Precursors to potential severe core damage accidents: 1980-1981

Technical Report · Sun Jul 01 04:00:00 EDT 1984

OSTI ID:6622592

Cottrell, W B; Minarick, J W; Austin, P N; Hagen, E W; Harris, J D

Descriptions of 58 operational events, reported in Licensee Event Reports (LERs), that occurred at commercial light-water reactors during 1980 to 1981 and are considered to be precursors to potential severe core damage are presented along wih associated event trees, categorization, and subsequent analyses. This study is a continuation of the work presented in NUREG/CR-2497, which somewhat similarly evaluated the 1969 to 1979 events. The current study incorporates improvements that evolved from an assessment of the comments on the earlier report and applies these in the assessment of the LERs that occurred during 1980 to 1981. The report sequentially discusses: (1) the general rationale for this study; (2) the program methods for LER review and documentation; (3) the calculation of function failure probabilities and initiating event frequencies based on precursor data; (4) the use of the conditional probability of subsequent severe core damage estimates to rank precursor events and estimate an average industrywide risk of severe core damage; (5) the conduct of sensitivity analyses on these results; and (6) the application of program results to current concerns pertaining to nuclear power plant risk assessment. There was some apparent decrease in most initiating event frequencies and function failure probabilities in the 1980 to 1981 period as compared with those reported in NUREG/CR-2497. Although it was not possible to conclude that all decreases were statistically significant, in conjunction with other factors they indicate a reduction in the average estimated severe core damage frequency for the nuclear industry for 1980 to 1981 as compared with the 1969 to 1979 period.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6622592
• Report Number(s): NUREG/CR-3591-Vol.1; ORNL/NSIC-217/V1; ON: TI84015741
• Country of Publication: United States
• Language: English

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