ML14079A039
| ML14079A039 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 03/10/2014 |
| From: | Dent J Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML14079A039 (7) | |
Text
SEntergy Entergy Nuclear Operations, Inc.
Pilgrim Nuclear Power Station 600 Rocky Hill Road Plymouth, MA 02360 John A. Dent, Jr.
Site Vice President March 10, 2014 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk 11555 Rockville Pike Rockville, MD 20852
SUBJECT:
Entergy's Supplemental Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Seismic Aspects of Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident - 1.5 Year Response for CEUS Sites Pilgrim Nuclear Power Station Docket No. 50-293 License No. DPR-35 LETTER NUMBER 2.14.019
REFERENCE:
- 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", March 12, 2012 (ML12053A340)
- 2. NRC Letter, "Endorsement of EPRI Final Draft Report 1025287, Seismic Evaluation Guidance", dated February 15, 2013 (ML12319A074)
- 3.
EPRI Report 1025287, "Seismic Evaluation Guidance: Screening, Prioritization and Implementation Details (SPID) for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic", dated November, 2012 (ML12333A170)
- 4. NEI Letter to NRC, "Proposed Path Forward for NTTF Recommendation 2.1: Seismic Reevaluations", dated April 9, 2013 (ML13101A345)
- 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, 20.12, Information Request for Seismic Reevaluations", dated May 7, 2013 (ML13106A331)
- 6. Entergy Letter to NRC, "Entergy's Response to NRC Request For Information Pursuant to 10 CFR 50.54(f) Regarding the Seismic Aspects of Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident", dated April 29, 2013 (PNPS Letter 2.13.039)
A, -.
PNPS Letter 2.14.019 Page 2 of 3
- 7. Entergy Letter to NRC, "Entergy's Response to NRC Request For Information Pursuant to 10 CFR 50.54(f) Regarding the Seismic Aspects of Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident - 1.5 Year Response for CEUS Sites",
dated September 12, 2013 (PNPS Letter 2.13.071)
Dear Sir or Madam:
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 written response consistent with the requested seismic hazard evaluation information (items 1 through 7) by September 12, 2013. On February 15, 2013, NRC issued Reference 2, endorsing the Reference 3 industry guidance for responding to Reference 1. Section 4 of Reference 3 identifies the detailed information to be included in the seismic hazard evaluation submittals.
On April 9, 2013, NEI submitted Reference 4 to NRC, requesting NRC agreement to delay submittal of some of the CEUS seismic hazard evaluation information so that an update to the EPRI (2004, 2006) ground motion attenuation model could be completed and used to develop that information. NEI proposed that descriptions of subsurface materials and properties and base case velocity profiles (items 3a and 3b in Section 4 of Reference 3) be submitted to NRC by September 12, 2013, with the remaining seismic hazard and screening information submitted to NRC by March 31, 2014. In Reference 5, NRC agreed with this recommendation. Reference 6 contained Entergy's commitment to follow the approach described in Reference 4.
The attachment to this letter contains revised information regarding site specific soil data to be used as input to the seismic hazard evaluation work being performed by Pilgrim Nuclear Power Station (PNPS). Specifically, Table 1 R of the attachment to this letter supersedes the originally submitted Table 1 of Reference 7. Based on this revised input data, the base case velocity profiles will be updated by Electric Power Research Institute (on behalf of PNPS) and included in the PNPS final seismic hazard screening report to be submitted to NRC by March 31, 2014 in accordance with Reference 5.
Should you have any questions concerning the content of this letter, please contact Mr.
Joseph R. Lynch, Manager, Regulatory Assurance at (508) 830-8403.
This letter contains no new regulatory commitments.
I declare under penalty of perjury that the foregoing is true and correct; executed on March 10, 2014.
Sincerely a iDent Jr.
Site Vice President JAD/rmb
PNPS Letter 2.14.019 Page 3 of 3
Attachment:
Pilgrim Nuclear Power Station Updated Subsurface Soil Profile Information for Development of New Site Specific Ground Motion Response Spectra cc:
Mr. William M. Dean Regional Administrator, Region 1 U.S. Nuclear Regulatory Commission 2100 Renaissance Boulevard, Suite 100 King of Prussia, PA 19406-1415 U. S. Nuclear Regulatory Commission Director, Office of Nuclear Reactor Regulation One White Flint North 11555 Rockville Pike Rockville, MD 20852 Ms. Nadiyah Morgan, Project Manager Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop O-8C2A Washington, DC 20555 Mr. John Giarrusso Jr.
Planning, Preparedness & Nuclear Section Chief Mass. Emergency Management Agency 400 Worcester Road Framingham, MA 01702 U. S. Nuclear Regulatory Commission ATTN: Robert J. Fretz Jr.
Mail Stop OWFN/4A15A 11555 Rockville Pike Rockville, MD 20852-2378 U. S. Nuclear Regulatory Commission ATTN: Robert L. Dennig Mail Stop OWFN/10E1 11555 Rockville Pike Rockville, MD 20852-2378 NRC Senior Resident Inspector Pilgrim Nuclear Power Station
ATTACHMENT to PNPS Letter 2.14.019 Pilgrim Nuclear Power Station UPDATED SUBSURFACE SOIL PROFILE INFORMATION FOR DEVELOPMENT OF NEW SITE SPECIFIC GROUND MOTION RESPONSE SPECTRA
Attachment to PNPS Letter 2.14.019 Pilgrim Nuclear Power Station - GMRS Considerations In support of the seismic hazard screening process required by the Fukushima 50.54f Letter, Pilgrim Nuclear Power Station (PNPS) received its new site specific Ground Motion Response Spectra (GMRS) from EPRI on Jan 14, 2014 (Ref.Al). The GMRS was developed by EPRI in accordance with the NRC endorsed guidance document EPRI 1025287 (known as SPID).
The new PNPS GMRS was found to have similar amplitude and shape as compared to what was expected based on 2010 EPRI estimates (Ref.A2). However, the spectral peak, which was originally estimated to occur at approx. 25 Hz, has shifted to a lower frequency range such that it now results in significantly higher accelerations in the upper portion of the 1-10 Hz screening range.
Efforts by Entergy seismic experts to understand the shift in the location of the spectral peak have revealed that the shear wave velocity values used for the bedrock layers have a significant influence. Specifically, it appears that the use of lower bedrock shear wave velocities as input to the new GMRS has contributed heavily to the shift of the spectral peak.
PNPS provided the site specific soil information to EPRI for the new GMRS development via Report PNPS-SGC-01 Rev.0. The PNPS report included a tabulation of shear wave velocities that was developed by GEl Consultants (Ref.A3) based on review of existing plant documents (no new field surveys or testing). EPRI utilized a shear wave velocity of 6000 fps for PNPS bedrock based on the PNPS/GEI input. By comparison, the 2010 EPRI estimate used a bedrock shear wave velocity of >9000 fps, consistent with the industry standard used in attenuation models for Central and Eastern US.
PNPS FSAR Section 2.5.2.4.2 includes a description of the site bedrock. The bedrock consists of Dedham granodiorite (igneous rock similar to granite). It is described as "slightly weathered to a depth of 6 feet but competent with infrequent joints and fractures below this depth".
Additional research and further discussions with GEl Consultants (Ref.A5) suggest that the 6000 fps value originally specified by GEl is appropriate for the upper weathered layer of bedrock but a higher value is appropriate for the underlying "competent" granodiorite. A study performed by Dames & Moore for PNPS's Design & Analysis Report (Ref.A4) resulted in a shear wave velocity of 10,500 fps for the granodiorite bedrock, based on site specific field and laboratory testing. Other miscellaneous online sources support the Dames & Moore value as reasonable for solid igneous bedrock.
Included below are the original soil input data (Table 1) that was provided to EPRI via Report PNPS-SGC-01 Rev.0 and a revised version (Table 1 R) to be used as input to a rerun of the PNPS GMRS analysis.
The expectation is not that the proposed refinement of the GMRS will result in PNPS screening out of the Seismic Probabilistic Risk Assessment (SPRA) phase of the 50.54f seismic risk re-evaluation program. On the contrary, it is expected that the refined GMRS will still exceed the Page 1 of 3
Attachment to PNPS Letter 2.14.019 PNPS Safe Shutdown Earthquake (SSE) and High Confidence of a Low Probability of Failure (HCLPF) spectra within the 1-10 Hz screening range. However, it is of great importance that an accurate description of PNPS's seismic hazard be communicated to NRC and other external stakeholders. This will ensure appropriate prioritization of PNPS with regard to SPRA scheduling and prevent unjustified alarm by stakeholders when GMRS results are made public.
Table 1: Original shear wave velocities provided to EPRI via PNPS-SGC-01 Depth Elevation Soil/Rock Shear Wave Range El Velocity (feet)
MSL Description (fps) 0
+22 feet Surface Grade 0 to 20
+22 feet to +2 feet Compacted Fill 675 20 to 48
+2 feet to -26 feet Compacted Fill 900 48
-26 feet Reactor Building Foundation (SSE control point) 48 to 90
-26 feet to -68 feet Glacial Outwash 1800 90 +
-68 feet and below Bedrock 6000 Table 1 R: Refined shear wave velocities for rerun of GMRS analysis Depth Elevation Soil/Rock Shear Wave Range Elevation Velocity (feet)
MSL Description (fps) 0
+22 feet Surface Grade 0 to 20
+22 feet to +2 feet Compacted Fill 675 20 to 48
+2 feet to -26 feet Compacted Fill 900 48
-26 feet Reactor Building Foundation (SSE control point) 48 to 90
-26 feet to -68 feet Glacial Outwash 1800 90 to 96
-68 feet to -74 feet Weathered Upper Bedrock Layer 6000 96+
-74 feet and below Competent Granodiorite Bedrock 10500
References:
Al. Pilgrim Seismic Hazard and Screening Report, Project 1041, Lettis Consultants International Inc., 1/14/2014 A2. Updated Seismic Hazard Results for the Arkansas, Fitzpatrick, Grand Gulf, Indian Point, Pilgrim, River Bend, Vermont Yankee, and Waterford Sites, EPRI, August 2010 A3. Review of Soil Properties for Site Response Analysis - Pilgrim Nuclear Power Station, GEl Consultants Inc., 5/30/2012 A4. PNPS Design & Analysis Report, Amendment 3, Docket 50-293, December 1967 (Includes Dames & Moore - Engineering Seismology Report)
A5. GEl 1/27/14 Email Concurrence for Revised Shear Wave Velocity (attached below)
Page 2 of 3
Attachment to PNPS Letter 2.14.019 From:
Paster, Mike <MPaster@qeiconsu]tants.com>
Sent Monday, January 27, 2014 12:29 PM To:
Small, David S, Mogolesko, Fred Cc:
Larnbe, Robert Subject RE: Pilgrim Station Bedrock Shear Wave Velocity Attachments-Shear Wave Velocity for PNPS Bedrock.doc* PNPS Design & Analysis Report Cexcerpts).pdf
- All, I have reviewed the information you provided. Based on the data provided in the PNPS Design & Analysis Report, I concur that it is reasonable to use a shear wave velocity of 6,000 ft/sec for the top 6 ft of rock, and a shear wave velocity of :10,500 ft/sec for the rock below that.
Thanks, Mike P.
Mihael Pster, P.E direct. 781-721-4079 1 offc: 761-721-tG0 I rnpastri*,eiconsultaryt-co*m From: Srnzal, David S Frraiito:DSMALLl1enterlV.com]
Sent Thursday, January 23, 2014 2:52 PM To: Larnbe, Robett; Paster, Mike Cc: Mogolesko, F-ed Subject Pilgtim Station Bedrck Shear Wave Veocty Robert / Michael, As follow up to our telephone conference today, please see the attached documents:
a The first attachment is a draft of PNPS' request for rework of EPRI's GRMS analysis based on more refined shear wave velocity information found in plant records.
The second attachment contains excerpts from the PNPS Design & Analysis Report.that are relevant to the subject of bedrock shear wave velocity at the PNPS site (of particular interest are pages 3, 13, 25, 40 & 41 of the attachment).
As discussed, please provide your concurrence that it is reasonable to apply the originally specified shear wave velocity of 6000 fps to the upper weathered layer (6 ft) of bedrock and to apply a higher value to the underlying competent granodiorite, consistent with the original Dames & Moore site specific testing results presented in the Design.& Analysis Report.
Thank you again foryour timely support on this emergent issue, David S Small P.E.
Senior Lead Design Engineer Ptlgrm Nudlear Powf, Stabon Office: 508-830-7846 Cell: 603-498-7649 Page 3 of 3