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A probabilistic approach to the evaluation of the PTS issue [electronic resource].

Published
Rockville, Md. : U.S. Nuclear Regulatory Commission, 1991.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description
Pages: (28 pages) : digital, PDF file
Additional Creators
Oak Ridge National Laboratory, U.S. Nuclear Regulatory Commission, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
An integrated probabilistic approach for the evaluation of the pressurized-thermal-shock (PTS) issue was developed at the Oak Ridge National Laboratory (ORNL) at the request of the Nuclear Regulatory Commission (NRC). The purpose was to provide a method for identifying dominant plant design and operating features, evaluating possible remedial measures and the validity of the NRC PTS screening criteria, and to provide an additional tool for estimating vessel life expectancy. The approach was to be integrated in the sense that it would include the postulation of transients; estimates of their frequencies of occurrence; systems analyses to obtain the corresponding primary-system pressure, down-comer coolant temperature, and fluid-film heat-transfer coefficient adjacent to the vessel wall; and a probabilistic fracture-mechanics analysis, using the latter data as input. A summation of the products of frequency of transient and conditional probability of failure for all postulated transients provides an estimate of frequency of vessel failure. In the process of developing the integrated pressurized-thermal-shock (IPTS) methodology, three specific plant analyses were conducted. The results indicate that the NRC screening criteria may not be appropriate for all US pressurized water reactor (PWR) plants; that is, for some PWRs, the calculated mean frequency of vessel failure corresponding to the screening criteria may be greater than the maximum permissible value in Regulatory Guide 1.154. A recent view of the ORNL IPTS study, which was completed in 1985, indicates that there are a number of areas in which the methodology can and should be updated, but it is not clear whether the update will increase or decrease the calculated probabilities. 31 refs., 2 tabs.
Report Numbers
E 1.99:conf-910602-13
conf-910602-13
Subject(s)
Other Subject(s)
Note
Published through SciTech Connect.
01/01/1991.
"conf-910602-13"
"DE91009125"
American Society of Mechanical Engineers (ASME) pressure vessels and piping conference, San Diego, CA (USA), 23-27 Jun 1991.
Cheverton, R.D.; Selby, D.L.
Funding Information
AC05-84OR21400
View MARC record | catkey: 14370984