BSEP 14-0087, Response to Request for Additional Information Associated with Near-Term Task Force Recommendation 2.1, Seismic Hazard and Screening Report

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

ML14241A432
Person / Time
Site:	Brunswick
Issue date:	08/14/2014
From:	Hamrick G Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BSEP 14-0087
Download: ML14241A432 (7)

Text

George T. Hamrick Vice President ENERGY, Brunswick Nuclear Plant P.O. Box 10429 Southport, NC 28461 o: 910.457.3698 10 CFR 50.54(f)

August 14, 2014 Serial: BSEP 14-0087 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Subject:

Brunswick Steam Electric Plant, Unit Nos. 1 and 2 Docket Nos. 50-325 and 50-324 Renewed License Nos. DPR-71 and DPR-62 Response to Request for Additional Information Associated with Near-Term Task Force Recommendation 2.1, Seismic Hazard and Screening Report

References:

1. NRC Letter, Request for Information Pursuantto 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-ichiAccident, dated March 12, 2012, ADAMS Accession No. ML12053A340.

2. Electric Power Research Institute (EPRI) Report 1025287, Seismic Evaluation Guidance, Screening, Prioritizationand Implementation Details (SPID)for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic, dated November 2012, ADAMS Accession No. ML12333A170.

3. NRC Letter, Endorsement of EPRI FinalDraft Report 1025287: "SeismicEvaluation Guidance,"dated February 15, 2013, ADAMS Accession No. ML12319A074.

4. Duke Energy Letter, Seismic Hazard and Screening Report (CEUS Sites), Response to NRC Request for Information Pursuantto 10 CFR 50.54(f) Regarding the Seismic Aspects of Recommendation 2. 1 of the Near-Term Task Force Review of Insights from the Fukushimd Dai-ichiAccident, dated March 31, 2014, ADAMS Accession No. ML14106A461.

5. NRC Letter, Brunswick Steam Electric Plant, Units 1 and 2 - Request for Additional Information Associated with Near-Term Task Force Recommendation 2. 1, Seismic Hazardand Screening Report, dated July 16, 2014, ADAMS Accession No. ML14195A071.

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U.S. Nuclear Regulatory Commission Page 2 of 3 Ladies and Gentlemen, On March 12, 2012, the U. S. Nuclear Regulatory Commission (NRC) staff issued a letter requesting information per Title 10 of the Code of Federal Regulations, Section 50.54(f)

(i.e., Reference 1). The letter requested licensees located in the Central and Eastern United States (CEUS) to submit a Seismic Hazard Evaluation and Screening Report. Reference 2 contains industry guidance and detailed information to be included in the Seismic Hazard Evaluation and Screening Report submittals. The industry guidance was endorsed by the NRC in Reference 3.

By letter dated March 31, 2014 (i.e., Reference 4), Duke Energy submitted to the NRC the Seismic Hazard and Screening Report. By letter dated July 16, 2014 (i.e., Reference 5), the NRC requested additional information related to the Individual Plant Examination for External Events (IPEEE) for Brunswick Steam Electric Plant (BSEP), Units 1 and 2. The NRC staff requested that a response be provided no later than August 15, 2014, as discussed during a recent phone call with members of my staff.

Enclosed, please find the response to the request for additional information.

This letter contains no new regulatory commitments.

If you have any questions regarding this submittal, please contact Mr. Lee Grzeck, Manager-Regulatory Affairs, at (910) 457-2487.

I declare under penalty of perjury that the foregoing is true and correct, executed on August 14, 2014.

Sincerely, C4~ a j~,mu George T. Hamrick RAZ/raz

Enclosure:

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

U.S. Nuclear Regulatory Commission Page 3 of 3 cc (with enclosures):

U. S. Nuclear Regulatory Commission, Region II ATTN: Mr. Victor M. McCree, Regional Administrator 245 Peachtree Center Ave, NE, Suite 1200 Atlanta, GA 30303-1257 U. S. Nuclear Regulatory Commission ATTN: Ms. Michelle P. Catts, NRC Senior Resident Inspector 8470 River Road Southport, NC 28461-8869 U. S. Nuclear Regulatory Commission ATTN: Mr. Andrew Hon (Mail Stop OWFN 8G9A) (Electronic Copy Only) 11555 Rockville Pike Rockville, MD 20852-2738 Chair - North Carolina Utilities Commission P.O. Box 29510 Raleigh, NC 27626-0510

BSEP 14-0087 Enclosure Page 1 of 4 Response to NRC Request for Additional Information (RAI) Associated With Near-Term Task Force Recommendation 2.1. Seismic Hazard and Screening Report

Background:

On March 12, 2012, the NRC issued a request for information pursuant to 10 CFR 50.54(f) to gather information concerning, in part, the seismic hazards at operating reactor sites and to enable the NRC staff to determine whether licenses should be modified, suspended, or revoked.

In response to the 50.54(f) letter, Duke Energy committed to follow the Electric Power Research Institute (EPRI) Report, "Seismic Evaluation Guidance: Screening, Prioritization and Implementation Details (SPID) for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic," (ADAMS Accession No. ML12333A170) as supplemented by the EPRI Report, "Seismic Evaluation Guidance: Augmented Approach for the Resolution of Fukushima Near-Term Task Force (NTTF) Recommendation 2.1: Seismic" (ADAMS Accession No. ML13102A142). The reevaluation of the seismic hazards for Brunswick Steam Electric Plant (BSEP), Units 1 and 2, was submitted to the NRC by letter dated March 31, 2014 (ADAMS Accession No. ML14106A461). On May 9, 2014, the NRC staff issued a letter (ADAMS Accession No. ML 14111 Al 47) identifying BSEP, Units 1 and 2, as "conditional screen-in" for the purposes of prioritizing and conducting additional evaluations.

In accordance with the SPID and Augmented Approach guidance, the reevaluated seismic hazard is used to determine if additional seismic risk evaluations are warranted. The SPID guidance provides criteria for a plant with ground motion response spectra (GMRS) above the safe shutdown earthquake, but bounded by the Individual Plant Examination for External Events (IPEEE) capacity spectrum. A plant screens out of conducting a seismic risk evaluation if the IPEEE capacity is greater than the GMRS in the 1-10 Hz range. The March 31, 2014, submittal demonstrates the adequacy of the IPEEE seismic evaluation and provides full-scope soil failure evaluation results.

By letter dated July 16, 2014 (ADAMS Accession No. ML14195A071), the NRC requested additional information related to the IPEEE for BSEP, Units 1 and 2. The NRC staff requested that a response be provided no later than August 15, 2014, as discussed during a recent phone call with BSEP staff.

NRC RAI 1:

In Appendix B, Section 2.1.2 of the submittal, it states that soils evaluation considered relevant structures on the Safe Shutdown Equipment List which includes the intake canal. The submittal also states that slope stability screens out at BSEP. Describe the basis for screening out slope stability along the intake canal under the review level earthquake loading.

BSEP 14-0087 Enclosure Page 2 of 4 BSEP Response to RAI 1:

The Intake Canal was originally designed to provide normal cooling water loads for five (5) units.

The current design accommodates a flow requirement of 1390 cubic feet (ft3 )/ second per unit.

The maximum designed capacity of the Intake Canal is approximately 7,000 ft3/second. The Intake Canal mean sea level (MSL) velocity for one unit operating is 0.3 feet (ft)/second, and maximum low tide velocity is 0.4 ft/second. When two units are in operation the MSL velocity is 0.6 ft/second, and maximum low tide velocity is 0.8 ft/second. The representative low water level velocity in the Intake Canal is 1.5 ft/second.

The bottom of the Intake Canal is at Elevation -18 feet MSL; The Intake Canal bottom is 170 feet wide, and the side slopes are at a 4Horizontal (H):1 Vertical (V) slope in the marsh area, and 3H:1V in the high ground area. The total length of the Intake Canal is 2.57 miles. The figure below provides a cross-sectional profile of the Intake Canal.

High Ground Area Intake Canal Cross-Section Profile UINTAKE CANAL

..SERVICE ROAD

.SERVICE ROAD EL. 36' I

The original Intake Canal design evaluation acknowledges that the Intake Canal is susceptible to slope sliding as discussed in the original Final Safety Analysis Report (FSAR). Section 2.4.8.2 of the current Updated FSAR provides a general description of the Intake Canal.

A breakdown of the consequences of liquefaction based on soil conditions and topography is provided in EPRI Report NP-6041-SL, Table 7-1A, "Relationship Between Observed Lateral Deformation During Earthquakes and Geometric Properties of Liquefied Alluvial Soils". Intake

BSEP 14-0087 Enclosure Page 3 of 4 Canal slope slides similar to those presented in Table 7-1A will occur based on the canal design slope, elevation changes and susceptibility to liquefaction.

To illustrate the margin associated with the Intake Canal, sliding at any point along the Intake Canal length, on both sides, is conservatively postulated to occur. For the purpose of determining the adequacy of the IPEEE for BSEP, Units 1 and 2, complete failure of canal slopes with all soils sliding into canal is assumed. This results in a median angle of repose of approximately 50 corresponding to a slope of approximately 12H:1V. The amount of material transported will not significantly impact the Intake Canal performance.

The Service Water system provides all critical cooling water needs for normal and emergency plant conditions. Service Water pump capacity for all ten (10) pumps for both units is 80,000 gallons per minute (gpm). At a velocity of 1.5 ft/second, the required cross-section area for 80,000 gpm is 119 square feet (ft2). Design cross-section area of the canal at low tide is 3,760 ft 2. After postulated worst case canal slope failure the remaining cross-section area of water would be at least 910 ft2 . This is more than seven times the maximum demand of all 10 Service Water pumps. For this worst case scenario, the Intake Canal design capacity ensures significant margin remains to provide adequate cooling water to both units following a Review Level Earthquake (RLE) of 0.3g.

Simplistic & Conservative Intake Canal Profile After Slope Failure EL 0' E .-- , .

2 I \-A=910 Ft A monitoring program is in place to perform hydrographic surveys of cross-sections along the length of the Intake Canal at various stations and is used to determine when canal dredging is required to maintain the Intake Canal profile. Intake Canal maintenance dredging is performed in accordance with a recurring Preventive Maintenance (PM) program Work Order model. Post dredging hydrographic surveys are performed to ensure acceptable Intake Canal profiles are achieved.

BSEP 14-0087 Enclosure Page 4 of 4 NRC RAI 2:

In Appendix B, Section 2.1.2 of the submittal, it states that considerations similar to Table 7-1A of Reference 6.4 was used for screening out liquefaction for the intake canal. If appears that the reference should have been Reference 6.6. Clarify whether the submittal should cite Reference 6.6 instead of Reference 6.4 when referring to Table 7-1A or provide a description of the considerations were used for screening.

BSEP Response to RAI 2:

The submittal should have cited Reference 6.6 instead of Reference 6.4 when referring to Table 7-1A.