ML17202U682

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Staff Review of Mitigating Strategies Assessment Report of the Impact of the Reevaluated Seismic Hazard Developed in Response to the March 12, 2012, 50.54(F) Letter
ML17202U682
Person / Time
Site: Millstone  Dominion icon.png
Issue date: 08/24/2017
From: Steve Wyman
Japan Lessons-Learned Division
To: Stoddard D
Dominion Nuclear Connecticut
Wyman S, NRR/JLD, 415-3041
References
Download: ML17202U682 (16)
v • d • e


Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. Daniel G. Stoddard Senior Vice President and Chief Nuclear Officer Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711 August 24, 2017

SUBJECT:

MILLSTONE NUCLEAR POWER STATION , UNITS 2 AND 3 -STAFF REVIEW OF MITIGATING STRATEGIES ASSESSMENT REPORT OF THE IMPACT OF THE REEVALUATED SEISMIC HAZARD DEVELOPED IN RESPONSE TO THE MARCH 12, 2012, 50.54(f) LETTER

Dear Mr. Stoddard:

The purpose of this letter is to provide the U.S. Nuclear Regulatory Commission's (NRG) assessment of the seismic hazard mitigating strategies assessment (MSA), as described in the April 27, 2017, letter (Agencywide Documents Access and Management System (ADAMS) Accession No. ML17123A378), submitted by Dominion Nuclear Connecticut, Inc. (Dominion , the licensee) for Millstone Nuclear Power Station, Units 2 and 3 (Millstone).

The NRG staff evaluated the Millstone strategies developed under Order EA-12-049 and described in Millstone's Final Integrated Plans (FIPs) for Unit 2 (ADAMS Accession No. ML16005A184) and Unit 3 (ADAMS Accession No. ML15182A012).

The staff's review of Millstone's mitigating strategies for Units 2 and 3 was documented in a safety evaluation dated July 1, 2016 (ADAMS Accession No. ML16099A171 ). The purpose of the safety evaluation is to ensure that the licensee has developed guidance and proposed designs which , if implemented appropriately , should adequately address the requirements of Order EA-12-049.

An inspection confirmed compliance with the order and is documented in a report dated November 28, 2016 (ADAMS Accession No. ML16334A454).

The following NRG staff review confirms that the licensee has adequately addressed the reevaluated seismic hazard within Millstone's mitigation strategies for beyond-design-basis external events. BACKGROUND By letter dated March 12, 2012 (ADAMS Accession No. ML12053A340), the NRG issued a request for information pursuant to Title 10 of the Code of Federal Regulations (1 O CFR), Section 50.54(f) (hereafter referred to as the 50.54(f) letter). The 50.54(f) letter was issued as part of implementing lessons-learned from the accident at the Fukushima Dai-ichi nuclear power plant. Enclosure 1 to the 50.54(f) letter requested that licensees reevaluate the seismic hazard using present-day methodologies and guidance. Concurrent with the reevaluation of seismic hazards , the NRG issued Order EA-12-049 , "Issuance of Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events" (ADAMS Accession No. ML12054A736).

The order requires holders of operating power reactor licenses a nd construction permits issued under 1 O CFR Part 50 to develop, implement, and maintain guidance and strategies to maintain or restore core cooling , containment , and spent fuel pool cooling following a beyond-design-basis external event.

D. Stoddard On December 10, 2015 (ADAMS Accession No. ML16005A621

), the Nuclear Energy Institute (NEI) submitted Revision 2 to NEI 12-06, including guidance for conducting MSAs using the reevaluated hazard information.

The NRG subsequently endorsed NEI 12-06, Revision 2, with exceptions, clarifications, and additions, in Japan Lessons-Learned Division (JLD) interim staff guidance (ISG) JLD-ISG-2012-01, Revision 1, "Compliance with Order EA-12-049, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Basis External Events" (ADAMS Accession No. ML15357A163). MITIGATION STRATEGIES ASSESSMENT By letters dated December 15, 2015, and March 15, 2016 (ADAMS Accession Nos. ML15328A268 and ML16057A785, respectively), the NRG staff documented its review of the licensee's reevaluated seismic hazard, also referred to as the mitigation strategies seismic hazard information (MSSHI). The staff found that the Millstone Ground Motion Response Spectrum (GMRS) exceeds the safe shutdown earthquake (SSE) in the 1 to 1 O Hertz (Hz) range. However, based on the NRG staff's comparison of the GMRS to the SSE and the review of additional hazard and risk information, the NRG staff concluded that a seismic risk evaluation was not merited for Millstone.

But because the GMRS exceeds the SSE above 1 O Hz, a high frequency (HF) confirmation is merited. In addition, the staff concluded that the GMRS determined by the licensee adequately characterizes the reevaluated seismic hazard for the Millstone site. By letter dated December 22, 2016 (ADAMS Accession No. ML16365A036), Dominion submitted a HF Confirmation report for Millstone, Units 2 and 3. By letter dated February 13, 2017 (ADAMS Accession No. ML17038A035), the NRG staff concluded, based on its review , that the licensee correctly implemented the guidance in conducting the HF confirmation for Millstone.

All evaluated components demonstrated adequate seismic capacity and no component modifications were required.

By letter dated April 27, 2017 (ADAMS Accession No. ML17123A378), Dominion submitted a MSA Report for Millstone. The licensee stated that the Millstone MSA was performed consistent with Appendix H of NEI 12-06, Revision 4, which describes acceptable methods for demonstrating that the reevaluated seismic hazard is addressed within the Millstone mitigation strategies for beyond-design-basis external events. NEI 12-06, Revision 4 has not been officially endorsed at the time of this review. However , the NRG staff confirmed that the licensee's seismic hazard MSA is consistent with the guidance in Section H.4.4 of NEI 12-06 , Revision 2 , as endorsed by JLD-ISG-2012-01, Revision 1. Therefore, the methodology used by the licensee is acceptable to perform an assessment of the mitigation strategies that addresses the reevaluated seismic hazard. The NRG staff performed checklist reviews of the seismic hazard MSA for Millstone Units 2 and 3. The checklists are provided as attachments to this letter. The NRG staff identified one deviation from guidance, but found that Dominion met the intent of the guidance. The staff did not identify any deficiencies.

All evaluated components demonstrated adequate seismic capacity and no component modifications were required.

The NRG staff completed its review of the seismic hazard MSA for Millstone and concluded that sufficient information has been provided to demonstrate that the licensee's plans for the development and implementation of guidance and strategies under Order EA-12-049 appropriately address the reevaluated seismic hazard information stemming from the 50.54(f) letter.

D. Stoddard If you have any questions , please contact me at (301) 415-3041 or via e-mail at Stephen.Wyman@nrc.gov. Docket Nos. 50-336 and 50-423

Enclosure:

Technical Review Checklist cc w/encl: Distribution via Listserv y an, Project Manager nagement Branch Japan L essons-Learned Division Office of Nuclear Reactor Regulation TECHNICAL REVIEW CHECKLIST BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO PATH FOUR MITIGATING STRATEGY ASSESSMENT MILLSTONE NUCLEAR POWER STATION, UNIT 2 DOCKET NO. 50-336 The NRC staff performed the following checklist review based on Attachment I of the April 27, 2017, letter for Millstone, Unit 2. Deviations, deficiencies, and conclusions are noted at the end of each section and an overall conclusion is provided at the end of the checklist.

I. Background and Assessment to Mitigation Strategies Seismic Hazard Assessment (MSSHI) This section establishes basic background and assessment to MSSHI criteria in Nuclear Energy Institute (NEI) 12-06, Appendix H. Licensee approach to mitigating strategies assessment (MSA): Was the MSA conducted in accordance with NEI 12-06, Revision 2 ¥es/ No as endorsed by the staff? Was the MSA conducted using an alternate method? Status of Order EA-12-049 Flexible Mitigation Strategy at the time of this review: Yes-/ Ne Has the licensee submitted a Final Integrated Plan? Yes; Ne Has the NRC staff completed a safety evaluation for the mitigation Yes; Ne strategy?

Has the NRC staff confirmed compliance with Order EA-12-049 by Yes / Ne successfully completing the temporary instruction (Tl}-191 inspection?

Status of MSSHI Did the licensee use the Ground Motion Response Spectra (GMRS) and Uniform Hazard response Spectra (UHRS) as submitted in response to the 50.54(f) request for information and reviewed by the NRC staff? Yes I Ne Enclosure Has the plant equipment relied on for FLEX strategies previously been evaluated as seismically robust to the plant safe shutdown earthquake (SSE) levels? Is the maximum ratio of GMRS/SSE in the range of 1-10 Hertz (Hz) less than 2? Did the licensee meet the seismic evaluation criteria described in NEI 12-06, Section H.5? Yes I No I Nl\ Yes I Ne Yes /-Ne Notes from staff reviewer:

The GMRS/SSE ratio is 1.345. This meets the criteria of NEI 12-06, H.5. Deviation(s) or deficiency (ies) and Resolution:

The licensee performed this MSA using NEI 12-06, Revision 4, but as of the date of performance of the MSA, only Revision 2 has been endorsed by the NRC staff. The NRC staff has determined that working to Revision 4 is acceptable because there are no substantive differences between the two revisions in the portions that are used for the MSA. Consequence(s)

None The NRC staff concludes:
  • The licensee meets the background and assessment to MSSHI criteria in NEI 12-06, Appendix H. II. Expedited Seismic Evaluation Process (ESEP) Equipment Equipment used in support of the FLEX strategies has been evaluated to demonstrate seismic adequacy following the guidance in Section 5 of NEI 12-06. As stated in Appendix H of NEI 12-06, previous seismic evaluations should be credited to the extent that they apply for the assessment of the MSSHI, including the ESEP evaluations performed in accordance with Electric Power Research Institute (EPRI) 3002000704.

Licensees may reference a previous ESEP submittal , submit a new or updated ESEP report, or provide other adequate justification or evaluation.

Did the licensee previously perform an ESEP? Did the licensee provide a new or updated ESEP report with the MSA? Yes I Ne ¥es/ No ¥es/ No If the licensee did not perform ESEP, did they provide adequate justification that the expedited seismic equipment list (ESEL) structures , systems , and components (SSCs) are acceptable in accordance with the original guidance and in accordance with NEI 12-06 Section H.5 C 10% capacity criteria?

If the licensee did not perform the ESEP , did they perform an evaluation consistent with the guidance in NEI 12-06, Section H.4.4, Steps 2 and 3 , including the evaluation of FLEX components that were not previously evaluated to GMRS or 2 times the SSE? Yes I No I Nl\ Yes /-Ne /-NA Notes from staff reviewer: Millstone did not perform ESEP as a stand-alone evaluation , but did provide an equipment list and evaluated ESEP scope of equipment consistent with the MSA guidance.

The NRC staff reviewed the equipment list in Dominion document number R2730-003-001

-2. Deviation(s) or deficiency(ies) and Resolution:

None Consequence(s)

None The NRC staff concludes:
  • The licensee has evaluated seismic adequacy of equipment used in support of FLEX strategy consistent with the NEI 12-06 , Appendix H guidance.

Ill Inherently I Sufficiently Equipment Appendix H , Section 4.4 of NEI 12-06 , Revision 2 documents the process and justification for inherently and sufficiently rugged SSCs. The licensee:

Documented the inherently and sufficiently rugged SSCs consistent with the NEI 12-06 Appendix H guidance. Yes I Ne Yes I Ne Notes from staff reviewer:

Inherently rugged items are documented in Section 2.3 of the Millstone MSA report. Deviation(s) or deficiency(ies) and Resolution:

None Consequence(s)

None The NRC staff concludes:
  • The licensee's assessment of inherently and sufficiently rugged SSCs met the intent of the NEI 12-06, Appendix H guidance.

IV Evaluation of Components Not Covered bv ESEP ESEP specifically excluded the evaluation of certain components of the FLEX strategy in an effort to provide stakeholders with near-term confidence in a plant's seismic capacity. However, licensees will be required to complete those evaluations as part of the Path 4 MSA to demonstrate compliance with the impending rule. Were the following components , not evaluated in the ESEP , evaluated as part of the MSA?:

  • FLEX Storage Building
  • Non-seismic CAT I structures
  • Operator Pathways credited in FLEX strategy
  • Tie down of FLEX portable equipment
  • Seismic interactions o Masonry block wall o Piping attached to tanks o Flooding from non-seismically robust tanks o Distributed systems (Piping/conduit/raceways/cable trays) o Other potential areas of interaction
  • FLEX equipment haul paths
  • Other equipment (list in Staff Reviewer Notes) Did the licens ee provide adequate description/docum e ntatfon of the evaluation?

Yes I Ne Yes I Ne Yes I Nol NA Yes I Ne Yes I Ne Yes I Ne Yes I Ne Yes I Ne Yes I Ne Yes I Ne Yes I Ne ¥-es-/ No I-NA Yes I Ne Notes from staff reviewer:

The staff reviewed liquefaction potential evaluations for the FLEX building and FL E X equipment h a ul paths in Dom i nion calculations C E-2017 , R e vision O a nd C E-2 027 , Revi s ion 0. The NRC s t a ff found that pot e nti a l deform a tion s to haul paths or the FLEX building would not prevent FLEX deployment. Deviation(s) or deficiency(ies) and Resolution:

None Consequence(s):

None The NRC staff concludes:

  • The licensee followed the NEI 12-06, Appendix H guidance in evaluating SSCs not deemed inherently rugged. V. Spent Fuel Pool (SFP) Coolinq Per NEI 12-06, Appendix H, Section 4.4 , licensees need to evaluate the adequacy of SFP cooling equipment to the GMRS. Most plants include the Order EA-12-051 SFP Level Instrument as part of the strategy.

The licensee:

  • Clearly identified the SSCs and locations of the equipment that is part of the final FLEX SFP cooling strategy.
  • Clearly stated the seismic design basis (e.g. SSE) of the equipment used in the strategy.
  • Provided adequate description or documentation of the SFP cooling equipment's evaluation to the GMRS. Portable equipment and flexible hoses do not need to be evaluated.

Notes from staff reviewer:

None Deviation(s) or deficiency(ies) and Resolution:

None Consequence(s)

None The NRC staff concludes:
  • The licensee followed the NEI 12-06, Appendix H guidance in evaluating SFP cooling. VI. High Frequency (HF) Per NEI 12-06, Appendix H, Section 4.4, licensees with GMRS exceedance of the SSE above 1 O Hz need to evaluate bi-stable components such as relays using the methodology described in NEI 12-06, Section H.4.2. The HF evaluation may have been submitted under separate letter or may be sent as an attachment to the MSA Yes I Ne Yes /-Ne Yes I Ne Yes I Ne Yes I Ne Report. The staff review checklist is included as an attachment to this report. The licensee:
  • Provided a HF evaluation as described in NEI 12-06, Section H.4.2.
  • Appeared to follow the guidance for the HF evaluation.
  • Provided results of demand vs. capacity with identification of resolutions as needed. Yes I Ne Yes I No I NA Yes I No I NA Yes I No/ NA Notes from staff reviewer: The Millstone 2.1 Seismic HF evaluation (ADAMS Accession No. ML16365A036) encompassed the MSA HF scope. The NRC staff response to the Millstone HF confirmation is documented in letter dated February 13, 2017 (ADAMS Accession No. ML17038A035).

A table with HF evaluation results was provided in the MSA report. No modifications were required.

Deviation(s) or deficiency(ies) and Resolution:

None Consequence(s): None The NRC staff concludes:

  • The licensee's component capacity evaluation met the intent of the HF guidance.

VII. Conclusions

Yes /-Ne The NRC staff assessed the licensee's implementation of the MSA guidance for Millstone , Un i t 2. Based on its review , the NRC staff concludes that the licensee's implementation of the MSA meets the intent of the guidance.

The staff concludes that through the implementation of the MSA guidance, the licensee identified and evaluated the seismic capacity of the mitigating strategies equipment to ensure functionality will be maintained following a seismic event up to the GMRS. As noted in the review checklist, the staff identified one deviation and no exceptions taken from the guidance and the licensee did not identify any necessary equipment modifications or changes to the strategy. In summary, the NRC staff has reviewed the seismic hazard MSA for Millstone , Unit 2. The NRC staff conclud es that sufficient information has been provided to demonstrate that th e licensee's plans for the development and implement a tion of guidance a nd strategies under Order EA-12-049 appropriately address the reevaluated seismic hazard information stemming from the 50.54(f) letter. TECHNICAL REVIEW CHECKLIST BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO PATH FOUR MITIGATING STRATEGY ASSESSMENT MILLSTONE NUCLEAR POWER STATION, UNIT 3 DOCKET NO. 50-423 The NRG staff performed the following checklist review based on Attachment 2 of the April 27 , 2017 , letter for Millstone , Unit 3. Deviations, deficiencies , and conclusions are noted at the end of each section and an overall conclusion is provided at the end of the checklist.

I. Background and Assessment to MSSHI This section establishes basic background and assessment to MSSHI criteria in NEI 12-06, Appendix H. Licensee approach to MSA: Was the MSA conducted in accordance with NEI 12-06 , Revision 2 ¥es/ No as endorsed by the staff? Was the MSA conducted using an alternate method? Status of Order EA-12-049 Flexible Mitigation Strategy at the time of this review: Yes-/ Ne Has the licensee submitted a Final Integrated Plan? Yes/ Ne Has the NRG staff completed a safety evaluation for the mitigation Yes I Ne strategy?

Has the NRG staff confirmed compliance with Order EA-12-049 by Yes / Ne successfully completing the Tl-191 inspection?

Status of MSSHI Did the licensee use the GMRS and UHRS as submitted in response to the 50.54(f) request for information and reviewed by the NRG staff? Yes I Ne Has the plant equipment relied on for FLEX strategies previously been evaluated as seismically robust to the plant SSE levels? Is the maximum ratio of GMRS/SSE in the range of 1-10 Hz less than 2? Did the licensee meet the seismic evaluation cr i ter i a described in NEI 12-06 , Section H.5? Yes I No/ NA Yes I Ne Yes /-Ne Notes from staff reviewer: The GMRS/SSE ratio i s 1.28. This meets the criteria of NEI 12-06 , H.5. Deviation(s) or deficiency (ies) and Resolution:

The licensee performed this MSA using NEI 12-06 , Revision 4 , but as of the date of performance of the MSA , only Revis i on 2 has been endorsed by the NRC staff. The NRC staff has determined that working to Revision 4 is acceptable because there are no substantive differences between the two revisions i n the portions that are used for the MSA. Consequence(s)

None The NRC staff concludes:
  • The licensee meets the background and assessment to MSSHI criteria in NEI 12-06 , Appendix H. II. ESEP Equipment Equipment used in support of the FLEX strategies has been evaluated to demonstrate seismic adequacy following the guidance i n Section 5 of NEI 12-06. As stated in Appendix H of NEI 12-06 , previous seismic evaluations should be credited to the extent that they apply for the assessment of the MSSHI , including the ESEP evaluations performed i n accordance with EPRI 3002000704. Licensees may reference a previous ESEP submittal , submit a new or updated ESEP report , or provide other adequate justification or evaluation. Did the licensee previously perform an ESEP? Did the licensee provide a new or updated ESEP report w i th the MSA? Yes I Ne ¥es/ No ¥es/ No If the licensee did not perform ESEP , did they provide adequate justification that the expedited seismic equipment list (ESEL) structures , systems, and components (SSGs) are acceptable in accordance with the original guidance and in accordance with NEI 12-06 Section H.5 G 10% capacity criteria?

If the licensee did not perform the ESEP , did they perform an evaluation consistent with the guidance in NEI 12-06 , Section H.4.4 , Steps 2 and 3 , including the evaluation of FLEX components that were not previously evaluated to GMRS or 2 times the SSE? Yes I No I t-JA Yes I No I NA Notes from staff reviewer: Millstone did not perform ESEP as a stand-alone evaluation , but did provide an equipment list and evaluated ESEP scope of equipment consistent with the MSA guidance. The NRG staff audited the equipment list in Dominion document number R2730-003-001-3.

Deviation(s) or deficiency(ies) and Resolution

None Gonsequence(s):

None The NRG staff concludes:

  • The licensee has evaluated seismic adequacy of equipment used in support of FLEX strategy consistent with the NEI 12-06 , Appendix H guidance.

Ill Inherently I Sufficiently Ruqqed Equipment Appendix H , Section 4.4 of NEI 12-06 , Revision 2 documents the process and justification for inherently and sufficiently rugged SSGs. The licensee:

Documented the inherently and sufficiently rugged SSGs consistent with the NEI 12-06 , Appendix H guidance. Yes I Ne Yes I Ne Notes from staff reviewer:

Inherently rugged items are documented i n Section 2.3 of the Millstone MSA report. Deviation(s) or deficiency(ies) and Resolution:

None Gonsequence(s)

None The NRC staff concludes:
  • The licensee's assessment of inherently and sufficiently rugged SSCs met the intent of the NEI 12-06 , Appendix H guidance. IV Evaluation of Components Not Covered by ESEP ESEP specifically excluded the evaluation of certain components of the FLEX strategy in an effort to provide stakeholders with near-term confidence in a plant's seismic capacity.

However , licensees will be required to complete those evaluations as part of the Path 4 MSA to demonstrate compliance with the impending rule. Were the following components , not evaluated in the ESEP , evaluated as part of the MSA?:

  • FLEX Storage Building
  • Non-seismic CAT I structures
  • Operator Pathways credited in FLEX strategy
  • Tie down of FLEX portable equipment
  • Seismic interactions o Masonry block wall o Piping attached to tanks o Flooding from non-seismically robust tanks o Distributed systems (Piping/conduit/raceways/cable trays) o Other potential areas of interaction
  • FLEX equipment haul paths
  • Other equipment (list in Staff Reviewer Notes) Did the licensee prov i de adequate description/documentation of the evaluation?

Yes I Ne Yes I Ne Yes I Nol NA Yes I Ne Yes I Ne Yes I Ne Yes I Ne Yes I Ne Yes I Ne Yes I Ne Yes I Ne ¥-e&-1 No I-NA Yes I Ne Notes from staff reviewer:

The staff reviewed liquefaction potent i al evaluations for the FLEX building and FLEX equipment haul paths in Dominion calculations CE-2017 , Revision 0 and CE-2027, Revision 0. The NRC staff found that potential deformations to haul paths or the FLEX building would not prevent FLEX deployment.

Deviation(s) or deficiency(ies) and Resolution:

None Consequence(s):

None The NRC staff concludes:

  • The licensee followed the NEI 12-06 , Appendix H guidance in evaluating SSCs not deemed inherently rugged. V Spent Fuel Pool Coolinq Per NEI 12-06 , Appendix H , Section 4.4 , licensees need to evaluate the adequacy of SFP cooling equipment to the GMRS. Most plants include the Order EA-12-051 SFP Level Instrument as part of the strategy. The licensee:
  • Clearly identified the SSCs and locations of the equipment that is part of the final FLEX SFP cooling strategy.
  • Clearly stated the seismic design-basis (e.g. SSE) of the equipment used in the strategy.
  • Provided adequate description or documentation of the SFP cooling equipment's evaluat i on to the GMRS. Portable equipment and flexible hoses do not need to be evaluated.

Notes from staff reviewer: None Deviation(s) or deficiency(ies) and Resolution:

None Consequence(s)

None The NRC staff concludes:
  • The licensee followed the NEI 12-06 , Appendix H guidance in evaluating SFP cooling. VI. Hiqh Frequency Per NEI 12-06 , Appendix H , Section 4.4 , licensees with GMRS exceedance of the SSE above 1 O Hz need to evaluate bi-stable components such as relays using the methodology described in NEI 12-06 , Section H.4.2. The HF evaluation may have been submitted under separate letter or may be sent as an attachment to the MSA Yes I Ne Yes /-Ne Yes I Ne Yes I Ne Yes I Ne Report. The staff review checklist is included as an attachment to this report. The licensee:
  • Provided a HF evaluation as described in NEI 12-06, Section H.4.2.
  • Appeared to follow the guidance for the HF evaluation.
  • Provided results of demand vs. capacity with identification of resolutions as needed. Yes I Ne Yes I No I NA Yes I No I NA Yes I No I t>JA Notes from staff reviewer:

The Millstone 2.1 Seismic HF evaluation (ADAMS Accession No. ML16365A036) encompassed the MSA HF scope. The NRG staff response to the Millstone 2.1 HF confirmation is documented in letter dated February 13 , 2017 (ADAMS Accession No. ML17038A035).

A table with HF evaluation results was provided in the MSA report. No modifications were required.

Deviation(s) or deficiency(ies) and Resolution:

None Consequence(s):

None The NRG staff concludes:

  • The licensee's component capacity evaluation met the intent of the HF guidance.

VII. Conclusions:

Yes /-Ne The NRG staff assessed the licensee's implementation of the MSA guidance for Millstone , Unit 3. Based on its review, the NRG staff concludes that the licensee's implementation of the MSA meets the intent of the guidance.

The staff concludes that through the implementation of the MSA guidance, the licensee identified and evaluated the seismic capacity of the mitigating strategies equipment to ensure functionality will be maintained following a seismic event up to the GMRS. As noted in the review checklist , the staff identified one deviation and no exceptions taken from the guidance and the licensee did not identify any necessary equipment modifications or changes to the strategy.

In summary , the NRG staff has reviewed the seismic hazard MSA for Millstone , Unit 3. The NRG staff concludes that sufficient information has been provided to demonstrate that the licensee's plans for the development and implementation of guidance and strategies und er Order E A-12-049 appropriately a ddress the reevalu a ted seismic h aza rd inform a tion stemming from the 50.54(f) letter.

D. Stoddard MILLSTONE NUCLEAR POWER STATION, UNITS 2 AND 3 -STAFF REVIEW OF MITIGATING STRATEGIES ASSESSMENT REPORT OF THE IMPACT OF THE REEVALUATED SEISMIC HAZARD DEVELOPED IN RESPONSE TO THE MARCH 12, 2012, 50.54(f) LETTER DATED August 24, 2017 DISTRIBUTION:

PUBLIC JHMB R/F RidsNrrDorlLPL 1 Resource RidsNrrPMMillstone Resource RidsNrrLASLent Resource RidsAcrsAcnw_MailCTR Resource ADAMS Accession No. ML17202U682 SWyman, NRR BTitus, NRR EBowman, NRR NSanfilippo, NRR CWolf, OCA OFFICE NRR/JLD/JHMB

/PM NRR/JLD/LA NRR/JLD/JHMB/BC NAME SWyman SLent NSanfilippo DATE 8/3/1 7 8/3/17 8/18/17 OFFICIAL RECORD COPY *via e-mail OGC* NRR/JLD/JHMB/PM DCylkowski NLO SWyman 8/24/17 8/24/17

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