WASH-1400

WASH-1400, also known as the Reactor Safety Study, was a report commissioned by the United States Atomic Energy Commission (AEC) and published in 1975. Its primary purpose was to assess the probabilities and potential consequences of nuclear reactor accidents in U.S. commercial light-water reactors (LWRs). Led by Professor Norman Rasmussen of MIT, the study employed probabilistic risk assessment (PRA) methodology to quantify the risks associated with various accident scenarios.

The report concluded that the risks associated with nuclear power plant accidents were very low, significantly lower than other technological risks faced by society. It estimated the probability of a core meltdown at one in 20,000 reactor-years. While the study was influential in shaping early perceptions of nuclear safety, it also faced significant criticism, particularly regarding the uncertainties inherent in its probabilistic modeling, the treatment of common cause failures, and the potential for human error.

Following its publication, the WASH-1400 report was subjected to a thorough review by the Lewis Committee, which identified several limitations and recommended improvements to the risk assessment methodology. The NRC subsequently withdrew its endorsement of the Executive Summary's quantitative risk estimates but continued to use the report's methodology as a basis for safety assessments. Despite its flaws, WASH-1400 played a crucial role in the development of modern probabilistic risk assessment techniques and continues to be a significant historical document in the field of nuclear safety. It highlighted the importance of considering a range of accident scenarios and quantifying the associated risks.