ML11122A117

Request for Additional Information Related to Generic Letter 2008-01, Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems

ML11122A117
Person / Time
Site:	Mcguire, McGuire
Issue date:	05/09/2011
From:	Jacqueline Thompson Plant Licensing Branch II
To:	Repko R Duke Energy Carolinas
Thompson J
References
TAC MD7843, TAC MD7844, GL-08-001
Download: ML11122A117 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 May 9, 2011 Mr. Regis T. Repko Vice President McGuire Nuclear Station Duke Energy Carolinas, LLC 12700 Hagers Ferry Road Huntersville, NC 28078 SUB,.IECT: MCGUIRE NUCLEAR STATION, UNITS 1 AND 2, REQUEST FOR ADDITIONAL INFORMATION (RAI) RELATED TO GENERIC LETTER (GL) 2008-01, "MANAGING GAS ACCUMULATION IN EMERGENCY CORE COOLING, DECAY HEAT REMOVAL, AND CONTAINMENT SPRAY SYSTEMS" (TAC NOS. MD7843 AND MD7844)

Dear Mr. Repko:

By letters dated October 13, 2008 (Agencywide Documents Access and Management System (ADAMS), Accession No. ML082900490), February 3, 2009 (ADAMS Accession No. ML090370415), January 6,2010 (ADAMS Accession No. ML100200272), and December 14, 2010 (ADAMS Accession No. ML103500133), Duke Energy Carolinas, LLC, submitted information in response to GL 2008-01 for the McGuire Nuclear Station, Units 1 and 2. The Nuclear Regulatory Commission (NRC) staff has reviewed the licensee's submittal and determined that additional information is needed in order to complete our review. The enclosed RAI describes this information. A written response should be provided to the NRC staff within 20 days of the issuance of this letter in order to support our timely review of this application.

Please inform me if you are unable to support this response timeframe.

If you have any questions, please call me at 301-415-1119.

Sincerely, Jon Thompson, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-369 and 50-370

Enclosure:

RAI cc w/encl: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION (RAI)

BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING GENERIC LETTER 2008-01. "MANAGING GAS ACCUMULATION IN EMERGENCY CORE COOLING.

DECAY HEAT REMOVAL, AND CONTAINMENT SPRAY SYSTEMS" TAC NOS. MD7843 AND MD7844 MCGUIRE NUCLEAR STATION. UNITS 1 AND 2 (MCGUIRE 1 AND 2)

DOCKET NOS. 50-369 AND 50-370 There have been several public meetings with Nuclear Energy Institute (NEI) and industry on the topic of GL 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems." The U.S. Nuclear Regulatory Commission (NRC) staff has continued to update its guidance to inspectors as new information becomes available; the most recent revision is Reference 2. At the June 2, 2010, public meeting (Meeting Summary at Agencywide Documents Access and Management System (ADAMS), Accession No. ML101650201) and in Reference 3, NRC and industry agreed on various void criteria including the Froude numbers required to credit dynamic venting.

Reference 2, Section 1.4.3, states, "At NFR :S 0.65, some gas may be transported and if NFR ~

2.0, all gas will be carried out of a pipe with the flowing water. Time to clear gas from a pipe for 0.8 < NFR < 2.0 is a function of flow rate. Dynamic venting may not be assumed effective for NFR

< 0.8. Time to clear gas as a function of time will be addressed in a later revision of this document when we have received and evaluated test data that supports clearance behavior .... "

Reference 1 states, " ... dynamic venting is credited (Froude number of > 0.55 for horizontal piping runs and >1.0 for vertical piping runs)."

The NRC staff has the following questions:

1. Please provide justification for crediting dynamic venting with Froude numbers between 0.55 and 0.8.

2. Please clarify if an Ultrasonic Test (UT) is used at McGuire 1 and 2 to verify that dynamically flushed piping remains sufficiently full with respect to such areas as vertical U-tube heat exchangers and valve internal configurations where UT cannot be used if dynamic flushing involves these locations. If dynamic flushing is not used for these areas, then describe how they are determined to be sufficiently full.

Enclosure

- 2 REFERENCES

1. Letter from Thomas P. Harrall, Duke Energy, to Document Control Desk, NRC, "Duke Energy Carolinas, LLC (Duke); Oconee Nuclear Station, Units 1, 2, and 3, Docket Nos.

50-269, 50-270, 50-287; McGuire Nuclear Station, Units 1 and 2, Docket Nos. 50-369, 50-370; Catawba Nuclear Station, Units 1 and 2, Docket Nos. 50-413, 50-414; Generic Letter 2008-01, 9-Month Response," October 13, 2008 (ADAMS Accession No. ML082900490).

2. "Guidance To NRC/NRRIDSS/SRXB [Reactor Systems Branch, Division of Safety Systems, Office of Nuclear Reactor Regulation, NRC] Reviewers for Writing TI

[Temporary Instruction] Suggestions for the Region Inspections," December 6,2010 (ADAMS Accession No. ML103400347).

3. Electronic mail from Warren Lyon, NRC, to J. Riley, NEI, "RE: Interim Clean Section 1 4 (3).docx," June 7, 2010 (ADAMS Accession No. ML102090074).

May 9,2011 Mr. Regis 1. Repko Vice President McGuire Nuclear Station Duke Energy Carolinas, LLC 12700 Hagers Ferry Road Huntersville, NC 28078 SUB..IECT: MCGUIRE NUCLEAR STATION, UNITS 1 AND 2, REQUEST FOR ADDITIONAL INFORMATION (RAI) RELATED TO GENERIC LETTER (GL) 2008-01, "MANAGING GAS ACCUMULATION IN EMERGENCY CORE COOLING, DECAY HEAT REMOVAL, AND CONTAINMENT SPRAY SYSTEMS" (TAC NOS. MD7843 AND MD7844)

Dear Mr. Repko:

By letters dated October 13, 2008 (Agencywide Documents Access and Management System (ADAMS), Accession No. ML082900490), February 3,2009 (ADAMS Accession No. ML090370415), January 6,2010 (ADAMS Accession No. ML100200272), and December 14, 2010 (ADAMS Accession No. ML103500133), Duke Energy Carolinas, LLC, submitted information in response to GL 2008-01 for the McGuire Nuclear Station, Units 1 and 2. The Nuclear Regulatory Commission (NRC) staff has reviewed the licensee's submittal and determined that additional information is needed in order to complete our review. The enclosed RAI describes this information. A written response should be provided to the NRC staff within 20 days of the issuance of this letter in order to support our timely review of this application.

Please inform me if you are unable to support this response timeframe.

If you have any questions, please call me at 301-415-1119.

Sincerely, IRA!

Jon Thompson, Project Manager Plant licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-369 and 50-370

Enclosure:

RAI cc w/encl: Distribution via Listserv DISTRIBUTION:

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