ML11094A019

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

ML11094A019
Person / Time
Site:	Catawba
Issue date:	04/07/2011
From:	Jacqueline Thompson Plant Licensing Branch II
To:	Morris J Duke Energy Carolinas
Thompson, Jon DORL/LPL2-1 415-1119
References
TAC MD7809, TAC MD7810, GL-08-001
Download: ML11094A019 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 April 7, 2011 Mr. J. R. Morris Site Vice President Catawba Nuclear Station Duke Energy Carolinas, LLC 4800 Concord Road York, SC 29745

SUBJECT:

CATAWBA 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. MD7809 AND MD7810)

Dear Mr. Morris:

By letter dated October 13, 2008, and March 4, 2010, Duke Energy Carolinas, LLC, submitted information in response to GL 2008-01 for the Catawba 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 document describes this RAI. A written response should be provided to the NRC staff within 30 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. 50-413 and 50-414

Enclosure:

RAI cc w/encl: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION (RA\)

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. MD7809 AND MD7810)

CATAWBA NUCLEAR STATION, UNITS 1 AND 2 (CATAWBA 1 AND 2)

DOCKET NOS. 50-413 AND 50-414 By letters dated October 13.2008 (Reference 1). and March 4.2010 (Reference 2). Duke Energy Carolinas, LLC (Duke, the licensee), submitted information in response to Generic Letter (GL) 2008-01 "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal.

and Containment Spray Systems." for Catawba 1 and 2.

On the basis of the provided information, the Nuclear Regulatory Commission (NRC) staff has concluded that additional information is required from the licensee in order for the NRC staff to determine that the licensee has acceptably demonstrated "that the subject systems are in compliance with the current licensing and design bases and applicable regulatory requirements, and that suitable design, operational, and testing control measures are in place for maintaining this compliance" as stated in GL 2008-01.

There have been several public meetings with Nuclear Energy Institute (NEI) and industry on the topic of GL 2008-01. The NRC staff has continued to update its guidance to inspectors as new information becomes available; the most recent revision is Reference 3. At the public meeting on June 2,2010 (Meeting Summary at Agencywide Documents Access and Management System (ADAMS), Accession No. ML101650201), between the NRC staff and NEI, and in Reference 4, the NRC staff and industry agreed on various void criteria, including the Froude numbers required to credit dynamic venting.

Reference 3, Section 1.4.3, states, "At NFR [Froude Number] 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)."

Reference 2 clarifies this by stating, 'The criteria used was derived from WCAP-16631-NP."

Reference 2 went on to say, "It is acknowledged that gas may be removed from piping at lower Froude numbers. In the end, UT [ultrasonic testing] was conducted at numerous points on the subject systems and the piping was found to be full with the one exception mentioned above."

Enclosure

-2 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 verify the statement that UT is used 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.

REFERENCES

1. Letter from Thomas P. Harrall, Duke, to Document Control Desk (DCD), NRC, "Duke Energy Carolinas, LLC (Duke); Oconee Nuclear Station, Units 1, 2 & 3, Docket Nos. 50 269, 50-270, 50-287; McGuire Nuclear Station, Units 1 & 2, Docket Nos. 50-369, 50 370; Catawba Nuclear Station, Units 1 & 2, Docket Nos. 50-413,50-414; Generic Letter 2008-01, 9-Month Response," dated October 13,2008 (ADAMS Accession No. ML082900490).

2. Letter from James R. Morris, Duke, to DCD, NRC "Response to Request for Additional Information Regarding Generic Letter 2008-01, 'Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems, ",

dated March 4, 2010, (ADAMS Accession No. ML100640548).

3. NRC Regulatory Guidance, "Guidance To NRC/NRR/DSS/SRXB Reviewers for Writing TI [Temporary Instruction] Suggestions for the Region Inspections," dated December 6, 2010 (ADAMS Accession No. ML103400347).

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

April 7, 2011 Mr. J. R. Morris Site Vice President Catawba Nuclear Station Duke Energy Carolinas, LLC 4800 Concord Road York, SC 29745

SUBJECT:

CATAWBA 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. MD7809 AND MD7810)

Dear Mr. Morris:

By letter dated October 13,2008, and March 4,2010, Duke Energy Carolinas, LLC, submitted information in response to GL 2008-01 for the Catawba 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 document describes this RAI. A written response should be provided to the NRC staff within 30 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. 50-413 and 50-414

Enclosure:

RAI cc w/encl: Distribution via Listserv DISTRIBUTION:

PUBLIC RidsNrrLAMOBrien Resource (hard copy)

LPL2-1 R/F RidsNrrPMCatawba Resource (hard copy)

RidsAcrsAcnw_MailCTR Resource RidsOgcRp Resource RidsNrrDirsltsb Resource RidsRgn2MailCenter Resource RidsNrrDorlLpl2-1 Resource JGall, NRR RidsNrrDorlDpr Resource AUlses, NRR RidsNrrDssSrxb Resource MO'Brien AUlses* GKulesa JThompson 04/6/11 02108/11 04/7111 0417111 OFFICIAL RECORD COPY