ML12116A147

Further Request for Additional Information - 50.46, 30-Day Report Regarding Thermal Conductivity Degradation in the Westinghouse-Furnished Realistic Emergency Core Cooling

ML12116A147
Person / Time
Site:	Catawba, McGuire, Mcguire
Issue date:	04/27/2012
From:	Jacqueline Thompson Plant Licensing Branch II
To:	Morris J, Repko R Duke Energy Carolinas
Thompson J
References
TAC ME8447, TAC ME8448, TAC ME8449, TAC ME8450
Download: ML12116A147 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 April 27, 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 SUB..IECT: CATAWBA NUCLEAR STATION, UNITS 1 AND 2 (CATAWBA 1 AND 2),

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

FURTHER 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. ML12079A180), 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 was 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. ML12110A336), 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 Ac<;ession No. ML12101A118).

As discussed during the audit. modifying the initial RAI would provide additional clarity for the NRC staff's information needs and this modified RAI was sent to the licensee by the NRC staff by letter dated April 23, 2012 (ADAMS Accession No ML12110A194)

J. Morris and R. Repko - 2 After further review and discussion by the NRC staff it was determined that a further RAI was required for the NRC staff to complete its review. This RAI is enclosed with this letter. A response from the licensee to this RAI is requested within 30 days of transmittal of this request to the licensee and the response to the RAI sent by letter dated April 23, 2012, can be provided at this time as well.

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 INFORMATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING 10 CFR 50.46 30-DAY REPORT ON THERMAL CONDUCTIVITY DEGRADATION IN THE REALISTIC EMERGENCY CORE COOLING EVALUATION CATAWBA NUCLEAR STATION. UNITS 1 AND 2 (CATAWBA 1 AND 2)

DOCKET NOS. 50-413 AND 50-414 MCGUIRE NUCLEAR STATION, UNITS 1 AND 2 (MCGUIRE 1 AND 2)

DOCKET NOS. 50-369 AND 50-370 By letter dated March 16, 2012 (Agencywide Documents Access and Management System Accession No. ML12079A180), 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 (TCD) in the realistic emergency core cooling evaluation furnished by Westinghouse Electric Company. 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).

After review by the NRC staff, it was determined that another request for additional information (RAI) was needed regarding the compensatory measures that the licensees implemented to offset the effects of the TCD error. Specifically, the NRC staff has a concern that the actions taken by the licensee may constitute a methodology change and an evaluation in accordance with 10 CFR 50.59, which would direct them to submit a license amendment request to include these compensatory measures in their updated final safety analysis report (UFSAR). Further, the licensee committed to submit a revised evaluation by 2016 and the NRC staff wants to verify that the licensee is taking the appropriate actions to maintain the validity of the compensatory measures during this timeframe (per Nuclear Energy Institute guidance, directing 10 CFR 50.59 evaluations for temporary alterations that are in effect longer than 90 days at power). The NRC staff's RAI is as follows:

In its letter dated March 16, 2012, the licensee it appears to have revised inputs to a method of evaluation as described in the UFSAR used in establishing the design bases or in the safety analyses. The licensee should respond as to whether the methodology permits the licensee to establish how to select the value of an input parameter to yield adequately conservative results and whether the revised value is more conservative than that required by the selection method.

Further, address whether any of the changes (e.g., to the uranium dioxide thermal conductivity equation) constitute a change in the calculational framework used for evaluating behavior or response of a system, structure or component.

Enclosure

ML12116A147 OFFICE NRR/LPL2-1/PM NRRlLPL2-1/LA NRRISRXB/BC*

NAME JThompson SFigueroa AUlses JThompson DATE 04/27112 04/25/12 04/23112 04/27/12