week of August premier minister Naoto Kan informed the governor of Fukushima Prefecture about the plans to build a central storage facility to store and treat nuclear waste including contaminated soil in Fukushima. On 27 August at a meeting in Fukushima City Governor Yuhei Sato spoke out his concern about the sudden proposals, and the implications that this would have for the prefecture and its inhabitants, that already had endured so much from the nuclear accident. Kan said, that the government had no intention to make the plant a final facility, but the request was needed in order to make a start with decontamination.Distribution by sea
Seawater containing measurable levels of iodine-131 and caesium-137 were collected by Japan Agency for Marine-Earth Science and Technology (JAMSTEC) on 22–23 March at several points 30 km from the coastline iodine concentrations were "at or above Japanese regulatory limits" while caesium was "well below those limits" according to an IAEA report on 24 March. On 25 March, IAEA indicated that in the long term, caesium-137 (with a half-life of 30 years) would be the most relevant isotope as far as doses was concerned and indicated the possibility "to follow this nuclide over long distances for several years." The organization also said it could take months or years for the isotope to reach "other shores of the Pacific".The survey by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) reveals that radioactive cesium released from Fukushima I Nuclear Power Plant reached the ocean 2000 kilometers from the plant and 5000 meters deep one month after the accident. It is considered that airborne cesium particles fell on the ocean surface, and sank as they were attached to the bodies of dead plankton. The survey result was announced in a symposium held on November 20 in Tokyo. From April 18 to 30, JAMSTEC collected "marine snow", sub-millimeter particles made mostly of dead plankton and sand, off the coast of Kamchatka Peninsula, 2000 kilometers away from Fukushima, and off the coast of Ogasawara Islands, 1000 kilometers away, at 5000 meters below the ocean surface. The Agency detected radioactive cesium in both locations, and from the ratio of cesium-137 and cesium-134 and other observations it was determined that it was from Fukushima I Nuclear Power Plant. The density of radioactive cesium is still being analyzed, according to the Agency. It has been thus confirmed that radioactive materials in the ocean are moving and spreading not just by ocean currents but by various other means.
Distribution by air
The United NationsUnited Nations
The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...
predicted that the initial radiation plume
Plume (hydrodynamics)
In hydrodynamics, a plume is a column of one fluid or gas moving through another. Several effects control the motion of the fluid, including momentum, diffusion, and buoyancy...
from the stricken Japanese reactors would reach the United States by 18 March. Health and nuclear experts emphasized that radioactive isotopes in the plume will be very diluted, and would have extremely minor health consequences in the United States. A simulation by the Belgian Institute for Space Aeronomy indicated that trace amounts of radioactivity would reach California and Mexico around 19 March. These predictions were tested by a worldwide network of highly sensitive radiative isotope measuring equipment, with the resulting data used to assess any potential impact to human health as well as the status of the reactors in Japan. Consequently, by 18 March radioactive fallout
Nuclear fallout
Fallout is the residual radioactive material propelled into the upper atmosphere following a nuclear blast, so called because it "falls out" of the sky after the explosion and shock wave have passed. It commonly refers to the radioactive dust and ash created when a nuclear weapon explodes...
including isotopes of iodine-131, iodine-132, tellurium-132, iodine-133, caesium-134 and caesium-137 was detected in air filters at the University of Washington, Seattle, USA.
Due to an anticyclone
Anticyclone
An anticyclone is a weather phenomenon defined by the United States' National Weather Service's glossary as "[a] large-scale circulation of winds around a central region of high atmospheric pressure, clockwise in the Northern Hemisphere, counterclockwise in the Southern Hemisphere"...
south of Japan, favorable westerly winds were dominant during most of the first week of the accident, depositing most of the radioactive material out to sea and away from population centers, with some unfavorable wind directions depositing radioactive material over Tokyo. Low-pressure area over Eastern Japan gave less favorable wind directions 21–22 March. Wind shift to north takes place Tuesday midnight. After the shift, the plume would again be pushed out to the sea for the next becoming days. Roughly similar prediction results are presented for the next 36 hours by the Finnish Meteorological Institute. In spite of winds blowing towards Tokyo during 21–22 March, he comments, "From what I've been able to gather from official reports of radioactivity releases from the Fukushima plant, Tokyo will not receive levels of radiation dangerous to human health in the coming days, should emissions continue at current levels."
Norwegian Institute for Air Research have continuous forecasts of the radioactive cloud and its movement. These are based on the FLEXPART model, originally designed for forecasting the spread of radioactivity from the Chernobyl disaster
Chernobyl disaster
The Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine , which was under the direct jurisdiction of the central authorities in Moscow...
.
As of 28 April, the Washington State Department of Health, one of the U.S. states nearest Japan, reported that levels of radioactive material from the Fukushima plant had dropped significantly, and were now often below levels that could be detected with standard tests.
Response in other countries
Rush for iodine
Fear of radiation from Japan prompted a global rush for iodine pills, including in the United States, Canada, Russia, Korea, China, Malaysia and Finland. There is a rush for iodized salt in China. A rush for iodine antiseptic solution appeared in Malaysia. WHOWho
Who may refer to:* Who , an English-language pronoun* who , a Unix command* Who?, one of the Five Ws in journalism- Art and entertainment :* Who? , a 1958 novel by Algis Budrys...
warned against consumption of iodine pills without consulting a doctor and also warned against drinking iodine antiseptic solution. The United States Pentagon said troops are receiving potassium iodide
Potassium iodide
Potassium iodide is an inorganic compound with the chemical formula KI. This white salt is the most commercially significant iodide compound, with approximately 37,000 tons produced in 1985. It is less hygroscopic than sodium iodide, making it easier to work with...
before missions to areas where possible radiation exposure is likely.
The World Health Organisation (WHO) says it has received reports of people being admitted to poison centres around the world after taking iodine tablets in response to fears about harmful levels of radiation coming out of the damaged nuclear power plant in Fukushima.
U.S. military
In Operation TomodachiOperation Tomodachi
is a United States Armed Forces assistance operation to support Japan in disaster relief following the 2011 Tōhoku earthquake and tsunami. As of March 22, 2011, twenty U.S. naval ships, 140 aircraft, and 19,703 Marines and Sailors were involved in humanitarian assistance and disaster relief...
, the United States Navy dispatched the aircraft carrier and other vessels in the Seventh Fleet to fly a series of helicopter operations. A U.S. military spokesperson said that low-level radiation forced a change of course en route to Sendai. The Reagan and sailors aboard were exposed to "a month's worth of natural background radiation from the sun, rocks or soil" in an hour and the carrier was repositioned. Seventeen sailors were decontaminated after they and their three helicopters were found to have been exposed to low levels of radioactivity.
The aircraft carrier was docked for maintenance at Yokosuka Naval Base
United States Fleet Activities Yokosuka
U.S. Fleet Activities Yokosuka, or Commander, Fleet Activities Yokosuka is a United States Navy base, in Yokosuka, Japan. Its mission is to maintain and operate base facilities for the logistic, recreational, administrative support and service of the U.S. Naval Forces Japan, U.S. 7th Fleet and...
, about 280 kilometres (174 mi) from the plant, when instruments detected radiation at 07:00 JST on 15 March. Rear Admiral Richard Wren stated that the nuclear crisis in Fukushima, 320 kilometres (198.8 mi) from Yokosuka, was too distant to warrant a discussion about evacuating the base. Daily monitoring and some precautionary measures were recommended for Yokosuka and Atsugi bases, such as limiting outdoor activities and securing external ventilation systems. As a precaution, the Washington was pulled out of its Yokosuka port later in the week. The Navy also stopped moving its personnel to Japan.
Isotopes of concern
The isotope iodine-131Iodine-131
Iodine-131 , also called radioiodine , is an important radioisotope of iodine. It has a radioactive decay half-life of about eight days. Its uses are mostly medical and pharmaceutical...
is easily absorbed by the thyroid
Thyroid
The thyroid gland or simply, the thyroid , in vertebrate anatomy, is one of the largest endocrine glands. The thyroid gland is found in the neck, below the thyroid cartilage...
. Persons exposed to releases of I-131 from any source have a higher risk for developing thyroid cancer
Thyroid cancer
Thyroid neoplasm is a neoplasm or tumor of the thyroid. It can be a benign tumor such as thyroid adenoma, or it can be a malignant neoplasm , such as papillary, follicular, medullary or anaplastic thyroid cancer. Most patients are 25 to 65 years of age when first diagnosed; women are more affected...
or thyroid disease, or both. Iodine-131 has a short half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
at approximately 8 days, and therefore is an issue mostly in the first weeks after the incident. Children are more vulnerable to I-131 than adults. Increased risk for thyroid neoplasm remains elevated for at least 40 years after exposure. Potassium iodide
Potassium iodide
Potassium iodide is an inorganic compound with the chemical formula KI. This white salt is the most commercially significant iodide compound, with approximately 37,000 tons produced in 1985. It is less hygroscopic than sodium iodide, making it easier to work with...
tablets prevent iodine-131 absorption by saturating the thyroid with non-radioactive iodine. Japan's Nuclear Safety Commission recommended local authorities to instruct evacuees leaving the 20-kilometre area to ingest stable (not radioactive) iodine. CBS News
CBS News
CBS News is the news division of American television and radio network CBS. The current chairman is Jeff Fager who is also the executive producer of 60 Minutes, while the current president of CBS News is David Rhodes. CBS News' flagship program is the CBS Evening News, hosted by the network's main...
reported that the number of doses of potassium iodide available to the public in Japan was inadequate to meet the perceived needs for an extensive radioactive contamination event.
Caesium-137
Caesium-137
Caesium-137 is a radioactive isotope of caesium which is formed as a fission product by nuclear fission.It has a half-life of about 30.17 years, and decays by beta emission to a metastable nuclear isomer of barium-137: barium-137m . Caesium-137 is a radioactive isotope of caesium which is formed...
is also a particular threat because it behaves like potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
and is taken up by cells throughout the body. Additionally, it has a long, 30-year half-life. Cs-137 can cause acute radiation sickness
Radiation Sickness
Radiation Sickness is a VHS by the thrash metal band Nuclear Assault. The video is a recording of a concert at the Hammersmith Odeon, London in 1988. It was released in 1991...
, and increase the risk for cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
because of exposure to high-energy gamma radiation. Internal exposure to Cs-137, through ingestion or inhalation, allows the radioactive material to be distributed in the soft tissues, especially muscle tissue, exposing these tissues to the beta particles and gamma radiation and increasing cancer risk. Prussian blue
Prussian blue
Prussian blue is a dark blue pigment with the idealized formula Fe718. Another name for the color Prussian blue is Berlin blue or, in painting, Parisian blue. Turnbull's blue is the same substance but is made from different reagents....
helps the body excrete caesium-137.
Strontium-90
Strontium-90
Strontium-90 is a radioactive isotope of strontium, with a half-life of 28.8 years.-Radioactivity:Natural strontium is nonradioactive and nontoxic, but 90Sr is a radioactivity hazard...
behaves like calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
, and tends to deposit in bone and blood-forming tissue (bone marrow). 20–30% of ingested Sr-90 is absorbed and deposited in the bone. Internal exposure to Sr-90 is linked to bone cancer, cancer of the soft tissue near the bone, and leukemia. Risk of cancer increases with increased exposure to Sr-90.
Plutonium
Plutonium
Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...
is also present in the MOX fuel
MOX fuel
Mixed oxide fuel, commonly referred to as MOX fuel, is nuclear fuel that contains more than one oxide of fissile material. MOX fuel contains plutonium blended with natural uranium, reprocessed uranium, or depleted uranium. MOX fuel is an alternative to the low-enriched uranium fuel used in the...
of the Unit 3 reactor and in spent fuel rods. Officials at the International Atomic Energy Agency say the presence of MOX fuel does not add significantly to the dangers. Plutonium-239
Plutonium-239
Plutonium-239 is an isotope of plutonium. Plutonium-239 is the primary fissile isotope used for the production of nuclear weapons, although uranium-235 has also been used and is currently the secondary isotope. Plutonium-239 is also one of the three main isotopes demonstrated usable as fuel in...
is particularly long-lived and toxic with a half-life of 24,000 years and remains hazardous for tens of thousands of years. Experts commented that the long-term risk associated with plutonium toxicity is "highly dependent on the geochemistry
Geochemistry
The field of geochemistry involves study of the chemical composition of the Earth and other planets, chemical processes and reactions that govern the composition of rocks, water, and soils, and the cycles of matter and energy that transport the Earth's chemical components in time and space, and...
of the particular site."
Regulatory levels
An overview for regulatory levels in Japan is shown in the table below:| – | Value | Unit | Reference | Comment |
|---|---|---|---|---|
| Yearly exposure of workers | 250 | mSv | Increased from 100 | |
| Spinach | 2 | Bq/g (iodine-131) | possibly a general standard for food | |
| Spinach | 0.5 | Bq/g (caesium-137) | possibly a general standard for food. Increased from 0.37 | |
| Seawater (at discharge) | 0.04 | Bq/mL (iodine-131) | ||
| Seawater (at discharge) | 0.09 | Bq/mL (caesium-137) | ||
| drinking water | 0.1 | Bq/g (iodine-131) | ||
| drinking water | 0.2 | Bq/g (caesium-137) |
Casualties
According to the Japanese Government, over 160,000 people in the general population were screened in March 2011 for radiation exposure and no case was found which affects health. Thirty workers conducting operations at the plant had exposure levels greater than 100 mSv.As of September 2011, six workers at the Fukushima Daiichi site have exceeded lifetime legal limits for radiation and more than 300 have received significant radiation doses.
As of September 2011, there were no deaths or serious injuries due to direct radiation exposures. Cancer deaths due to accumulated radiation exposures cannot be ruled out, and according to one expert, might be in the order of 100 cases.
Frank N. von Hippel
Frank N. von Hippel
Frank N. von Hippel, Professor and Co-Director, Program on Science and Global Security, Princeton University, Woodrow Wilson School of Public and International Affairs.-Positions held:...
, a U.S. scientist, has estimated that “on the order of 1,000” people will die from cancer as a result of their exposure to radiation from the Fukushima Daiichi disaster, that is, an increase of 0.1 percent in the incidence of cancer, and much less than the approximately 20,000 people killed directly by the earthquake and tsunami. Because contaminated milk was “interdicted in Japan” the number of (mostly non-fatal) thyroid cancer cases will probably be less than 1 percent of similar cases at Chernobyl. Von Hippel added that “fear of ionizing radiation could have long-term psychological effects on a large portion of the population in the contaminated areas”.
See also
- 2011 Japanese nuclear accidents2011 Japanese nuclear accidentsThis is a list of articles describing aspects of the nuclear shut-downs, failures, and nuclear meltdowns triggered by the 2011 Tōhoku earthquake and tsunami.-Fukushima nuclear power plants:* Fukushima I Nuclear Power Plant...
- Lists of nuclear disasters and radioactive incidents
- Fukushima 50Fukushima 50Fukushima 50 is the alias given by the media to a group of employees at the crippled Fukushima I Nuclear Power Plant. Following the 2011 Tōhoku earthquake and tsunami, a related series of nuclear accidents resulted in a serious fire at the plant's unit 4 on 15 March 2011, these 50 employees...
External links
- TEPCO News Releases, Tokyo Electric Power Company
- NISA Information update, Nuclear and Industrial Safety AgencyNuclear and Industrial Safety AgencyThe is a Japanese nuclear regulatory and oversight branch of the Agency for Natural Resources and Energy under the Ministry of Economy, Trade and Industry. It was created in 2001 during the 2001 Central Government Reform. It has a main office in Kasumigaseki, Chiyoda, Tokyo that works with the...
, the nuclear safety authority of Japan - IAEA Update on Japan Earthquake, International Atomic Energy AgencyInternational Atomic Energy AgencyThe International Atomic Energy Agency is an international organization that seeks to promote the peaceful use of nuclear energy, and to inhibit its use for any military purpose, including nuclear weapons. The IAEA was established as an autonomous organization on 29 July 1957...
- Navigating Fukushima: Lessons from Chernobyl, Potential Radiation Effects, and Other Health Impacts, Q&A with Dr. Scott Davis about the mechanics of the crisis in Fukushima and how it compares to Chernobyl
- Detailed measurements of radiation levels in air at Fukushima I