Analysis of core damage frequency from internal events: Peach Bottom, Unit 2

Abstract

This document contains the internal event initiated accident sequence analyses for Peach Bottom, Unit 2; one of the reference plants being examined as part of the NUREG-1150 effort by the Nuclear Regulatory Commission. NUREG-1150 will document the risk of a selected group of nuclear power plants. As part of that work, this report contains the overall core damage frequency estimate for Peach Bottom, Unit 2, and the accompanying plant damage state frequencies. Sensitivity and uncertainty analyses provide additional insights regarding the dominant contributors to the Peach Bottom core damage frequency estimate.The mean core damage frequency at Peach Bottom was calculated to be 8.2E-6. Station blackout type accidents (loss of all AC power) were found to dominate the overall results. Anticipated Transient Without Scram accidents were also found to be non-negligible contributors.The numerical results are largely driven by common mode failure probability estimates and to some extent, human error.Because of significant data and analysis uncertainties in these two areas (important, for instance, to the most dominant scenario in this study), it is recommended that the results of the uncertainty and sensitivity analyses be considered before any actions are taken based on this analysis.iii/iv

Accident Sequence Evaluation Program: Human reliability analysis procedure

“…Water Reactor (PWR) Unit 1 (Bertucio et a l , 1987a), Peach Bottom Boiling Water Reactor (BWR) Unit 2 (Kolaczkowski et al, 1986), Sequoyah PWR Unit 1 (Bertucio et al, 1987b), and the Grand Gulf BWR Unit 1 (Drouin et al, 1987). The above reports are all volumes in NUREG/CR-4550, which also includes a report on methodology (Harper et al, 1987a) and a summary report (Harper et al, 1987b).…”

Analysis of Uncertainties in Interactive Probabilistic Safety Analysis (PSA) Models

“…= E[NEW/REF] = E[NEW * 1/REF] which can be written from Ref. 6 as E[SF] = E[NEW] E[l/REF] + pa1u2(4) where p is the correlation between NEW and l/REF, ul is the standard deviation of NEW, and a, is the standard deviation of 1/REF. (Note that the correlation between NEW and 1/REF is not the same as the correlation between NEW and REF.…”