WASH-1400是美国原子能委员会1975年发表的《核电站风险报告》，用了70人/年的工作量，耗资300万美元，相当于建造一座1000兆瓦核电站投资的1%。

1974年美国原子能委员会在没有核电站事故先例的情况下，应用系统安全工程分析方法，提出了著名的《核电站风险报告》（WASH-1400），并被以后发生的核电站事故所证实。

当前，大多数工业发达国家已将安全评价作为工厂设计和选址、系统设计、工艺过程、事故预防措施及制订应急计划的重要依据。

Englisn Introduction

WASH-1400, '(The) Reactor Safety Study' was a report produced in 1975for the USNRCby a committee of specialists under Professor Norman Rasmussen. It is thus often referred to as the Rasmussen Report. It considered the course of events which might arise during a serious accident at a (then) large modern Light water reactor. It estimated the radiological consequences of these events, and the probability of their occurrence, using a fault tree/event tree approach. This technique is called Probabilistic Risk Assessment(PRA).

The report concluded that the risks to the individual posed by such stations were acceptably small, compared with other tolerable risks. Specifically, the report concluded 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 and overly-pessimistic by today's standards, and based on early understanding of key phenomenology. Following a period of intensive (and expensive) research and discussion, inspired in part by Three Mile Island, WASH-1400 was replaced in due course first by NUREG-1150and now by a new study being performed by the Nuclear Regulatory Commission. 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 safety-assessmentof all modern nuclear power plants. In the 1990s, all US nuclear power plants submitted PRAs to the NRC under the Individual Plant Examination program *, and five of these were the basis for the 1991 NUREG-1150.

is now NUREG-75/014.