Uncertainty evaluation of blackout initiated accident sequences of a typical PHWR

Probabilistic Safety Assessment (PSA) is a systematic and comprehensive methodology to evaluate risk associated with a complex engineered technological entity. Accuracy of PSA is influenced greatly by methodology, uncertainties in data/models, unjustified assumptions and incompleteness in analysis. The Risk Analysis (RA) model attempts to simulate reality, thus it is inevitable that there will be simplifying assumptions and idealizations of rather complex processes and phenomena. These simplifications and idealizations will generate uncertainties. The impact of these uncertainties must be addressed if the RA is to serve as a tool in the decision making process.Present work involves uncertainty analysis for station blackout initiated accident sequence. We have compared PSA study results of two codes, FaultTree+ (Isograph Inc.), a commercial software, and PMC (Program for Monte Carlo), developed in-house. Both these codes are based on Monte Carlo methods.We have developed another code, PFA (Program for Fuzzy Arithmetic) for PSA study. It is based on fuzzy arithmetic principle. We have compared Monte Carlo and Fuzzy arithmetic method by using PMC and PFA results. A comparative performance is reported in this work.

► Risk analysis.
► Monte Carlo.
► FaultTree+
► PHWR.