Severity, causes and frequencies of pressure vessel thermal shock at U.S. pressurized water reactors (1963–1981)

This article summarizes the results of a study whose purpose was to identify and analyze events at U.S. pressurized water reactors (PWRs) which either resulted in or could be considered as precursors to pressure vessel thermal shock (PVTS). The data base includes 16,000 Licensee Event Reports on 49 PWRs, covering 329 reactor-years from 1963 through 1981. The 99 identified events were assigned to one of five categories of severity. On this basis, 34 of the events were considered significant to PVTS. The events are categorized by cause and by vendor of the plant at which the event occurred. Some probabilistic risk assessment data are also developed.