ML14246A428

Screening and Prioritization Results Regarding Seismic Hazard Reevaluations for Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-Ichi Accident Based on Individual Plant Examination of External Events

ML14246A428
Person / Time
Site:	Millstone, Arkansas Nuclear, FitzPatrick
Issue date:	11/21/2014
From:	Bill Dean Office of Nuclear Reactor Regulation
To:	Dominion Nuclear Connecticut, Entergy Nuclear Operations, Entergy Operations
Balazik M, NRR/JLD, 415-2856
References
TAC MF3718, TAC MF3822, TAC MF3823, TAC MF3968
Download: ML14246A428 (7)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 November 21, 2014 The Operating Power Reactor Licensees on the Enclosed List

SUBJECT:

SCREENING AND PRIORITIZATION RESULTS REGARDING SEISMIC HAZARD REEVALUTIONS FOR RECOMMENDATION 2.1 OF THE NEAR-TERM TASK FORCE REVIEW OF INSIGHTS FROM THE FUKUSHIMA DAI-ICHI ACCIDENT BASED ON INDIVIDUAL PLANT EXAMINATION OF EXTERNAL EVENTS EVALUATION (TAC NOS. MF3968, MF3822, MF3823, AND MF3718)

The purpose of this letter is to transmit the U.S. Nuclear Regulatory Commission (NRC) staff's final screening and prioritization determination (Enclosure 1) to licensees (Enclosure 2) based on information provided in public meetings, responses received to specific requests for additional information (RAI), and audits. It does not convey the staff's final determination regarding the adequacy of the calculated hazard. The NRC staff is continuing 1ts review of the submitted seismic hazard reevaluation, and may request additional information to support this review. The NRC staff plans to issue a staff assessment on the reevaluated seismic hazard no later than the third quarter 2015.

BACKGROUND On March 12, 2012, the NRC issued a request for information pursuant to Title 10 of the Code of Federal Regulations (1 0 CFR), Part 50, Section 50.54(f) (hereafter referred to as the 50.54(f) letter) (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12053A340). The purpose of that request was to gather information concerning, in part, seismic hazards at each operating reactor plant and to enable the NRC staff to determine whether licenses should be modified, suspended, or revoked. Further, the 50.54(f) letter stated that the NRC would provide screening and prioritization results and would also indicate deadlines, if necessary, for individual plants to complete seismic risk evaluations that assess the total plant response to the reevaluated seismic hazard. In response to the 50.54(f) letter, all addressees committed to follow the Electric Power Research Institute Report (EPRI), "Seismic Evaluation Guidance: Screening, Prioritization and Implementation Details (SPID) for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic," 1 as supplemented by the EPRI Report, "Seismic Evaluation Guidance: Augmented Approach for the Resolution of Fukushima Near Term Task Force Recommendation 2.1: Seismic" 2 (referred to as the expedited approach).

1 The SPID guidance document can be found in ADAMS under Accession No. ML12333A170. The staff endorsement letter for the SPID guidance can be found in ADAMS under Accession No. ML12319A074.

2 The expedited approach guidance document can be found in ADAMS under Accession No. ML13102A142.

In response to the 50.54(f) letter, licensees submitted their reevaluated seismic hazard in March 2014. During the NRC's screening and prioritization 30-day review, the staff identified several plants that a determination could not be made and interactions with the licensee were needed to reach resolution. The staff designated several plants as conditionally screened-in because additional information was needed to verify the adequacy of the Individual Plant Examination for External Events (IPEEE) results for screening purposes. Subsequently, by letter dated May 9, 2014 (ADAMS Accession No. ML14111A147), the NRC staff informed all licensees of operating reactors in the central and eastern United States of the screening and prioritization results to support completing seismic risk and limited-scope evaluations, as described in Enclosure 1 of the 50.54(f) letter.

SCREENING AND PRIORTIZATION PROCESS As discussed in the May 9, 2014 letter, the NRC staff's screening review was performed using the SPID guidance. The SPID provides guidance on seismic screening when the ground motion response spectra (GMRS) is above the safe shutdown earthquake (SSE), but bounded by the IPEEE capacity spectrum. To use the IPEEE capacity spectrum for seismic screening, licensees needed to demonstrate the IPEEE adequacy by satisfying specific criteria in the SPID.

If the IPEEE capacity is greater than the GMRS in the 1-10 Hertz (Hz) range and meets the IPEEE-related screening criteria in the SPID, a plant screens out of conducting a seismic risk evaluation.

The NRC grouped the "screened in" plants into three groups that reflects certain key parameters such as (1) the maximum ratio of the new re-evaluated hazard (GMRS) to the SSE in the 1-10 Hz range; (2) the maximum ground motion in the 1-10 Hz range; and (3) insights from previous seismic risk evaluations. Group 1 plants are generally those that have the highest re-evaluated hazard relative to the original plant seismic design basis (GMRS to SSE) as well as ground motions in the 1-10 Hz range that are generally higher in absolute magnitude. The plants screened into Group 2 have an increase in seismic hazard and new ground motion estimate that are smaller than Group 1 plants. Group 3 plants have GMRS to SSE ratios that are greater than 1, but the amount of exceedance in the 1-10 Hz range is relatively small, and the maximum ground motion in the 1-10 Hz range is also not high.

SCREENING AND PRIORTIZATION REVIEW ASSESSMENT Several public meetings were held in June and July of 2014 between the NRC staff and licensees, in part, to address the staff's questions regarding adequacy of a plant's IPEEE evaluation to demonstrate plant seismic capacity. By letters3 dated July 16, 2014, the NRC staff issued RAis to Arkansas Nuclear One, Units 1 and 2, and Millstone Power Station, Unit 2, to support the NRC's final screening and prioritization determination. Based on the staff's review of information provided in the licensees' RAI response 4 and audit5 , the staff was able to make final screening determinations. For Arkansas Nuclear One, Units 1 and 2, and Millstone Power 3

The letters can be found in ADAMS under Accession Nos. ML14195A059 and ML14195A034, respectively for Arkansas Nuclear One and Millstone Power Station.

4 The RAI responses can be found in ADAMS under Accession Nos. ML14233A275 and ML14204A620, respectively for Arkansas Nuclear One and Millstone Power Station.

5 An audit was conducted for Millstone Power Station, Unit, 2 on October 23, 2014. The audit plan can be found in ADAMS under Accession No. ML14295A085.

Station, Unit 2, the NRC staff verified that their IPEEE evaluation is adequate for seismic screening purposes in accordance with the SPID criteria and guidance. Enclosure 1 provides the staff's final screening and prioritization determination and identifies the limited-scope evaluations to be completed. The spent fuel pool evaluation will be performed because spent fuel pools were not included in the original scope of the IPEEE evaluation. The high frequency evaluation will be performed because the GMRS exceeds the IPEEE high confidence of low probability of failure spectrum in the greater than 10 Hz range.

In the May 9, 2014, letter, the NRC screened-in Indian Point Nuclear Generating, Unit 2 and 3 (Indian Point), into priority Group 1 to perform a seismic risk evaluation, expedited approach, high frequency evaluation, and spent fuel pool evaluation. On June 19, 2014, the NRC staff held a public meeting 6 with Entergy to discuss issues resulting from the seismic screening and prioritization for several Entergy facilities. By letters 7 dated August 18, 2014, and November 5, 2014, the NRC received a request from Entergy Nuclear Operations, Inc. (Entergy) to reprioritize Indian Point, Unit 3, to a lower priority grouping (Group 2 or 3) for seismic risk evaluations. The NRC considered the information in the request letters and confirms that Indian Point, Unit 3, remains a priority Group 1 plant. The August 2014 letter refers to a number of plant enhancements completed since the IPEEE and Generic lssue-199 review activities.

Entergy indicates that these enhancements have improved plant safety and provides some assurance that Indian Point, Unit 3, can cope with the reevaluated seismic hazard while the expedited approach and risk evaluations are conducted. The November 2014 letter refers to resource hardships associated with performing a seismic risk evaluation for both Indian Point Units 2 and 3 simultaneously.

NRC affirms that Indian Point, Unit 3 remains in priority Group 1 because (1) the Indian Point reevaluated seismic hazard magnitude and ratio to SSE is consistent with other priority Group 1 plants; (2) the changes to Indian Point, Unit 3, have not been reflected in the seismic probabilistic risk assessment that was developed for the IPEEE review; (3) the seismic risk review contained in letter8 dated June 26, 2013, does not meet SPID Section 3.3 criteria for demonstrating IPEEE quality or acceptability of the plant seismic capacity; and (4) the request did not sufficiently demonstrate resource or schedule constraints to be reprioritized to either Group 2 or 3. Group 1 plants are expected to conduct and submit to the NRC their seismic expedited approach by December 31, 2014, and their seismic risk evaluation by June 30, 2017.

6 A summary of the public meeting can be found in ADAMS under Accession No. ML14197A583.

7 The letters can be found in ADAMS under Accession Nos. ML14241A026 and ML14310A666, respectively.

8 The letter and seismic reassessment can be found in ADAMS under Accession Nos. ML13183A279 and ML13183A280, respectively.

If you have any questions on this matter, please contact Michael F. Balazik, Japan Lessons-Learned Division Project Manager at (301) 415-2856 or at Michaei.Balazik@nrc.gov.

Enclosures:

1. Seismic Screening and Prioritization Final Results

2. List of Addressees cc: Listserv

Seismic Screening and Prioritization Final Results Limited-scope Evaluations Seismic Risk High Low Spent Fuel Expedited Screening Evaluation Frequency Frequency Pool Plant Name Approach Result (Prioritization Evaluation Evaluation Evaluation Evaluation Group)

Arkansas Nuclear One, Units 1 Out X X and 2 Indian Point Nuclear In X 1 X X Generating, Unit Nos. 2 and 3 Millstone Power Station, Unit 2 Out X X Enclosure 1

List of Addressees Arkansas Nuclear One Entergy Operations, Inc.

Docket Nos. 50-313 and 50-368 License Nos. DPR-51 and NPF-6 Vice President, Operations Arkansas Nuclear One Entergy Operations, Inc.

1448 S.R. 333 Russellville, AR 72802 Indian Point Nuclear Generating Entergy Nuclear Operations, Inc.

Docket Nos. 50-247 and 50-286 License Nos. DPR-26 and DPR-64 Vice President, Operations Entergy Nuclear Operations, Inc.

Indian Point Energy Center 450 Broadway, GSB P.O. Box 249 Buchanan, NY 10511-0249 Millstone Power Station Dominion Nuclear Connecticut, Inc.

Docket No. 50-336 License No. DPR-65 Mr. David A. Heacock President and Chief Nuclear Officer Dominion Nuclear Connecticut, Inc.

lnnsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060 Enclosure 2

ML14246A428 *via e-mail OFFICE NRR/JLD/JHMB/PM NRR/JLD/LA NRO/DSENRGS2/BC NRR/JLD/JHMB/BC NAME MBalazik Slent DJackson SWhaley DATE 10/ /14 10/27/14 10/28/14 10/28/14 OFFICE NRR/DORL/LPL 1-1/PM* OGC* NRR/JLD/D NRR/D NAME DPickett BHarris JDavis WDean DATE 11/17/14 10/30/14 11/07/14 11/21/14