The methodology of Probabilistic Safety Assessment (PSA) was originated from the Reactor Safety Study (RSS) or WASH-1400 report published in 1975.  PSA employs the theory of statistics and probability and the technique of fault trees and event trees to quantify the risk to the public associated with operating of a nuclear power reactor.  The Three Mile Island nuclear power plant incident in 1979 proved that the PSA technique is very effective in identifying the vulnerability of nuclear power reactors.  The nuclear industries around the world have used the techniques to improve the safety of nuclear power plant.  The risk insight from PSA study is adopted by regulatory bodies around the world to allocate the resources of safety oversight.
 
Traditionally, the analyses involved in PSA can be divided into three major steps (or levels).  In Level I, the accident scenarios and core melt frequency are quantified using fault trees and event trees.  The reliability data analysis and human reliability are part of the analysis of Level I.  In Level II analysis, the containment failure probability of the accident scenarios identified in Level I study are analyzed and the accident source terms are quantified.  In Level III analysis, the risk to the public for each source term category identified in Level II analysis is quantified.

All the major elements involved in PSA will be covered in this course. The major focus will be on the statistical and probability theory, the techniques of fault trees and event trees analysis, human reliability analysis, and external event tree analysis.  The work involved in Level II and Level III will be covered briefly.  Finally, the concept of risk insight regulation is covered.