L-14-385, Response to Request for Additional Information Associated with Near-Term Task Force (NTTF) Recommendation 2.1, Seismic Hazard and Screening Report

Response to Request for Additional Information Associated with Near-Term Task Force (NTTF) Recommendation 2.1, Seismic Hazard and Screening Report

ML14335A482
Person / Time
Site:	Beaver Valley
Issue date:	12/01/2014
From:	Emily Larson FirstEnergy Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-14-385, TAC MF3726, TAC MF3727
Download: ML14335A482 (5)

Text

FENOC' Beaver Valley Power Station P.O. Box4 Shippingport, PA 15077 FirstEnergy Nuclear Operating Company Eric A. Larson 724-682-5234 Site Vice President Fax: 724-643-8069 December 1, 2014 L-14-385 10 CFR 50.54(f)

ATTN: Document Control Desk U.S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852

.SUBJE;CT:

Beaver Valley Power Station, Unit Nos. 1 and 2 Docket No. 50-334, License No. DPR-66 Docket No. 50-412, License No. NPF-73 Response to Request for Additional Information Associated with Near-Term Task Force (NTTF) Recommendation 2.1, Seismic Hazard and Screening Report (TAC Nos.

MF3726 and MF3727)

On March 12, 2012, the Nuclear Regulatory Commission (NRC) issued a letter titled, "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," to all power reactor licensees and holders of construction permits in active or deferred status. Enclosure 1 of the 10 CFR 50.54(f) letter addresses NTTF Recommendation 2.1 for seismic. By letter dated March 31, 2014, FirstEnergy Nuclear Operating Company (FENOC) submitted NTTF Recommendation 2.1 seismic hazard and screening reports for Beaver Valley Power Station (BVPS) Unit No. 1 and BVPS Unit No. 2 in response to the 10 CFR 50.54(f) request.

By letter dated October 31, 2014, the NRC staff requested additional information to complete its review of the reports. The response to this request for additional information is attached.

Beaver Valley Power Station, Unit Nos. 1 and 2 L-14-385 Page 2 There are no new regulatory commitments contained in this letter. If there are any questions or if additional information is required, please contact Mr. Thomas A. Lentz, Manager - Fleet Licensing, at 330-315-6810.

I declare under penalty of perjury that the foregoing is true and correct. Executed on December _J_, 2014.

Sincerely, Eric A. Larson

Attachment:

Response to Request for Additional Information cc: Director, Office of Nuclear Reactor Regulation (NRR)

NRC Region I Administrator NRC Resident Inspector NRR Project Manager Director BRP/DEP (w/o Attachment)

Site BRP/DEP Representative (w/o Attachment)

Attachment L-14-385 Response to Request for Additional Information Page 1 of 3 By letter dated March 31, 2014, FirstEnergy Nuclear Operating Company (FENOC) submitted Near-Term Task Force (NTTF) Recommendation 2.1 seismic hazard and screening reports for Beaver Valley Power Station (BVPS) Unit No. 1 and BVPS Unit No. 2 in response to the March 12, 2012 Nuclear Regulatory Commission (NRC) request pursuant to 10 CFR 50.54(f). By letter dated October 31, 2014, the NRC staff requested additional information to complete its review of the reports. The response to this request for additional information (RAI) is provided below. The NRC request is provided in bold type, followed by the FENOC response.

RAI: Review of geophysical properties used in the site response analysis Section 2.3.2.3 of the NTTF Recommendation 2.1 Seismic Hazard and Screening Report for Beaver Valley states that the total kappa values for each of the three profiles was determined using the Central Eastern United States (CELIS) rock site equation for which the shear wave velocity (Vs) over the upper 100 feet [ft] of the profile (Vs100) is the input variable. Assuming Vs100 to be 5000 ft/sec for Profile P1, 4348 ft/second (sec) for Profile P2, and 5750 ft/sec for Profile P3, results in total kappa values of 15 millisecond (msec) for P1, 18 msec for P2, and 13 msec for P3 were obtained, respectively. The CELIS rock site equation for kappa includes the assumed kappa value of 6 msec from the underlying reference rock.

The NRC Staff has reviewed the information submitted and has determined that the following additional information is needed to complete its review.

Consistent with the 50.54(f) letter and the SPID guidance [The screening, prioritization, and implementation details (SPID) can be found under ADAMS Accession No. ML12333A170], please provide the basis for total kappa values of 21.3 msec for P1, 23.7 msec for P2, and 19.3 msec for P3 calculated for the Beaver Valley Power Station.

Response

The kappa values estimated for the Beaver Valley probabilistic seismic hazard analysis (PSHA) used for the seismic probabilistic risk assessment (SPRA) have been revised relative to the kappa values listed in the March submittal to the NRC. The revised ground motion response spectra (GMRS) are being used in the Beaver Valley Power Station SPRA as well as the Expedited Seismic Evaluation Process (ESEP) Report.

Consistent with our interpretation of the SPID guidelines, the March submittal assumed that the CEUS rock site equation for kappa did not include the assumed kappa value of 6 msec from the underlying reference rock. This interpretation was reached based on the example provided in Section B-5.1.3.1 of the SPID, where the Vs(100) value of 5,000 ft/sec is stated to result in a total kappa value of about 20 msec, comprising 14 msec from the sedimentary rock and 6 msec from the underlying reference rock.

Attachment L-14-385 Page 2 of 3 The updated calculation of seismic hazard and the GMRS for use in the SPRA reflects that, based on examination of the source reference, the SPID equation does include the assumed kappa value of 6 msec from the underlying reference rock. This update does not alter the Seismic Hazard and Screening Report (SHSR) conclusion. The updated GMRS is being used for the SPRA as well as the ESEP in lieu of the GMRS presented in the March 2014 submittal.

In addition to revised kappa values, the updated PSHA/GMRS calculation completed for the SPRA also includes two other modifications:

• The response spectra for the SPRA are the foundation input response spectra (FIRS) for each of the building locations. Because FIRS are provided, the soil column was extended from the reactor building elevation (EL) of 680.9 ft to plant grade at EL 735 ft. The FIRS were estimated accounting for the full soil column and the appropriate truncated soil column for the appropriate foundation elevation for each building, consistent with guidance from NRG (DC/COL-ISG-17, Ensuring Hazard-Consistent Seismic Input for Site Response and Soil Structure Interaction Analyses, March 2010).

• The site response analysis for the SPRA PSHA incorporated modified damping values for the top 500 ft of the Paleozoic rock section. In the March submittal, for the non-linear portion of the analysis, Electric Power Research Institute (EPRI) rock damping values were used for all depths in the top 500 ft. In the SPRA PSHA, the EPRI rock damping values were limited to the top 100 ft of the Paleozoic rock section, and damping values from Stakoe et al., (2003) were used between 100 and 500 ft of the Paleozoic rock section.

• Kappa values for each of the site profiles were revised (relative to the March submittal) as follows - for Profile P1 the kappa value is 16.7 msec, for Profile P2 kappa values are 19.1 and 28.6 msec, and for Profile P3 the kappa values are 14.0 and 9.7 msec. These values represent epistemic uncertainty in kappa for the Beaver Valley site.

As a result of these changes, the FIRS for the Reactor Building increased relative to the GMRS provided in the March submittal. Figure 1, which compares the SPRA GMRS to the GMRS included in the March 2014 submittal illustrates this increase.

Attachment L-14-385 Page 3 of 3 1.0 - - - - - - - - - - - - - - - - - - - -

Damping= 5%

0.8 ----------+-------------

~ 0.6 -+--------+---~COllior--*+=--

nl

~ 0.4 +-----------+---

QI a.

Ill

0. 10 1.00 10.00 100.00 Freq uency (Hz)

- SPRA GMRS - GMRS, March 2014 Submitta l FIGURE 1 COlVIPARISON OF SPRA GMRS AND GMRS IN MARCH SUBMITTAL

Reference:

Stokoe, K. H., W. K. Choi, and F-Y Menq, 2003, "Summary Report: Dynamic Laboratory Tests: Unweathered and Weathered Shale Proposed Site of Building 9720-82 Y-12 National Security Complex, Oak Ridge, Tennessee," Department of Civil Engineering, The University of Texas at Austin, Austin, Texas, 2003.