ML17264A282

Request for Additional Information Re Systematic Risk-Informed Assessment of Debris Technical Report

ML17264A282
Person / Time
Site:	Vogtle
Issue date:	10/12/2017
From:	Michael Orenak Plant Licensing Branch II
To:	Hutto J Southern Nuclear Operating Co
Orenak, M D, NRR/DORL/LPLII-1, 415-3229
References
CAC MF9685, CAC MF9686
Download: ML17264A282 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 October 12, 2017 Mr. James J. Hutto Regulatory Affairs Director Southern Nuclear Operating Co., Inc.

P.O. Box 1295, Bin 038 Birmingham, AL 35201-1295

SUBJECT:

VOGTLE ELECTRIC GENERATING PLANT, UNITS 1AND2- REQUEST FOR ADDITIONAL INFORMATION RE SYSTEMATIC RISK-INFORMED ASSESSMENT OF DEBRIS TECHNICAL REPORT (CAC NOS. MF9685 AND MF9686)

Dear Mr. Hutto:

By letter dated April 21, 2017 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML17116A096) as supplemented by letter dated July 11, 2017 (ADAMS Accession No. ML17192A245), Southern Nuclear Operating Company, Inc. submitted a plant-specific technical report for Vogtle Electric Generating Plant, Units 1 and 2, and requested U.S. Nuclear Regulatory Commission (NRC) approval of the methods and inputs described in the technical report. The plant-specific technical report describes a risk-informed methodology to evaluate debris effects with the exception of in-vessel fiber limits.

The NRC staff has reviewed the submittal and has determined that additional information is needed to complete its review. Enclosed is the NRC staff's request for additional information (RAI). The RAI was discussed with your staff on September 26, 2017, and it was agreed that your response would be provided within 30 days from the date of this letter.

Sincerely, Michael L. Marshall, Jr., Senior Project Manager Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-424 and 50-425

Enclosure:

Request for Additional Information cc: Listserv

REQUEST FOR ADDITIONAL INFORMATION REGARDING SYSTEMATIC RISK-INFORMED ASSESSMENT OF DEBRIS TECHNICAL REPORT, SOUTHERN NUCLEAR OPERATING COMPANY, INC.

VOGTLE ELECTRIC GENERATING PLANT. UNITS 1AND2 SOUTHERN NUCLEAR OPERATING COMPANY DOCKET NOS. 50-424 AND 50-425 By letter dated April 21, 2017 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML17116A096) as supplemented by letter dated July 11, 2017 (ADAMS Accession No. ML17192A245), Southern Nuclear Operating Company, Inc. (SNC) submitted a plant-specific technical report for Vogtle Electric Generating Plant, Units 1 and 2 (VEGP), and requested U.S. Nuclear Regulatory Commission (NRC) approval of the methods and inputs described in the technical report. The plant-specific technical report describes a risk-informed methodology to evaluate debris effects with the exception of in-vessel fiber limits.

The NRC staff reviewed the submittal and determined that the enclosed additional information is needed to complete its review. The requests for additional information (RAls) listed below are not a complete listing of the additional information needed to complete the NRC staff's review. Additional RAls will be provided via separate correspondence.

(1) In Table 3-9 on pages E3-40 to E3-59 of Enclosure 3 to the letter dated April 21, 2017, the licensee provides a lists information for all Class 1 welds that are considered in the GSl-191 analysis. On Pages E3-42 and E3-43, the licensee states that 4 cold leg welds are assumed to have primary water stress corrosion cracking (PWSCC) degradation mechanism in the sump analysis. Please provide an explanation as to why:

a. PWSCC is not assumed for hot leg welds.

b. The 4 cold leg welds resulted in no sump failures even though the cold leg welds are assumed to have PWSCC which will lead to weld failures.

(2) In Section 2.3.2 on page E4-11 of Enclosure 4 to the letter dated April 21, 2017, the licensee states, in part, that:

The inservice inspection (ISi) program provides rules for the examination and repair of piping and other RCS [reactor coolant system] components, and plays an important role in the prevention of pipe breaks. The integrity of the Class 1 welds, piping, and components are maintained at a high level of reliability through the ASME Section XI inspection program [the 201 O edition,]

Enclosure

(Reference 6). VEGP ISi procedures also ensure that inspections are performed in accordance with the schedule requirements of the code.

a. Please identify the welds that are mitigated to minimize PWSCC and the associated mitigation method(s) for those welds.

b. Please identify the Alloy 82/182 welds that have not been mitigated.

c. Please discuss any flaws or indications that have been detected, but not repaired, in any of the welds that are considered in the GSl-191 evaluation.

(3) In Section 2.3.2 on page E4-11 of Enclosure 4 to the letter dated April 21, 2017, the licensee states, in part, that:

The leak detection program at VEGP is capable of early identification of RCS leakage in accordance with RG [Regulatory Guide] 1.45, Revision 1, ["Guidance on Monitoring and Responding to Reactor Coolant System Leakage," May 2008,]

(Reference 8) to provide time for appropriate operator action to identify and address RCS leakage ...

Please discuss any changes or enhancement, if any, to the RCS leakage detection systems after Revision 16 of Chapter 5.0, "Reactor Coolant System and Connected Systems," of the VEGP Updated Final Safety Analysis Report was provided to the NRG.

ML17264A282 OFFICE NRR/DORL/LPL 1/PM NRR/DORL/LPL2-1 /PM NRR/DORL/LPL2-1/LA NAME MMarshall MOrenak KGoldstein DATE 10/02/17 10/04/17 10/04/17 OFFICE NRR/DE/EPNB/BC NRR/DORL/LPL2-1 /BC NRR/DORL/LPL 1/PM NAME DAiiey MMarkley MMarshall DATE 10/10/17 10/12/17 10/12/17