ML12110A194

Catawba Nuclear Station, Units 1 and 2, and McGuire Nuclear Station, Units 1 and 2 - Request for Additional Information - 50.46, 30-Day Report Regarding Thermal Conductivity Degradation in the Westinghouse-Furnished Realistic Emergency Core

ML12110A194
Person / Time
Site:	Mcguire, Catawba, McGuire
Issue date:	04/23/2012
From:	Thompson J H Plant Licensing Branch II
To:	Morris J R, Repko R T Duke Energy Carolinas
Thompson J H
References
TAC ME8447, TAC ME8448, TAC ME8449, TAC ME8450
Download: ML12110A194 (5)

Text

UNITED NUCLEAR REGULATORY WASHINGTON, D.C. 20555-0001 April 23, 2012 Mr. J. R. Morris Site Vice President Catawba Nuclear Station Duke Energy Carolinas, LLC 4800 Concord Road York, SC 29745 Mr. Regis T. Repko Vice President McGuire Nuclear Station Duke Energy Carolinas, LLC 12700 Hagers Ferry Road Huntersville, NC 28078 CATAWBA NUCLEAR STATION, UNITS 1 AND 2 (CATAWBA 1 AND 2), MCGUIRE NUCLEAR STATION, UNITS 1 AND 2 (MCGUIRE 1 AND REQUEST FOR ADDITIONAL INFORMATION -50.46, 30-DAY REPORT REGARDING THERMAL CONDUCTIVITY DEGRADATION IN THE WESTINGHOUSE-FURNISHED REALISTIC EMERGENCY CORE COOLING EVALUATION (TAC NOS. ME8447, ME8448, ME8449, AND ME8450) Dear Messrs. Morris and Repko: By letter dated March 16, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML 12079A180), Duke Energy Carolinas, LLC (the licensee), submitted a response to an NRC staff information request pursuant to Title 10 Code of Federal Regulations (10 CFR), Section 50.54(f) related to the estimated effect on peak cladding temperature resulting from thermal conductivity degradation in the Westinghouse-furnished realistic emergency core cooling evaluation. The licensee also stated that this response served as a 30-day report of a significant emergency core cooling system evaluation model change or error in accordance with requirements of 10 CFR 50.46(a)(3). In the course of the U.S. Nuclear Regulatory Commission's (NRC's) staff review of the 30-day report submitted in accordance with 10 CFR 50.46(a)(3), it was determined that additional information is necessary for the NRC staff to complete its review. A request for additional information (RAI) was provided to the licensee by email dated March 26,2012 (ADAMS Accession No. ML 1211 OA336), to facilitate discussion between the NRC staff and the licensee and to enable the licensee to respond to the NRC request in a timely manner. Subsequently, the NRC staff conducted an audit at the Westinghouse Electric Company facilities in Cranberry Township, Pennsylvania, to further clarify the RAI and to further delineate the content required to be responsive to the RAI (audit plan at ADAMS Accession No. ML 12101A118). As discussed during the audit, the initial RAt has been modified, as reflected in the enclosure, to provide additional clarity. A response from the licensee is requested within 30 days of transmittal of the request to the licensee.

J. Morris and R. Repko -2 If you have any questions on this matter, please contact 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, 50-414, 50-369, and 50-370 Enclosure: As stated cc w/encl: Distribution via Listserv REQUEST FOR ADDITIONAL BY THE OFFICE OF NUCLEAR REACTOR REGARDING 10 CFR 50.46 30-DA Y REPORT THERMAL CONDUCTIVITY DEGRADATION IN THE REALISTIC EMERGENCY CORE COOLING CATAWBA NUCLEAR STATION, UNITS 1 AND 2 (CATAWBA 1 AND DOCKET NOS. 50-413 AND MCGUIRE NUCLEAR STATION. UNITS 1 AND 2 (MCGUIRE 1 AND DOCKET NOS. 50-369 AND Your submittal referenced a March 7,2012, letter sent by Westinghouse Electric Company to the NRC. The final paragraph on Page 2 of 9 refers to small differences in fuel characteristics that were claimed to be compared. The paragraph also discusses confirmatory evaluations concluding that other operating characteristics were acceptable. Provide the results of this comparison for Catawba Nuclear Station, Units 1 and 2 and McGuire Nuclear Station, Units 1 and 2, including the relevant conclusions and the technical basis supporting those conclusions. For any conclusion that differences in void volume are offset by other conservatisms, list those conservatisms and provide a quantitative estimate of each conservatism, as well as a brief description of the rigor associated with that estimate. Please provide the values for the coefficients A 1 and A2 used in the PAD 4.0 + TCD U02 thermal conductivity equation. Please explain any error corrections, code improvements, and miscellaneous code cleanup between the WCOBRAITRAC and HOTSPOT code Versions used in the TCD evaluations and those used in the plant's AOR. What is the thermal conductivity model impact of code version changes in HOTSPOT? Explain the differences between the HOTSPOT and PAD thermal conductivity models and the impact of those differences. Provide graphs or other quantified descriptions that aid in explanation. Enclosure Please provide additional details concerning the steady-state ASTRUM/CQD initialization process. In particular, please explain what fuel characteristics are adjusted within the applicable models to obtain convergence among HOTSPOT, TRAC, and PAD4.0TCD. Please explain how any changed design values will be verified during operation of the plant (Le. TS limits, Surveillances, etc). Also, explain what compensatory actions will be taken if a value is found to be outside of the limits assumed in the analysis.

J. Morris and R. Repko -If you have any questions on this matter, please contact 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, 50-414, 50-369, and 50-370 Enclosure: As stated cc w/encl: Distribution via Listserv DISTRIBUTION: PUBLIC LPL2-1 R/F RidsRgn2MailCenter JMiller, NRR RidsAcrsAcnw_MailCTR RidsNrrDirsltsb JPaige, NRR DWoodyatt, NRR RidsNrrDorlLpl2-1 RidsNrrDoriDpr BParks, NRR JGall, NRR RidsNrrDssSrxb RidsNrrLASFigueroa REul,OE AUlses, NRR RidsNrrPMCatawba RidsNrrPMMcGuire RidsOgcRp ADAMS Accession No. ML1211OA194

• No significant chan e to input submitted OFFICE NRR/LPL2-1/PM NRR/LPL2-1/LA NRRISRXB/BC* NRR/LPL2-1/BC NRR/LPL2-1/PM NAME JThompson SFigueroa AUlses NSalgado JThompson DATE 04/23/12 04/19/12 04/16/12 04/23/12 04/23/12 OFFICIAL RECORD COPY