March 15th, 2011 – Plant Seismic information to Support NRC Hearing on Wednesday

Author: No Comments Share:

From: Stutzke, Martin
Sent: Tuesday, March 15, 2011 1:44 PM
To: Mahoney, Michael; Glitter, Joseph; Hiland, Patrick
Cc: Kammerer, Annie; Ake, Jon
Subject: Plant Seismic information to Support NRC Hearing on Wednesday
Attachments: SSE Exceed and SCDF.xlsx

I’ve prepared a spreadsheet that provides the following information for each operating plant:

1. Safe shutdown earthquake (SSE)

2. Annual frequency of exceeding the SSE

For Western US plants (Columbia, Diablo Canyon, San Onofre, and Palo Verde), this information is based on the seismic hazard curve for peak ground acceleration as reported in the IPEEE. For the Central and Eastern US (CEUS) plants, this information is based on the 2008 US Geological Survey
seismic hazard curves (adjusted for site-specific soil amplification) for peak ground acceleration, 10 Hz, 5 Hz, and 1 Hz spectral frequencies as developed for the Safety/Risk Assessment of Generic Issue ,1 99 (GI-199).

3. The review-level earthquake (RLE) used in the IPEEE
This information was obtained from the IPEEE submittals, and is reported in NUREG-1742. The RLE is only applicable to those plants that used seismic margins analysis (SMA) to respond to the IPEEE (Generic Letter 88-20, Supplement 4). The RLE is specified in terms of the high confidence of low probability of failure (HCLPF) for peak ground acceleration. The HCLPF is the acceleration value at which there is a 1 % probability of core damage. The RLE is not applicable to plants that performed seismic PRAs.

4. The seismic core-damage frequency
For most Western US plants (Columbia, Diablo Canyon, and San Onofre), this information is based on – IPEEE submittals as summarized in NUREG-1742. For Palo Verde, I made an estimate using the methods developed for GI-199. For the CEUS plants, this information was developed in the Safety/Risk Assessment of G1-1 99.

5. The method used in the IPEEE to assess seismic risk, as reported in NUREG-1742
The attached spreadsheet also provides fleetwide summary statistics for the frequencies of exceeding the SSE and the seismic core-damage frequencies (average, median, minimum, maximum, etc.).

Please note that the GI-199 Safety/Risk Assessment is publically available (ML100270582). NUREG-1742 is available in the Electronic Reading Room on the public website. IPEEEs are no longer publically available (following the 9/11/2001 event).


Martin A. Stutzke
Senior Technical Advisor for PRA Technologies
Division of Risk Assessment
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
(301) 251-7614



Previous Article

Post-Fukushima, Japanese Official sees crisis as war between humans and technology

Next Article

March 15th, 2011 – I am walking to the 6th floor to get permission to work on this.