Citation

Ahmed S, Metcalf DR. Reliab. Eng. 1983; 6(4): 211-227.

Copyright

(Copyright © 1983, Elsevier Publishing)

DOI

10.1016/0143-8174(83)90005-7

PMID

unavailable

Abstract

Quantification of risk of large technological systems, such as nuclear power plants, is often done on the basis of point estimates. However, one source of confusion and controversy is the choice of point estimates for the basic event unavailabilities and the interpretation of the system unavailability thus obtained. It is shown through several examples that the system unavailability obtained by using median values of the basic event unavailabilities results in a very optimistic estimate and does not represent the central tendency of the TOP event probability distribution. On the other hand, the use of mean values of the basic event unavailability results in a conservative system unavailability.