ML14204A619
| ML14204A619 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 07/21/2014 |
| From: | Heacock D Dominion Nuclear Connecticut |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 14-132A | |
| Download: ML14204A619 (4) | |
Text
Dominion Nuclear Connecticut, Inc.
5000 Dominion Boulevard, Glen Allen, VA 23060 D-minion f
Web Address: wwwv.dom.com July 21, 2014 U.S. Nuclear Regulatory Commission Serial No.
14-132A Attention: Document Control Desk NL&OS/WDC RO Washington, DC 20555 Docket Nos.
50-336/423 License Nos.
DPR-65 NPF-49 DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNITS 2 AND 3 RESPONSE TO MARCH 12, 2012 INFORMATION REQUEST SUPPLEMENTAL INFORMATION RELATED TO THE SEISMIC HAZARD AND SCREENING REPORT FOR RECOMMENDATION 2.1
References:
- 1. NRC Letter, "Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3, of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident," dated March 12, 2012.
- 2. Electric Power Research Institute (EPRI) Report 1025287, Seismic Evaluation Guidance: Screening, Prioritization, and Implementation Details (SPID) for Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic.
- 3. EPRI Report 3002000704, Augmented Approach for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic.
- 4. Dominion letter to NRC, "Millstone Power Station Units 2 and 3 Response to March 12, 2012 Information Request - Seismic Hazard and Screening Report (CEUS Sites) for Recommendation 2.1," dated March 31, 2014.
- 5. NRC Letter, 'Electric Power Research Institute Final Draft Report XXXXXX, "Seismic Evaluation Guidance: Augmented Approach for the Resolution of Near-Term Task Force Recommendation 2.1: Seismic," as an Acceptable Alternative to the March 12, 2012, Information Request for Seismic Reevaluations,' dated May 7, 2013.
- 6. NRC Letter, "Screening and Prioritization Results Regarding Information Pursuant To Title 10 of the Code of Federal Regulations 50.54(F) Regarding Seismic Hazard Re-Evaluations for Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident", dated May 9, 2014.
- 7. NRC Letter, "Request for Additional Information Associated with Near-Term Task Force Recommendation 2.1, Seismic Hazard and Screening Report," dated July 16, 2014.
On March 12, 2012, the Nuclear Regulatory Commission (NRC) issued Reference 1 to all power reactor licensees and holders of construction permits in active or deferred status. of Reference 1 requested each addressee in the Central and Eastern United States (CEUS) to submit a Seismic Hazard and Screening Report.
Dominion submitted the Seismic Hazard and Screening Report for Millstone Power Station Units 2 (MPS2) and 3 (MPS3) to the NRC in Reference 4. The report provided
Serial No. 14-132A Docket Nos. 50-336/423 Page 2 of 4 the basis for both units to screen out of performing seismic risk evaluations in accordance with the guidance in the SPID (Reference 2). This screening was based on demonstrating that the plant capacity spectra for MPS2 and MPS3 from the Individual Plant Examination for External Events (IPEEE) exceed the new ground motion response spectrum (GMRS) in the 1 to 10 Hz range.
Dominion demonstrated the adequacy of the IPEEE programs, in accordance with the criteria in the SPID, for both MPS2 and MPS3 in Reference 4. In Reference 6, the NRC stated that for MPS3, "...the Licensee has demonstrated IPEEE plant capacity, consistent with endorsed guidance, bounds the re-evaluated hazard." For MPS2, NRC requested additional information related to IPEEE adequacy (Reference 7). Dominion provided the response to the request in Reference 8, and there are no further open issues related to IPEEE adequacy for the Millstone units.
In Reference 1, the NRC requested interim evaluations and actions "...to address higher seismic hazard.... prior to completion of risk evaluation". Section 1 of the Augmented Approach guidance (Reference
- 3) states that "...this report addresses interim evaluations.... to be implemented prior to performing complete plant seismic risk evaluations." The NRC endorsement of the Augmented Approach guidance (Reference 5), states that the Expedited Seismic Evaluation Process (ESEP) can provide seismic margin "...while more detailed and comprehensive plant seismic risk evaluations are being performed."
Consistent with the guidance contained in Reference 3, the Seismic Hazard and Screening Report (Reference 4) indicated that MPS2 and MPS3 should screen-in for the performance of the ESEP. However, the spectral amplitudes of the new GMRS for MPS2 and MPS3 are sufficiently low that interim seismic risk evaluations for ESEP do not provide commensurate safety benefit.
Dominion considers that the resource-intensive interim evaluations per the Augmented Approach guidance for ESEP, which were intended to address high seismic hazards prior to completion of a seismic risk evaluation, are not warranted for MPS2 or MPS3. From a seismic safety perspective, the MPS2 IPEEE, which used the EPRI seismic margin assessment (SMA) approach, has already demonstrated that the plant can safely shut down with redundant success paths with plant seismic capacity above the GMRS.
Similarly for MPS3, the IPEEE plant high-confidence-of-low-probability-of-failure (HCLPF) capacity is above the GMRS, which demonstrates the capability of a safe shutdown in a seismic event.
Further, the new GMRS is only marginally greater than the safe-shutdown earthquake (SSE) spectra for MPS2 and MPS3.
Thus, an ESEP review per the Reference 3 guidance would only consider a minimal increase above SSE in seismic demand, and in fact would be bounded by the IPEEE evaluations and modifications already conducted.
The review of a limited set of components to these demand levels, in accordance with the ESEP guidance, would not provide a significant increase in safety insight or indication of seismic margin for the units beyond what was already provided by the IPEEE Program.
Since MPS2 and MPS3 have demonstrated seismic capacities above the GMRS, Dominion concludes the benefit from the performance of an ESEP is not commensurate
Serial No. 14-132A Docket Nos. 50-336/423 Page 3 of 4 with resource expenditure and is furthermore bounded by the already conducted IPEEE evaluations and modifications.
Therefore, Dominion does not intend to perform the ESEP for MPS2 and MPS3. The action to perform a relay chatter review and Spent Fuel Pool evaluation, per the guidance in References 2 and 3, as indicated in the Seismic Hazard and Screening Report, remains unchanged.
If you have any questions regarding this information, please contact Wanda Craft at (804) 273-4687.
Sincerely, David A. Heacock President and Chief Nuclear Officer IkI L. H0111 Dominion Nuclear Connecticut, Inc.
NOTARY PIULIC l commonwee!th of Virginia
~~Reg.*#
140542 my Commission Expires.May 31, 2016 COMMONWEALTH OF VIRGINIA 0
COUNTY OF HENRICO The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by David A. Heacock, who is President and Chief Nuclear Officer of Dominion Nuclear Connecticut, Inc. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that company, and that the statements in the document are true to the best of his knowledge and belief.
Acknowledged before me this
=Tday of
\\J
, 2014.
My Commission Expires:
5-31-1 NotaryA.
Pici Notary Public Commitments made in this letter: No new regulatory commitments
Serial No. 14-132A Docket Nos. 50-336/423 Page 4 of 4 cc:
U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd Suite 100 King of Prussia, PA 19406-2713 Mohan C. Thadani Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 08 B 1 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station 50.54fSeismic.Resource@nrc.gov