(A) sensitivity analysis of key uncertainty issues of the PWR containment event tree analysis

Abstract

A sensitivity analysis for the PWR containment response issues and the levels of each issue was performed in this study. These issues and levels were used at Brookhaven National Laboratory on Zion power plant containment response analysis for postulated severe accident. The EVNTREISS code, originally developed at Sandia National Laboratory was used for this study with a few modifications and improvements of the original code to use on a personal computer. The modified code was verified by comparison with the old and new calculations. Through the sensitivity analysis, the effects of eight uncertainty issues and levels on the release category uncertainty for each plant damage state were quantified. The results of sensitivity analysis show that the most sensitive and uncertain issue to the early containment failure which is a major contributor to the risk is the pressure increase due to direct containment heating and steam spike. The other issues of major