ML14175B667

2014/06/20 NRR E-mail Capture - Darft RAIs on Millstone Unit2 IPEEE for Public Meeting June 25 2014

ML14175B667
Person / Time
Site:	Millstone
Issue date:	06/20/2014
From:	Balazik M F Japan Lessons-Learned Division
To:	Craft W D Dominion Energy Co
References
Download: ML14175B667 (4)

Text

1NRR-PMDAPEm Resource From:Balazik, Michael Sent:Friday, June 20, 2014 1:12 PM To:wanda.d.craft@dom.com Cc:DiFrancesco, Nicholas; Jackson, Diane; Uribe, Juan; Thadani, Mohan

Subject:

DARFT RAIs on Millstone Unit2 IPEEE for Public Meeting June 25 2014 Ms. Craft, By letter to the Nuclear Regulatory Commission (NRC) dated March 31, 2014 (Agencywide Documents and Management System (ADAMS) (public) Accession No. ML14092A417), Dominion (the licensee), submitted for NRC review the Response to March 12, 2012 Information Request Seismic Hazard and Screening Report for Recommendation 2.1 for Millstone Power Station (Millstone), Units 2 and 3.

The NRC staff has reviewed the information provided for Millstone, Units 2 and 3, and has determined that additional information is required to complete its review. The draft requests for additional information (RAIs) related to the NRC staff review are provided below.

After reviewing the draft RAIs, please contact me by email or by phone at 301-415-2856 to discuss the need for a teleconference to clarify the draft RAIs and to establish a due date for the response.

Optionally, Dominion has an opportunity to discuss the RAIs in the upcoming public meeting with the NRC on June 25, 2014. There is no staff expectation for Dominion to provide a final answer at this venue.

Respectfully, Michael Balazik Project Manager U.S. Nuclear Regulatory Commission

Office of Nuclear Reactor Regulation Japan Lesson Learned Project Directorate

michael.balazik@nrc.gov l Tel: (301) 415-2856

DRAFT REQUEST FOR ADDITIONAL INFORMATION MILLSTONE POWER STATION UNIT 2 DOCKET NOS. 50-336

Millstone Power Station Unit 2 After reviewing Individual Plant Examination of External Events (IPEEE) Adequacy Evaluation and IPEEE High Confidence of a Low Probability of Failure (HCLPF) spectra (IHS) Development part of the Seismic Hazard and Screening Report for Millstone Power Station Unit 2 (MPS2), herein called Appendix B, and the earlier IPEEE submittal for MPS2, the NRC staff has two main requests for clarification as described below. The information 2on the clarifications will be reviewed by the NRC staff as part of the NRC staff evaluation of the IPEEE adequacy and, if needed, to support a follow-on audit of the items addressed in the requests.

Request 1 As part of Appendix B, the licensee submitted a Peer-Review report which reviewed the HCLPF capacity calculations used in the IPEEE Seismic Margin Analysis (SMA). Table 2 of the Peer-Review report lists 6 components for which the HCLPF peak ground acceleration (PGA) in the IPEEE report for MPS2 is less that the plant HCLPF of 0.25g as shown in the table below (herein all HCLPFs are defined in terms of a 5-percent damping NUREG/CR-0098 rock spectral shape with the referred to PGA).

In agreement with the licensee submittal, Table 2 of the Peer-Review report describes how failure of three of those 6 structures, systems, and components (SSC) no longer affects the plant HCLPF and indicates that after a modification the revised HCLPF for another SSC increased to 0.29g. These components are the first four components in the table below.

The conclusion of the Peer-Review report is that once the licensee satisfactorily completes the actions listed in the notes column of the table below for the Battery Racks DB1 and DB1 and for the Chilled Water Surge Tank, the plant level IPEEE HCLPF can be considered to be the NUREG/CR-0098 spectral shape (5-percent damping) anchored at 0.25g PGA.

SSC SSC HCLPF Notes Table 3.2-3 IPEEE report S&A Calculation

Sheets 22S3-2-2 RSST Feeder

Breaker 0.19 0.19 Failure of enclosure no longer affects the

plant HCLPF (after a plant modification) Block Wall 7.8

near Inverter 5 0.051 0.051 Failure does affect plant HCLPF Inverter 5 Failure does affect plant HCLPF 120V AC Panel

VR11 and VR21 0.17 0.17 Following modifications the calculated HCLPF is 0.29g Battery Racks DB1 and DB2 (Battery 201A

201B) 0.13 0.061 Dominion will locate and existing HCLPF calculation or reconstitute a calculation to

confirm that the HCLPF capacity is greater than 0.25g Chilled Water Surge Tank 0.22 0.136 Dominion will locate and existing HCLPF calculation or reconstitute a calculation to

confirm that the HCLPF capacity is

greater than 0.25g

3In Appendix B (Section B5.6, page B-24), the licensee states that subsequently to the Peer-Review report field walkdowns and evaluations were performed to reconstitute the HCLPF calculations for these two SSCs (Battery Racks DB1 and DB1, and the Chilled Water Surge Tank). The conclusion in page B-24 of Appendix B is that the HCLPF capacity for each of these SSCs remains greater than or equal to the plant HCLPF capacity of 0.25g through modifications previously performed and/or evaluation of the as-built configuration. Appendix B refers to Dominion Engineering Technical Evaluation ETE-CEM-2014-0001 (Reference B7.27 of Appendix B) for the documentation of the evaluation of these two SSCs.

The new evaluations and related modifications result in an increase of the HCLPF for the two SSCs that are significant for the safety assessment, the Battery Racks DB1 and DB1, and the Chilled Water Surge Tank. However, these evaluations and modifications were not part of the IPEEE documentation previously reviewed by the NRC staff and were not part of the evaluations reviewed in the Peer-Review Report in Appendix B. To un derstand the details, scope and inputs for these new evaluations and related modifications for these two SSCs, the NRC staff requests:

• A detailed description of the methods and inputs for the new evaluations including how the new evaluations differed from the earlier evaluations for the MPS2 IPEEE, how the SSCs configurations changed from previously made modifications, and how the understanding of the as-built conditions changed from the earlier evaluations.

• A detailed description of the modifications to these SSCs, if any.

Request 2 Table 7.1-1, Opportunities for Safety Enhancements, of the IPEEE submittal for MPS2 lists two SSCs identified as "items to be resolved". It is written in Table 7.1-1 that these two items are on the USI A-46 Safe Shutdown Equipment List (SSEL) and were being tracked under USI A-46. It is also written in Table 7.1-1 that the IPEEE program would support resolution of these items by providing relative risk significance of this issue in relation to all other USI A-46 issues. One of these two items was resolved with the Near Term Task Force 2.3 walkdowns. The remaining item is:

• Air operated valve 2-CHW-11, which has a heavy yoke that is independently braced.

The NRC staff requests the following:

• Detailed description on how was this item was resolved and what is its safety significance, if any, in terms of the plant IPEEE HCLPF of 0.25g.

Hearing Identifier: NRR_PMDA Email Number: 1398 Mail Envelope Properties (Michael.Balazik@nrc.gov20140620131100)

Subject:

DARFT RAIs on Millstone Unit2 IPEEE for Public Meeting June 25 2014 Sent Date: 6/20/2014 1:11:37 PM Received Date: 6/20/2014 1:11:00 PM From: Balazik, Michael Created By: Michael.Balazik@nrc.gov Recipients: "DiFrancesco, Nicholas" <Nicholas.DiFrancesco@nrc.gov> Tracking Status: None "Jackson, Diane" <Diane.Jackson@nrc.gov>

Tracking Status: None "Uribe, Juan" <Juan.Uribe@nrc.gov> Tracking Status: None "Thadani, Mohan" <Mohan.Thadani@nrc.gov> Tracking Status: None "wanda.d.craft@dom.com" <wanda.d.craft@dom.com> Tracking Status: None Post Office: Files Size Date & Time MESSAGE 6956 6/20/2014 1:11:00 PM

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