Davis-Besse
Encyclopedia
Davis-Besse Nuclear Power Station is a nuclear power plant
with a single pressurized water reactor
, also referred to as a light water reactor
. As of 2011, it is operated by the FirstEnergy Nuclear Operating Company subsidiary of FirstEnergy Corp. The power station is located on the southwest shore of Lake Erie
about 10 miles (16.1 km) north of Oak Harbor, Ohio
and is on the north side of Highway 2 just east of Highway 19 on a 954 acres (386.1 ha) site in the Carroll Township. The plant only utilizes 221 acres (89.4 ha), with 733 acres (296.6 ha) devoted to the Ottawa National Wildlife Refuge
. The entrance to the Magee Marsh Wildlife Area is less than a mile east of the power station. The official name according to the U.S. Energy Information Administration
is the Davis-Besse Nuclear Generating Station. It is the 57th commercial power reactor to commence building in the United States of America (construction began on September 1, 1970) and the 50th to come on-line July 31, 1978. The plant was originally jointly owned by Cleveland Electric Illuminating (CEI) and Toledo Edison (TE) and was named for former TE Chairman John K. Davis and former CEI Chairman Ralph M. Besse.
According to the Nuclear Regulatory Commission
, Davis-Besse has been the source of two of the top five most dangerous nuclear incidents in the United States
since 1979.
. The reactor was shut down from 2002 until early 2004 for safety repairs and upgrades, so recent operational statistics are not yet available for the unit.
for the pressurizer to stick open. As of 2005, the NRC considers this to be the fourth highest ranked safety incident.
, used to supply water to the reactor steam generators, shut down. A control room operator then attempted to start the auxiliary (emergency) feedwater pumps. These pumps both tripped on overspeed conditions because of operator error. This incident was originally classified an "unusual event" (the lowest classification the NRC uses) but it was later determined that it should have been classified a "site area emergency".
tornado. The plant's switchyard was damaged and access to external power was disabled. The plant's reactor automatically shut down at 8:43 pm and an alert (the next to lowest of four levels of severity) was declared at 9:18 pm. The plant's emergency diesel generators powered critical facility safety systems until external power could be restored.
) reactor coolant. A breach would have resulted in a loss-of-coolant accident, in which superheated, superpressurized reactor coolant could have jetted into the reactor's containment building
and resulted in emergency safety procedures to protect from core damage or meltdown. Because of the location of the reactor head damage, such a jet of reactor coolant might have damaged adjacent control rod drive mechanisms, hampering or preventing reactor shut-down. As part of the system reviews following the accident, significant safety issues were identified with other critical plant components, including the following:
Under certain scenarios, a reactor rupture would have resulted in core meltdown and/or breach of containment and release of radioactive material. The resulting corrective operational and system reviews and engineering changes took two years. Repairs and upgrades cost $600 million, and the Davis-Besse reactor was restarted in March 2004. The U.S. Justice Department investigated and penalized the owner of the plant over safety and reporting violations related to the incident. The NRC determined that this incident was the fifth most dangerous nuclear incident in the United States since 1979.
, acknowledged a series of safety violations by former workers, and entered into a deferred prosecution agreement
with the U.S. Department of Justice
. The deferred prosecution agreement relates to the March 2002 incident (see above). The deferment granted by the NRC were based on letters from Davis-Besse engineers stating that previous inspections were adequate. However, those inspections were not as thorough as the company suggested, and as proved by the material deficiency discovered later. In any case, because FirstEnergy cooperated with investigators on the matter, they were able to avoid more serious penalties. Therefore, the company agreed to pay fines of $23.7 million, with an additional $4.3 million to be contributed to various groups, including the National Park Service
, the U.S. Fish and Wildlife Service, Habitat for Humanity, and the University of Toledo
as well as to pay some costs related to the federal investigation.
Two former employees and one former contractor were indicted for statements made in multiple documents and one videotape, over several years, for hiding evidence that the reactor pressure vessel was being corroded by boric acid. The maximum penalty for the three is 25 years in prison. The indictment mentions that other employees also provided false information to inspectors, but does not name them.
Davis-Besse operators replaced the original cracked reactor head before restarting in 2004. On March 12, 2010, during a scheduled refueling outage, ultrasonic examinations performed on the control rod
drive mechanism nozzles penetrating the reactor vessel closure head identified that two of the nozzles inspected did not meet acceptance criteria.
FirstEnergy investigators subsequently found new cracks in 24 of 69 nozzles, including one serious enough to leak boric acid. Root cause analysis is currently underway by the Department of Energy
, First Energy, and the NRC to determine the cause of the premature failures.
Crack indications required repair prior to returning the vessel head to service. Control rod drive nozzles were repaired using techniques proven at other nuclear facilities. The plant resumed operation in 2010. The existing reactor vessel head is scheduled for replacement in 2011.
defines two emergency planning zones around nuclear power plants: a plume exposure pathway zone with a radius of 10 miles (16.1 km), concerned primarily with exposure to, and inhalation of, airborne radioactive contamination, and an ingestion pathway zone of about 50 miles (80.5 km), concerned primarily with ingestion of food and liquid contaminated by radioactivity.
The 2010 U.S. population within 10 miles (16.1 km) of Davis-Besse was 18,635, an increase of 14.2 percent in a decade, according to an analysis of U.S. Census data for msnbc.com
. The 2010 U.S. population within 50 miles (80.5 km) was 1,791,856, an increase of 1.4 percent since 2000. Cities within 50 miles (80.5 km) include Sandusky, Ohio
, 22 miles (35.4 km); Toledo, Ohio
26 miles (41.8 km); and Detroit, Michigan
, 50 miles (80.5 km) (distance to the city centers).. U.S. Census data for Canadian population within the area is not available, though Leamington, Ontario
is 39 miles (62.8 km) away, and Windsor, Ontario
(population: 230,000) is 49 miles (78.9 km) from Davis-Besse.
Nuclear power plant
A nuclear power plant is a thermal power station in which the heat source is one or more nuclear reactors. As in a conventional thermal power station the heat is used to generate steam which drives a steam turbine connected to a generator which produces electricity.Nuclear power plants are usually...
with a single pressurized water reactor
Pressurized water reactor
Pressurized water reactors constitute a large majority of all western nuclear power plants and are one of three types of light water reactor , the other types being boiling water reactors and supercritical water reactors...
, also referred to as a light water reactor
Light water reactor
The light water reactor is a type of thermal reactor that uses normal water as its coolant and neutron moderator. Thermal reactors are the most common type of nuclear reactor, and light water reactors are the most common type of thermal reactor...
. As of 2011, it is operated by the FirstEnergy Nuclear Operating Company subsidiary of FirstEnergy Corp. The power station is located on the southwest shore of Lake Erie
Lake Erie
Lake Erie is the fourth largest lake of the five Great Lakes in North America, and the tenth largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time. It is bounded on the north by the...
about 10 miles (16.1 km) north of Oak Harbor, Ohio
Oak Harbor, Ohio
Oak Harbor is a village in Ottawa County, Ohio, United States. Oak Harbor is 30 miles east of Toledo. The population was 2,841 at the 2000 census...
and is on the north side of Highway 2 just east of Highway 19 on a 954 acres (386.1 ha) site in the Carroll Township. The plant only utilizes 221 acres (89.4 ha), with 733 acres (296.6 ha) devoted to the Ottawa National Wildlife Refuge
Ottawa National Wildlife Refuge
The Ottawa National Wildlife Refuge was established in 1961 to preserve habitat for migrating birds. Staff at the refuge also manage Cedar Point and West Sister Island refuges...
. The entrance to the Magee Marsh Wildlife Area is less than a mile east of the power station. The official name according to the U.S. Energy Information Administration
Energy Information Administration
The U.S. Energy Information Administration is the statistical and analytical agency within the U.S. Department of Energy. EIA collects, analyzes, and disseminates independent and impartial energy information to promote sound policymaking, efficient markets, and public understanding of energy and...
is the Davis-Besse Nuclear Generating Station. It is the 57th commercial power reactor to commence building in the United States of America (construction began on September 1, 1970) and the 50th to come on-line July 31, 1978. The plant was originally jointly owned by Cleveland Electric Illuminating (CEI) and Toledo Edison (TE) and was named for former TE Chairman John K. Davis and former CEI Chairman Ralph M. Besse.
According to the Nuclear Regulatory Commission
Nuclear Regulatory Commission
The Nuclear Regulatory Commission is an independent agency of the United States government that was established by the Energy Reorganization Act of 1974 from the United States Atomic Energy Commission, and was first opened January 19, 1975...
, Davis-Besse has been the source of two of the top five most dangerous nuclear incidents in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
since 1979.
Unit One
Unit One is an 879 MWe pressurized water reactor supplied by Babcock and WilcoxBabcock and Wilcox
The Babcock & Wilcox Company is a U.S.-based company that provides design, engineering, manufacturing, construction and facilities management services to nuclear, renewable, fossil power, industrial and government customers worldwide. B&W's boilers supply more than 300,000 megawatts of installed...
. The reactor was shut down from 2002 until early 2004 for safety repairs and upgrades, so recent operational statistics are not yet available for the unit.
Incident history
Over the years of its operation, the plant has experienced several incidents, none of which have resulted in exposure to dangerous levels of radiation.First stuck-open pilot-operated relief valve
On September 24, 1977, the reactor, running at only 9% power, shut down because of a disruption in the feedwater system. This caused the relief valvePilot-operated relief valve
Like other pressure relief valves , pilot operated relief valves are used for emergency relief during overpressure events . The distinction between PORV and conventional PRV is that pilot valves use system pressure to seal the valve...
for the pressurizer to stick open. As of 2005, the NRC considers this to be the fourth highest ranked safety incident.
Loss of feedwater event
On June 9, 1985, the main feedwater pumpsBoiler feedwater pump
A boiler feedwater pump is a specific type of pump used to pump feedwater into a steam boiler. The water may be freshly supplied or returning condensate produced as a result of the condensation of the steam produced by the boiler...
, used to supply water to the reactor steam generators, shut down. A control room operator then attempted to start the auxiliary (emergency) feedwater pumps. These pumps both tripped on overspeed conditions because of operator error. This incident was originally classified an "unusual event" (the lowest classification the NRC uses) but it was later determined that it should have been classified a "site area emergency".
Tornado
On June 24, 1998 the station was struck by an F2Fujita scale
The Fujita scale , or Fujita-Pearson scale, is a scale for rating tornado intensity, based primarily on the damage tornadoes inflict on human-built structures and vegetation...
tornado. The plant's switchyard was damaged and access to external power was disabled. The plant's reactor automatically shut down at 8:43 pm and an alert (the next to lowest of four levels of severity) was declared at 9:18 pm. The plant's emergency diesel generators powered critical facility safety systems until external power could be restored.
Reactor head hole
In March 2002, plant staff discovered that the borated water that serves as the reactor coolant had leaked from cracked control rod drive mechanisms directly above the reactor and eaten through more than six inches (150 mm) of the carbon steel reactor pressure vessel head over an area roughly the size of a football (see photo). This significant reactor head wastage left only 3/8 in of stainless steel cladding holding back the high-pressure (~2500 psi, 17 MPaPascal (unit)
The pascal is the SI derived unit of pressure, internal pressure, stress, Young's modulus and tensile strength, named after the French mathematician, physicist, inventor, writer, and philosopher Blaise Pascal. It is a measure of force per unit area, defined as one newton per square metre...
) reactor coolant. A breach would have resulted in a loss-of-coolant accident, in which superheated, superpressurized reactor coolant could have jetted into the reactor's containment building
Containment building
A containment building, in its most common usage, is a steel or reinforced concrete structure enclosing a nuclear reactor. It is designed, in any emergency, to contain the escape of radiation to a maximum pressure in the range of 60 to 200 psi...
and resulted in emergency safety procedures to protect from core damage or meltdown. Because of the location of the reactor head damage, such a jet of reactor coolant might have damaged adjacent control rod drive mechanisms, hampering or preventing reactor shut-down. As part of the system reviews following the accident, significant safety issues were identified with other critical plant components, including the following:
- the containment sump that allows the reactor coolant to be reclaimed and reinjected into the reactor;
- the high pressure injection pumps that would reinject such reclaimed reactor coolant;
- the emergency diesel generator system;
- the containment air coolers that would remove heat from the containment building;
- reactor coolant isolation valves; and
- the plant's electrical distribution system.
Under certain scenarios, a reactor rupture would have resulted in core meltdown and/or breach of containment and release of radioactive material. The resulting corrective operational and system reviews and engineering changes took two years. Repairs and upgrades cost $600 million, and the Davis-Besse reactor was restarted in March 2004. The U.S. Justice Department investigated and penalized the owner of the plant over safety and reporting violations related to the incident. The NRC determined that this incident was the fifth most dangerous nuclear incident in the United States since 1979.
Criminal prosecutions
On January 20, 2006, the owner of Davis-Besse, FirstEnergy Corporation of Akron, OhioAkron, Ohio
Akron , is the fifth largest city in the U.S. state of Ohio and the county seat of Summit County. It is located in the Great Lakes region approximately south of Lake Erie along the Little Cuyahoga River. As of the 2010 census, the city had a population of 199,110. The Akron Metropolitan...
, acknowledged a series of safety violations by former workers, and entered into a deferred prosecution agreement
Deferred prosecution agreement
A deferred prosecution agreement is a voluntary alternative to adjudication in which a prosecutor agrees to grant amnesty in exchange for the defendant agreeing to fulfill certain requirements...
with the U.S. Department of Justice
United States Department of Justice
The United States Department of Justice , is the United States federal executive department responsible for the enforcement of the law and administration of justice, equivalent to the justice or interior ministries of other countries.The Department is led by the Attorney General, who is nominated...
. The deferred prosecution agreement relates to the March 2002 incident (see above). The deferment granted by the NRC were based on letters from Davis-Besse engineers stating that previous inspections were adequate. However, those inspections were not as thorough as the company suggested, and as proved by the material deficiency discovered later. In any case, because FirstEnergy cooperated with investigators on the matter, they were able to avoid more serious penalties. Therefore, the company agreed to pay fines of $23.7 million, with an additional $4.3 million to be contributed to various groups, including the National Park Service
National Park Service
The National Park Service is the U.S. federal agency that manages all national parks, many national monuments, and other conservation and historical properties with various title designations...
, the U.S. Fish and Wildlife Service, Habitat for Humanity, and the University of Toledo
University of Toledo
The University of Toledo is a public university in Toledo, Ohio, United States. The Carnegie Foundation classified the university as "Doctoral/Research Extensive."-National recognition:...
as well as to pay some costs related to the federal investigation.
Two former employees and one former contractor were indicted for statements made in multiple documents and one videotape, over several years, for hiding evidence that the reactor pressure vessel was being corroded by boric acid. The maximum penalty for the three is 25 years in prison. The indictment mentions that other employees also provided false information to inspectors, but does not name them.
2008 discovery tritium leak
The NRC and Ohio EPA were notified of a tritium leak accidentally discovered during an unrelated fire inspection on October 22, 2008. Preliminary indications suggest radioactive water did not infiltrate groundwater outside plant boundaries2010 Replacement reactor head problems
After the 2002 incident, Davis-Besse purchased a used replacement head from a mothballed reactor in Midland, Michigan.Davis-Besse operators replaced the original cracked reactor head before restarting in 2004. On March 12, 2010, during a scheduled refueling outage, ultrasonic examinations performed on the control rod
Control rod
A control rod is a rod made of chemical elements capable of absorbing many neutrons without fissioning themselves. They are used in nuclear reactors to control the rate of fission of uranium and plutonium...
drive mechanism nozzles penetrating the reactor vessel closure head identified that two of the nozzles inspected did not meet acceptance criteria.
FirstEnergy investigators subsequently found new cracks in 24 of 69 nozzles, including one serious enough to leak boric acid. Root cause analysis is currently underway by the Department of Energy
United States Department of Energy
The United States Department of Energy is a Cabinet-level department of the United States government concerned with the United States' policies regarding energy and safety in handling nuclear material...
, First Energy, and the NRC to determine the cause of the premature failures.
Crack indications required repair prior to returning the vessel head to service. Control rod drive nozzles were repaired using techniques proven at other nuclear facilities. The plant resumed operation in 2010. The existing reactor vessel head is scheduled for replacement in 2011.
Future
The facility's original nuclear operating license expires on April 22, 2017. On August 11, 2006 FirstEnergy Nuclear Operating Company (FENOC) submitted a letter of intent (Adams Accession No. ML062290261). The submission date for the application is August 10, 2010. This initiates a long process that results in an application approval or revocation. Public hearings are a vital part of any application review and information on this process can be found on the U.S. Nuclear Regulatory Commission (NRC) website at NRC.gov. http://www.NRC.gov. The site map contains many valuable linksSeismic risk
The Nuclear Regulatory Commission's estimate of the risk each year of an earthquake intense enough to cause core damage to the reactor at Davis-Besse was 1 in 149,254, according to an NRC study published in August 2010.Surrounding population
The Nuclear Regulatory CommissionNuclear Regulatory Commission
The Nuclear Regulatory Commission is an independent agency of the United States government that was established by the Energy Reorganization Act of 1974 from the United States Atomic Energy Commission, and was first opened January 19, 1975...
defines two emergency planning zones around nuclear power plants: a plume exposure pathway zone with a radius of 10 miles (16.1 km), concerned primarily with exposure to, and inhalation of, airborne radioactive contamination, and an ingestion pathway zone of about 50 miles (80.5 km), concerned primarily with ingestion of food and liquid contaminated by radioactivity.
The 2010 U.S. population within 10 miles (16.1 km) of Davis-Besse was 18,635, an increase of 14.2 percent in a decade, according to an analysis of U.S. Census data for msnbc.com
Msnbc.com
msnbc.com is a news website owned and operated as a joint venture by NBCUniversal and Microsoft.In addition to original content from its news staff, msnbc.com is the news website for the NBC News family, with content from the cable television news channel MSNBC, NBC shows such as Today, NBC Nightly...
. The 2010 U.S. population within 50 miles (80.5 km) was 1,791,856, an increase of 1.4 percent since 2000. Cities within 50 miles (80.5 km) include Sandusky, Ohio
Sandusky, Ohio
Sandusky is a city in the U.S. state of Ohio and the county seat of Erie County. It is located in northern Ohio and is situated on the shores of Lake Erie, almost exactly half-way between Toledo to the west and Cleveland to the east....
, 22 miles (35.4 km); Toledo, Ohio
Toledo, Ohio
Toledo is the fourth most populous city in the U.S. state of Ohio and is the county seat of Lucas County. Toledo is in northwest Ohio, on the western end of Lake Erie, and borders the State of Michigan...
26 miles (41.8 km); and Detroit, Michigan
Detroit, Michigan
Detroit is the major city among the primary cultural, financial, and transportation centers in the Metro Detroit area, a region of 5.2 million people. As the seat of Wayne County, the city of Detroit is the largest city in the U.S. state of Michigan and serves as a major port on the Detroit River...
, 50 miles (80.5 km) (distance to the city centers).. U.S. Census data for Canadian population within the area is not available, though Leamington, Ontario
Leamington, Ontario
Leamington is a municipality in Essex County, southern Ontario, Canada, and has a population of 31,113. It includes Point Pelee, the southernmost point of mainland Canada. It has a large H. J. Heinz Company factory and is known as the "Tomato Capital of Canada", with 4 km² of this crop in the...
is 39 miles (62.8 km) away, and Windsor, Ontario
Windsor, Ontario
Windsor is the southernmost city in Canada and is located in Southwestern Ontario at the western end of the heavily populated Quebec City – Windsor Corridor. It is within Essex County, Ontario, although administratively separated from the county government. Separated by the Detroit River, Windsor...
(population: 230,000) is 49 miles (78.9 km) from Davis-Besse.