An Illustration of Matrix Formulation for a Probabilistic Risk-Assessment Study

A matrix formulation is described and numerically illustrated to calculate the public risk and identify the dominant contributors to it arising from the operation of a nuclear power plant. The matrix methodology is used as a superstructure in a probabilistic risk-assessment study to organize the calculated probabilities and to facilitate the analysis and documentation effort. The matrix structure is built to manipulate the large amount of data arising from event and fault-tree analysis and other supporting analyses. It lends itself easily to computerization and provides an analytic capability to identify dominant contributors to risk. It is a useful tool for aiding sensitivity analyses and also a potential formalism for standardization of risk-assessment studies. This tool is already used in the two recent comprehensive nuclear power plant risk-assessment efforts, the Zion and Indian Point Safety Studies.