Chubu Electric Power Company, Incorporated
Regarding Facts and Recurrence Prevention Measures for Seismic Hazard Evaluation by the Statistical Green’s Function Method
An internal investigation report addressing concerns over inappropriate methods in the process of seismic hazard assessment for the Onagawa Nuclear Power Station’s compliance with new regulatory standards, including recommendations for recurrence prevention. It discusses selection methods (1–4), post-processing, and tuning, highlighting issues in discussions with NRA and management responses.
Key Figures
- Description regarding the existence or absence of records for minimizing residuals at each meeting of the adequacy review and evidence trail creation
- Counts of simulated ground-motion candidate data such as Ss-D/Ss-N (e.g., 600・300・900)
- Cases of changes to seismic motion evaluation periods due to changes in fault initiation points or source models
AI要約
Section Heading
This report verifies the factual sequence related to the seismic hazard assessment for the Onagawa Nuclear Power Station, pointing out multiple issues in the selection of representative waves in statistical Green’s function and hybrid synthesis methods, setting connection periods for seismic motion evaluation, and post-processing (e.g., filtering). It notes that external expert comments were not reflected in the meeting materials for the suitability review, and cases where NRA cross-checks were bypassed or undervalued are listed.
Section 2 Heading
As recurrence prevention measures, proposals include reform of corporate governance, improvement of organizational culture, regular external technical audits, fostering a modest corporate climate, ensuring psychological safety, establishing internal rules, and ensuring traceability. Emphasis is placed on overcoming独自の正当化理論 (self-justification theory) and strengthening surveillance, and implementing external checks.
Chubu Electric Power Company, Incorporated
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