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Title: Comparison of methods for uncertainty analysis of nuclear-power-plant safety-system fault-tree models. [PWR; BWR]

Technical Report ·
DOI:https://doi.org/10.2172/6215909· OSTI ID:6215909

A comparative evaluation is made of several methods for propagating uncertainties in actual coupled nuclear power plant safety system faults tree models. The methods considered are Monte Carlo simulation, the method of moments, a discrete distribution method, and a bootstrap method. The Monte Carlo method is found to be superior. The sensitivity of the system unavailability distribution to the choice of basic event unavailability distribution is also investigated. The system distribution is also investigated. The system distribution is especially sensitive to the choice of symmetric versus asymmetric basic event distributions. A quick-and dirty method for estimating percentiles of the system unavailability distribution is developed. The method identifies the appropriate basic event distribution percentiles that should be used in evaluating the Boolean system equivalent expression for a given fault tree model to arrive directly at the 5th, 10th, 50th, 90th, and 95th percentiles of the system unavailability distribution.

Research Organization:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
DOE Contract Number:
W-7405-ENG-36
OSTI ID:
6215909
Report Number(s):
NUREG/CR-3263; LA-9729-MS; ON: DE83012220
Resource Relation:
Other Information: Portions are illegible in microfiche products
Country of Publication:
United States
Language:
English