Radioactive scrap metal
Encyclopedia
Radioactive scrap metal is the situation when radioactive material enters the metal recycling process and contaminates scrap metal
.
is lost or stolen
. Such objects often end up in the scrap metal industry, as people mistake them for harmless bits of metal. The International Atomic Energy Agency
has provided guides for scrap metal collectors on what a sealed source might look like. The best known example of this type of event is the Goiânia accident
, in Brazil
.
While some lost source accidents have not involved the scrap metal industry, they are still good examples of the likely scale and scope of a lost source accident. For example, the Red Army
left sources behind in Lilo. Another case occurred at Yanango where a radiography
source was lost and at Gilan, Iran
a radiography source harmed a welder
.
Radioactive sources have a wide range of uses in medicine and industry, it is common for the design (and nature) of a source to be tailored to the application so it is impossible to state with confidence what the "typical" source looks like or contains. For instance, antistatic devices include beta and alpha emitters: polonium
containing devices have been used to eliminate static electricity
in such devices as paint spraying equipment. An overview of the gamma sources used for radiography
can be seen at Radiographic equipment
, and it is reasonable to consider this to be a good overview of small to moderate gamma sources.
) a group of three men were responsible for such an incident: they burgled a radioactive waste
store to steal scrap metal. One of them picked up a metal pipe and placed it in his pocket. This metal pipe was a very strong 137Cs source which gave a high localised dose to the man’s leg (1800 Sv local, 4 Sv whole body). He was admitted a few days later to hospital where he claimed to have had an accident in the woods. He died shortly after as a result of whole body irradiation from the source. Before going to the hospital, he left the source in his house where it then irradiated other members of his family and his dog (which died as a result). His son suffered a localised radiation burn (local dose of 25 Sv, whole body 3.6 Gy) which resulted in the amputation of fingers, when he inadvertently handled the source when looking for tools to repair his bicycle. When a medical doctor saw these burns it was understood that an ionising radiation accident was in progress. The man's wife got a 500 mSv dose while his mother got a 2.25 Sv dose.
It is interesting to note that the scrap metal industry was involved twice in this: the caesium source being originally found in a shipment of scrap metal which was brought into the country (at that point it was thought to be a 60Co source based on half thickness measurements). The source was placed in the radioactive waste store for safekeeping, which was subsequently entered by the men who were intent on stealing scrap metal.
teletherapy source was lost , attempts were made by some scrap metal workers to recycle the metal. During this time humans were subject to irradation by the source.
It was found that at the edge of the scrap yard the dose rate was about 1 to 10 mSv hr−1. The exact location of the source in the scrap yard was determined using a fluorescent screen which acted as a scintillator
. This was held on the end of a long pole.
was difficult both because the source was opened, and the active material was water soluble. The event in Mexico wherein cobalt-60
was spilled in an almost identical event led to a very different pattern of contamination since the cobalt in such a source is normally in the form of cobalt metal alloyed with some nickel
to improve the mechanical properties of the active metal. If such a source is abused, then the cobalt metal fragments do not tend to dissolve in water or become very mobile. If a cobalt
or iridium
source is lost at a ferrous metal scrapyard then it is often the case that the source will enter a furnace, the radioactive metal will melt and contaminate the steel from this furnace. In the United States, some buildings have been demolished because of the level of cobalt-60 in the steel used to make them. Also, some of the steel which was rendered radioactive in the Mexican event was used to make table legs.
used for steel scrap, it is more likely that the caesium will contaminate the fly ash
or dust from the furnace, while radium
is likely to stay in the ash or slag
. The United States Environmental Protection Agency
provide data about the fate of different contaminating elements in a scrap furnace . Four different fates for the element exist: the element can stay in the metal (as with cobalt
and ruthenium
); the element can enter the slag
(as in lanthanide
s, actinide
s and radium
); the element can enter the furnace dust or fly ash (as with caesium
), which accounts for around 5%; or the element can leave the furnace and pass through the bag house to enter the air (as with iodine
).
In the case of some high value scrap metals it is possible to decontaminate scrap metal
, but this is best done long before the metal goes to a scrap yard.
, aluminium
scrap and flux
in a furnace. This is heated to form molten aluminium. From the furnace three main streams are obtained, metal product, dross
(metal oxides and halides which is skimmed off the molten metal product) and off gases which go to the baghouse
. The cooled waste gasses are then allowed out into the environment.
, is refined in one furnace before being refined further in an electrochemical process. The furnace generates impure metal, slag
, dust
and gases. The dust accumulates in a bag house, while the gases are vented to the atmosphere. The impure metal from the furnace may be refined in an electrochemical process.
If the copper refinery includes an electrochemical process after the furnace, then unwanted elements are removed from the impure metal and deposited as anode slime.
which was contaminated with lead-210 entered the jewelry industry. This was from gold seeds which had held radon
-222 which had been melted down (after the radon had decayed). The daughters of the radon are still radioactive.
pot and transport this to the radioactive waste
store. It is noteworthy that in this instance the source recovery workers wore rubber glove
s, but more importantly failed to use tongs
. Gamma ray
s obey the inverse square law so by slightly increasing the distance between the recovery worker and the source the dose rate experienced by the worker can be reduced. In the recovery of lost sources the International Atomic Energy Agency
consider that it is best to plan the recovery first, and to consider using a crane
or other device to place shielding (such as pallet of bricks or a concrete block) near the source to allow the recovery worker to approach it while being protected by the added shielding.
Scrap Metal
Scrap Metal were a band from Broome, Western Australia who played rock music with elements of country and reggae. The members had Aboriginal, Irish, Filipino, French, Chinese, Scottish, Indonesian and Japanese heritage. The band toured nationally as part of the Bran Nue Dae musical and with...
.
Overview
A lost source accident is one where a radioactive objectOrphan source
An orphan source is a self-contained radioactive source that is no longer under proper regulatory control.The United States Nuclear Regulatory Commission defines an orphan source more exactly as:...
is lost or stolen
Theft
In common usage, theft is the illegal taking of another person's property without that person's permission or consent. The word is also used as an informal shorthand term for some crimes against property, such as burglary, embezzlement, larceny, looting, robbery, shoplifting and fraud...
. Such objects often end up in the scrap metal industry, as people mistake them for harmless bits of metal. 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...
has provided guides for scrap metal collectors on what a sealed source might look like. The best known example of this type of event is the Goiânia accident
Goiânia accident
The Goiânia accident was a radioactive contamination accident that occurred on September 13, 1987, at Goiânia, in the Brazilian State of Goiás after an old radiotherapy source was taken from an abandoned hospital site in the city...
, in Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
.
While some lost source accidents have not involved the scrap metal industry, they are still good examples of the likely scale and scope of a lost source accident. For example, the Red Army
Red Army
The Workers' and Peasants' Red Army started out as the Soviet Union's revolutionary communist combat groups during the Russian Civil War of 1918-1922. It grew into the national army of the Soviet Union. By the 1930s the Red Army was among the largest armies in history.The "Red Army" name refers to...
left sources behind in Lilo. Another case occurred at Yanango where a radiography
Radiography
Radiography is the use of X-rays to view a non-uniformly composed material such as the human body. By using the physical properties of the ray an image can be developed which displays areas of different density and composition....
source was lost and at Gilan, Iran
Iran
Iran , officially the Islamic Republic of Iran , is a country in Southern and Western Asia. The name "Iran" has been in use natively since the Sassanian era and came into use internationally in 1935, before which the country was known to the Western world as Persia...
a radiography source harmed a welder
Welder
A welder is a tradesman who specializes in welding materials together. The materials to be joined can be metals or varieties of plastic or polymer...
.
Radioactive sources have a wide range of uses in medicine and industry, it is common for the design (and nature) of a source to be tailored to the application so it is impossible to state with confidence what the "typical" source looks like or contains. For instance, antistatic devices include beta and alpha emitters: polonium
Polonium
Polonium is a chemical element with the symbol Po and atomic number 84, discovered in 1898 by Marie Skłodowska-Curie and Pierre Curie. A rare and highly radioactive element, polonium is chemically similar to bismuth and tellurium, and it occurs in uranium ores. Polonium has been studied for...
containing devices have been used to eliminate static electricity
Static electricity
Static electricity refers to the build-up of electric charge on the surface of objects. The static charges remain on an object until they either bleed off to ground or are quickly neutralized by a discharge. Static electricity can be contrasted with current electricity, which can be delivered...
in such devices as paint spraying equipment. An overview of the gamma sources used for radiography
Radiography
Radiography is the use of X-rays to view a non-uniformly composed material such as the human body. By using the physical properties of the ray an image can be developed which displays areas of different density and composition....
can be seen at Radiographic equipment
Radiographic equipment
This is a page devoted to the basic equipment used for radiographic work, both medical and industrial.- Photon sources :There are many types of sources for high energy X-ray and gamma photons.- X-ray sources :...
, and it is reasonable to consider this to be a good overview of small to moderate gamma sources.
Tammiku (Estonia)
In Tammiku (EstoniaEstonia
Estonia , officially the Republic of Estonia , is a state in the Baltic region of Northern Europe. It is bordered to the north by the Gulf of Finland, to the west by the Baltic Sea, to the south by Latvia , and to the east by Lake Peipsi and the Russian Federation . Across the Baltic Sea lies...
) a group of three men were responsible for such an incident: they burgled a radioactive waste
Radioactive waste
Radioactive wastes are wastes that contain radioactive material. Radioactive wastes are usually by-products of nuclear power generation and other applications of nuclear fission or nuclear technology, such as research and medicine...
store to steal scrap metal. One of them picked up a metal pipe and placed it in his pocket. This metal pipe was a very strong 137Cs source which gave a high localised dose to the man’s leg (1800 Sv local, 4 Sv whole body). He was admitted a few days later to hospital where he claimed to have had an accident in the woods. He died shortly after as a result of whole body irradiation from the source. Before going to the hospital, he left the source in his house where it then irradiated other members of his family and his dog (which died as a result). His son suffered a localised radiation burn (local dose of 25 Sv, whole body 3.6 Gy) which resulted in the amputation of fingers, when he inadvertently handled the source when looking for tools to repair his bicycle. When a medical doctor saw these burns it was understood that an ionising radiation accident was in progress. The man's wife got a 500 mSv dose while his mother got a 2.25 Sv dose.
It is interesting to note that the scrap metal industry was involved twice in this: the caesium source being originally found in a shipment of scrap metal which was brought into the country (at that point it was thought to be a 60Co source based on half thickness measurements). The source was placed in the radioactive waste store for safekeeping, which was subsequently entered by the men who were intent on stealing scrap metal.
Samut Prakarn (Thailand)
At Samut Prakarn a 15.7 TBq (425 Ci) cobalt-60Cobalt-60
Cobalt-60, , is a synthetic radioactive isotope of cobalt. Due to its half-life of 5.27 years, is not found in nature. It is produced artificially by neutron activation of . decays by beta decay to the stable isotope nickel-60...
teletherapy source was lost , attempts were made by some scrap metal workers to recycle the metal. During this time humans were subject to irradation by the source.
It was found that at the edge of the scrap yard the dose rate was about 1 to 10 mSv hr−1. The exact location of the source in the scrap yard was determined using a fluorescent screen which acted as a scintillator
Scintillator
A scintillator is a special material, which exhibits scintillation—the property of luminescence when excited by ionizing radiation. Luminescent materials, when struck by an incoming particle, absorb its energy and scintillate, i.e., reemit the absorbed energy in the form of light...
. This was held on the end of a long pole.
137Cs vs 60Co (solubility in water)
The clean up operation for the Goiânia accidentGoiânia accident
The Goiânia accident was a radioactive contamination accident that occurred on September 13, 1987, at Goiânia, in the Brazilian State of Goiás after an old radiotherapy source was taken from an abandoned hospital site in the city...
was difficult both because the source was opened, and the active material was water soluble. The event in Mexico wherein cobalt-60
Cobalt-60
Cobalt-60, , is a synthetic radioactive isotope of cobalt. Due to its half-life of 5.27 years, is not found in nature. It is produced artificially by neutron activation of . decays by beta decay to the stable isotope nickel-60...
was spilled in an almost identical event led to a very different pattern of contamination since the cobalt in such a source is normally in the form of cobalt metal alloyed with some nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
to improve the mechanical properties of the active metal. If such a source is abused, then the cobalt metal fragments do not tend to dissolve in water or become very mobile. If a cobalt
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
or iridium
Iridium
Iridium is the chemical element with atomic number 77, and is represented by the symbol Ir. A very hard, brittle, silvery-white transition metal of the platinum family, iridium is the second-densest element and is the most corrosion-resistant metal, even at temperatures as high as 2000 °C...
source is lost at a ferrous metal scrapyard then it is often the case that the source will enter a furnace, the radioactive metal will melt and contaminate the steel from this furnace. In the United States, some buildings have been demolished because of the level of cobalt-60 in the steel used to make them. Also, some of the steel which was rendered radioactive in the Mexican event was used to make table legs.
Ferrous scrap
In the case of a caesium source being melted in an electric arc furnaceElectric arc furnace
An electric arc furnace is a furnace that heats charged material by means of an electric arc.Arc furnaces range in size from small units of approximately one ton capacity up to about 400 ton units used for secondary steelmaking...
used for steel scrap, it is more likely that the caesium will contaminate the fly ash
Fly ash
Fly ash is one of the residues generated in combustion, and comprises the fine particles that rise with the flue gases. Ash which does not rise is termed bottom ash. In an industrial context, fly ash usually refers to ash produced during combustion of coal...
or dust from the furnace, while radium
Radium
Radium is a chemical element with atomic number 88, represented by the symbol Ra. Radium is an almost pure-white alkaline earth metal, but it readily oxidizes on exposure to air, becoming black in color. All isotopes of radium are highly radioactive, with the most stable isotope being radium-226,...
is likely to stay in the ash or slag
Slag
Slag is a partially vitreous by-product of smelting ore to separate the metal fraction from the unwanted fraction. It can usually be considered to be a mixture of metal oxides and silicon dioxide. However, slags can contain metal sulfides and metal atoms in the elemental form...
. The United States Environmental Protection Agency
United States Environmental Protection Agency
The U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
provide data about the fate of different contaminating elements in a scrap furnace . Four different fates for the element exist: the element can stay in the metal (as with cobalt
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
and ruthenium
Ruthenium
Ruthenium is a chemical element with symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most chemicals. The Russian scientist Karl Ernst Claus discovered the element...
); the element can enter the slag
Slag
Slag is a partially vitreous by-product of smelting ore to separate the metal fraction from the unwanted fraction. It can usually be considered to be a mixture of metal oxides and silicon dioxide. However, slags can contain metal sulfides and metal atoms in the elemental form...
(as in lanthanide
Lanthanide
The lanthanide or lanthanoid series comprises the fifteen metallic chemical elements with atomic numbers 57 through 71, from lanthanum through lutetium...
s, actinide
Actinide
The actinide or actinoid series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium.The actinide series derives its name from the group 3 element actinium...
s and radium
Radium
Radium is a chemical element with atomic number 88, represented by the symbol Ra. Radium is an almost pure-white alkaline earth metal, but it readily oxidizes on exposure to air, becoming black in color. All isotopes of radium are highly radioactive, with the most stable isotope being radium-226,...
); the element can enter the furnace dust or fly ash (as with 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...
), which accounts for around 5%; or the element can leave the furnace and pass through the bag house to enter the air (as with 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....
).
Scrap Metal
Scrap Metal were a band from Broome, Western Australia who played rock music with elements of country and reggae. The members had Aboriginal, Irish, Filipino, French, Chinese, Scottish, Indonesian and Japanese heritage. The band toured nationally as part of the Bran Nue Dae musical and with...
, but this is best done long before the metal goes to a scrap yard.
Aluminium scrap
It is normal to place siliconSilicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
, aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
scrap and flux
Flux
In the various subfields of physics, there exist two common usages of the term flux, both with rigorous mathematical frameworks.* In the study of transport phenomena , flux is defined as flow per unit area, where flow is the movement of some quantity per time...
in a furnace. This is heated to form molten aluminium. From the furnace three main streams are obtained, metal product, dross
Dross
Dross is a mass of solid impurities floating on a molten metal. It appears usually on the melting of low-melting-point metals or alloys such as tin, lead, zinc or aluminium, or by oxidation of the metal. It can also consist of impurities such as paint leftovers...
(metal oxides and halides which is skimmed off the molten metal product) and off gases which go to the baghouse
Baghouse
A baghouse or fabric filter is an air pollution control device that removes particulates out of air or gas released from commercial processes or combustion for electricity generation. Power plants, steel mills, pharmaceutical producers, food manufactures, chemical producers and other industrial...
. The cooled waste gasses are then allowed out into the environment.
Copper scrap
It is normal that good-quality scrap copper, such as that from a nuclear plantNuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...
, is refined in one furnace before being refined further in an electrochemical process. The furnace generates impure metal, slag
Slag
Slag is a partially vitreous by-product of smelting ore to separate the metal fraction from the unwanted fraction. It can usually be considered to be a mixture of metal oxides and silicon dioxide. However, slags can contain metal sulfides and metal atoms in the elemental form...
, dust
Dust
Dust consists of particles in the atmosphere that arise from various sources such as soil dust lifted up by wind , volcanic eruptions, and pollution...
and gases. The dust accumulates in a bag house, while the gases are vented to the atmosphere. The impure metal from the furnace may be refined in an electrochemical process.
Gold scrap
In the early part of the 20th century in the USA, goldGold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
which was contaminated with lead-210 entered the jewelry industry. This was from gold seeds which had held radon
Radon
Radon is a chemical element with symbol Rn and atomic number 86. It is a radioactive, colorless, odorless, tasteless noble gas, occurring naturally as the decay product of uranium or thorium. Its most stable isotope, 222Rn, has a half-life of 3.8 days...
-222 which had been melted down (after the radon had decayed). The daughters of the radon are still radioactive.
Sealed vs. unsealed source
In the Tammiku event, where a caesium source of similar strength was stolen, the accident site was easy to clean because the source remained sealed. All that needed to be done was to pick the source up, place it in a leadLead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
pot and transport this to the radioactive waste
Radioactive waste
Radioactive wastes are wastes that contain radioactive material. Radioactive wastes are usually by-products of nuclear power generation and other applications of nuclear fission or nuclear technology, such as research and medicine...
store. It is noteworthy that in this instance the source recovery workers wore rubber glove
Rubber glove
A rubber glove is a glove made out of rubber. Rubber gloves can be unsupported or supported . Its primary purpose is protection of the hands while performing tasks involving chemicals. Rubber gloves are worn during dishwashing to protect the hands from detergent and allow the use of hotter water...
s, but more importantly failed to use tongs
Tongs
Tongs are used for gripping and lifting tools, of which there are many forms adapted to their specific use. Some are merely large pincers or nippers, but the greatest number fall into three classes:...
. Gamma ray
Gamma ray
Gamma radiation, also known as gamma rays or hyphenated as gamma-rays and denoted as γ, is electromagnetic radiation of high frequency . Gamma rays are usually naturally produced on Earth by decay of high energy states in atomic nuclei...
s obey the inverse square law so by slightly increasing the distance between the recovery worker and the source the dose rate experienced by the worker can be reduced. In the recovery of lost sources 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...
consider that it is best to plan the recovery first, and to consider using a crane
Crane (machine)
A crane is a type of machine, generally equipped with a hoist, wire ropes or chains, and sheaves, that can be used both to lift and lower materials and to move them horizontally. It uses one or more simple machines to create mechanical advantage and thus move loads beyond the normal capability of...
or other device to place shielding (such as pallet of bricks or a concrete block) near the source to allow the recovery worker to approach it while being protected by the added shielding.