Relay Chatter and Operator Response After a Large Earthquake. An Improved PRA (Probabilistic Risk Assessment) Methodology with Case Studies.

摘要

The report addresses methodological weaknesses in the PRA systems analysis used for studying post-earthquake relay chatter and for quantifying human response under high stress. An improved PRA methodology for relay-chatter analysis is developed, and its use is demonstrated through analysis of the Zion-1 and LaSalle-2 reactors as case studies. The demonstration analysis is intended to show that the methodology can be applied in actual cases. The analysis relies on SSMRP-based methodologies and data bases. For both Zion-1 and LaSalle-2, it is assumed that loss of offsite power (LOSP) occurs after a large earthquake and that there are no operator recovery actions. The report also presents an improved PRA methodology for quantifying operator error under high-stress conditions such as after a large earthquake. Single-operator error rates are developed, and a case study involving an 8-step procedure (establishing feed-and-bleed in a PWR after an earthquake-initiated accident) is used to demonstrate the methodology.