4.0 Summary of Major DCISC Review Topics, 17th Annual Report - July 1, 2006 thru June 30, 2007
4.20 Earthquakes and Tsunamis
4.20.1 Overview and Previous Activities
This section of the report provides updates on recent seismic events, tsunamis or related matters that could affect DCPP.
In previous reports the DCISC has reviewed with PG&E earthquakes occurring in the DCPP vicinity of California as well as seismic designs, analyses, and activities related to DCPP. This has included updates to PG&E’s Long Term Seismic Program which is an NRC license condition requiring PG&E to monitor and evaluate seismic events world-wide which could potentially affect DCPP design.
In the previous period the DCISC reviewed the following:
- December 22, 2003 San Simeon Earthquake Update
- DCPP Seismic Monitoring System
- Tsunami Threats to DCPP
The DCPP response to the December 22, 2003 San Simeon Earthquake appeared satisfactory. There was no damage to the plant which operated normally through the event. One lingering issue, an exceedence of the expected vertical seismic response at the top of the Unit 1 Containment, has been evaluated by PG&E and reported to the NRC. The exceedence was well within the design basis of the plant. Although subject to tsunamis, they are included in the design basis, and a recent evaluation shows that they are not a threat that would exceed the design basis.
4.20.2 Current Period Activities
There were no seismic or tsunami items for review during the current reporting period. The DCISC understands that DCPP has completed its final tsunami report for the Pacific Ocean and plans to review it during the upcoming reporting period.
The DCISC plans to review with PG&E during the next reporting period the July 16, 2007 6.8 magnitude earthquake in Japan near Kashiwazaki-Kariwa nuclear station.
4.20.3 Conclusions and Recommendations
- Conclusions:
- There was no seismic or tsunami activity affecting DCPP in this reporting period; however, the DCISC plans to review with PG&E during the next period the July 16, 2006 Japanese earthquake near the Kashiwazaki-Kariwa nuclear station and lessons learned that could be relevant to DCPP.
- Recommendations: None