WASH-1400, 'The Reactor Safety Study', was a report produced in 1975 for the
Nuclear Regulatory Commission
The Nuclear Regulatory Commission (NRC) is an independent agency of the United States government tasked with protecting public health and safety related to nuclear energy. Established by the Energy Reorganization Act of 1974, the NRC began operat ...
by a committee of specialists under Professor Norman Rasmussen. It "generated a storm of criticism in the years following its release". In the years immediately after its release, WASH-1400 was followed by a number of reports that either peer reviewed its methodology or offered their own judgments about probabilities and consequences of various events at commercial reactors. In at least a few instances, some offered critiques of the study's assumptions, methodology, calculations, peer review procedures, and objectivity.John Byrne and Steven M. Hoffman (1996). ''Governing the Atom: The Politics of Risk'', Transaction Publishers, p. 147. A succession of reports, including
NUREG-1150 NUREG-1150 "Severe Accident Risks: An Assessment for Five U.S. Nuclear Power Plants", published December 1990 by the Nuclear Regulatory Commission (NRC) is a follow-up to the WASH-1400 and CRAC-II safety studies that employs the methodology of plan ...
, the
State-of-the-Art Reactor Consequence Analyses The State-of-the-Art Reactor Consequence Analyses (SOARCA) is a study of nuclear power, nuclear power plant nuclear safety, safety conducted by the Nuclear Regulatory Commission. The purpose of the SOARCA is assessment of possible impact on populat ...
and others, have carried-on the tradition of PRA and its application to commercial power plants.
The report correctly foresaw the impact a
tsunami
A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater exp ...
could have on a nuclear power station. It concluded that "Some plants are located on the sea shore where the possibility of tsunami, and waves and high water levels due to hurricanes exist. The plant design in these cases must accommodate the largest waves and water levels that can be expected. Such events were assessed to represent negligible risks." (Section 5.4.6 "Other external causes")
Overview
WASH-1400 considered the course of events that might arise during a serious accident at a (then) large modern
Light water reactor
The light-water reactor (LWR) is a type of thermal-neutron reactor that uses normal water, as opposed to heavy water, as both its coolant and neutron moderator; furthermore a solid form of fissile elements is used as fuel. Thermal-neutron react ...
. It estimated the radiological consequences of these events, and the probability of their occurrence, using a
fault tree
Fault tree analysis (FTA) is a type of failure analysis in which an undesired state of a system is examined. This analysis method is mainly used in safety engineering and reliability engineering to understand how systems can fail, to identify ...
/
event tree An event tree is an inductive analytical diagram in which an event is analyzed using Boolean logic to examine a chronological series of subsequent events or consequences. For example, event tree analysis is a major component of nuclear reactor safet ...
approach. This technique is called
Probabilistic Risk Assessment
Probabilistic risk assessment (PRA) is a systematic and comprehensive methodology to evaluate risks associated with a complex engineered technological entity (such as an airliner or a nuclear power plant) or the effects of stressors on the environm ...
(PRA). The report concluded that the risks to the individual posed by nuclear power stations were acceptably small, compared with other tolerable risks. Specifically, the report concluded, using the methods and resources and knowledge available at the time, that the probability of a complete core meltdown is about 1 in 20,000 per reactor per year.
The study was peer-reviewed by the 'Lewis Committee' in 1977, which broadly endorsed the methodology as the best available, but cautioned that the risk figures were subject to large uncertainty.
The methods used were comparatively simple by today's standards and based on early understanding of key phenomenology. Amidst a period of intensive (and extensive) research and discussion, inspired in part by the
Three Mile Island accident
The Three Mile Island accident was a partial meltdown of the Three Mile Island, Unit 2 (TMI-2) reactor in Pennsylvania, United States. It began at 4 a.m. on March 28, 1979. It is the most significant accident in U.S. commercial nuclea ...
, work continued on PRA including
NUREG-1150 NUREG-1150 "Severe Accident Risks: An Assessment for Five U.S. Nuclear Power Plants", published December 1990 by the Nuclear Regulatory Commission (NRC) is a follow-up to the WASH-1400 and CRAC-II safety studies that employs the methodology of plan ...
and an ongoing study being performed by the
Nuclear Regulatory Commission
The Nuclear Regulatory Commission (NRC) is an independent agency of the United States government tasked with protecting public health and safety related to nuclear energy. Established by the Energy Reorganization Act of 1974, the NRC began operat ...
called the State-of-the-Art Reactor Consequence Analyses (SOARC Specific Studies were also made of two plants at Zion and Indian Point—the so-called Z/IP Study.
The PRA methodology became generally followed as part of the nuclear safety, safety-assessment of all modern
nuclear power plant
A nuclear power plant (NPP) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a electric generator, generato ...
s. In the 1990s, all U.S. nuclear power plants submitted PRAs to the NRC under the Individual Plant Examination progra and five of these were the basis for the 1991 NUREG-1150.
According to Table 6-3 on pg. 112 of WASH-1400, individual persons have a less than 1 in 5,000,000,000 (Tbl 6-3, pg. 112) chance of dying on a yearly basis from the operation of 100 nuclear power plants in the United States. This is less than yearly risk of being struck by lightning and being killed (1 in 20,000,000, Tbl 6-3, pg. 112), being in a fatal auto collision (1 in 3,000 chance of dying, Tbl 6-3, pg. 112), or any other accident risk mentioned in WASH-1400.
WASH-1400 is now NUREG-75/014.
Criticism and debate
In the years since its publication, WASH-1400 has occasioned much discussion of its methods and has seen the rise of competing judgments about the probabilities and consequences of adverse events in commercial nuclear power reactors. A panel of scientists organized by the American Physical Society (APS) "found much to criticize" in the WASH-1400 report. The panel noted that fatality estimates had considered only deaths during the first 24 hours after an accident, although other pathways (e.g., via radioactive cesium) could result in environmental exposures after the acute phase of an accident and could expose large populations to adverse effects, albeit at small doses. Any cancers that might arise might not show up until years after the accident. The APS reviewers also criticized the report’s methods for predicting the performance of emergency cooling systems.Office of Technology Assessment. (1984). Nuclear power in an Age of Uncertainty. Chapter Public Attitudes Toward Nuclear Power, pp. 218–219. /ref>
One particular focus of discussion has been the size of the probabilities, posited in WASH-1400, of the occurrence of the various accidents and events. While a 1982 report by Science Applications Inc. (SAI) found those of WASH-1400 to be underestimates, a contemporaneous report by the
Institute of Nuclear Power Operations
The Institute of Nuclear Power Operations (INPO), headquartered in Atlanta, GA, is an organization established in 1979 by the U.S. nuclear power industry in response to recommendations by the Kemeny Commission Report, following the investigation ...
found SAI's to be too high by a factor of 30.
The
Union of Concerned Scientists
The Union of Concerned Scientists (UCS) is a nonprofit science advocacy organization based in the United States. The UCS membership includes many private citizens in addition to professional scientists. Anne Kapuscinski, Professor of Environmenta ...
released a 150-page report critiquing the WASH-1400 report, and in June 1976, the House Subcommittee on Energy and Environment held hearings on the validity of the report's findings. As a result of these hearings, NRC agreed to have a review group examine the validity of the report's conclusions.
In a 1978 report,
Harold Lewis
Harold ("Hal") Warren Lewis (born October 1, 1923 at the Center for History of Physics,
Harold Lewis
Harold ("Hal") Warren Lewis (born October 1, 1923 at the Center for History of Physics,
of the
University of California
The University of California (UC) is a public land-grant research university system in the U.S. state of California. The system is composed of the campuses at Berkeley, Davis, Irvine, Los Angeles, Merced, Riverside, San Diego, San Franci ...
concluded that "the uncertainties in WASH-1400's estimates of the probabilities of severe accidents were in general, greatly understated". Rassmussen observed that the likelihood of a core melt, as estimated in WASH-1400 and NUREG 1150, were in close agreement and their uncertainty bands overlappe
In 1979, The NRC issued a policy statement in which it accepted numerous criticisms of WASH-1400 raised by the Lewis Report, and it withdrew any endorsement of the executive summary.John Byrne and Steven M. Hoffman (1996). ''Governing the Atom: The Politics of Risk'', Transaction Publishers, p. 148.
See also
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CRAC-II
CRAC-II is both a computer code (titled Calculation of Reactor Accident Consequences) and the 1982 report of the simulation results performed by Sandia National Laboratories for the Nuclear Regulatory Commission. The report is sometimes referred to ...
(1982)
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Nuclear power
Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced b ...
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Nuclear reactor accidents in the United States
The United States Government Accountability Office reported more than 150 incidents from 2001 to 2006 of nuclear plants not performing within acceptable safety guidelines. According to a 2010 survey of energy accidents, there have been at least 5 ...
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Nuclear safety in the United States
Nuclear safety in the United States is governed by federal regulations issued by the Nuclear Regulatory Commission (NRC). The NRC regulates all nuclear plants and materials in the United States except for nuclear plants and materials controlled by ...
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NUREG-1150 NUREG-1150 "Severe Accident Risks: An Assessment for Five U.S. Nuclear Power Plants", published December 1990 by the Nuclear Regulatory Commission (NRC) is a follow-up to the WASH-1400 and CRAC-II safety studies that employs the methodology of plan ...
(1991)
*
State-of-the-Art Reactor Consequence Analyses The State-of-the-Art Reactor Consequence Analyses (SOARCA) is a study of nuclear power, nuclear power plant nuclear safety, safety conducted by the Nuclear Regulatory Commission. The purpose of the SOARCA is assessment of possible impact on populat ...
(2012)
*
WASH-740 WASH-740 was a report published by the U.S. Atomic Energy Commission (USAEC) in 1957. This report, called "Theoretical Possibilities and Consequences of Major Accidents in Large Nuclear Power Plants" (also known as "The Brookhaven Report"), estimate ...