ML120110167

Request for Additional Information, Regarding Proposed Technical Specification Safety Limit Minimum Critical Power Ratio Changes

ML120110167
Person / Time
Site:	LaSalle
Issue date:	01/19/2012
From:	Nicholas Difrancesco Plant Licensing Branch III
To:	Pacilio M Exelon Nuclear, Exelon Generation Co
DiFrancesco N, NRR/DORL/LPL3-2, 415-1115
References
TAC ME7331
Download: ML120110167 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 January 19, 2012 Mr. Michael J. Pacilio President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

LASALLE COUNTY STATION, UNIT 1 - REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED TECHNICAL SPECIFICATION SAFETY LIMIT MINIMUM CRITICAL POWER RATIO CHANGES (TAC NO. ME7331)

Dear Mr. Pacilio:

By letter dated October 12,2011 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML112860067), Exelon Generation Company, LLC submitted a license amendment request proposing to modify the safety limit minimum critical power ratios contain in Section 2.1 of the technical specifications at LaSalle County Station (LSCS), Unit 1.

The basis for the proposed revision was a cycle-specific analysis performed to support operation of LSCS, Unit 1, in the upcoming Cycle 15.

The NRC staff is reviewing your submittal and has determined that additional information is required to complete the review. The specific information requested is addressed in the enclosure to this letter. During a discussion with your staff on January 19, 2012, it was agreed that you would provide a response by February 10, 2012.

Please note that if you do not respond to this letter by the agreed-upon date or provide an acceptable alternate date in writing, we may reject your request for approval under the provisions of Title 10 of the Code of Federal Regulations, Section 2.108.

The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRC's goal of efficient and effective use of staff resources.

Please contact me at 301-415-1115 if you have any questions.

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icholas DiFrancesco, Project Manager Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear reactor Regulation Docket No. 50-373

Enclosure:

As stated cc w/encl: Distribution via ListServ

REQUEST FOR ADDITONAL INFORMATION LASALLE COUNTY STATION, UNIT 1 LICENSE AMENDMENT REQUEST REGARDING PROPOSED SAFETY LIMIT MINIMUM CRITICAL POWER RATION CHANGE DOCKET NO. 50-373 By letter dated October 12, 2011 (Agencywide Documents Access and Management System Accession (ADAMS) Accession No. ML112860067), Exelon Generation Company LLC (Exelon, the licensee) submitted a license amendment request (LAR) proposing to modify technical specification (TS) Section 2.1, "Safety Limits," for LaSalle County Station (LSCS), Unit 1. The requested change involved revised safety limit minimum critical power ratios (SLMCPRs) calculated as a result of the cycle-specific analysis performed by Global Nuclear Fuel (GNF) to support operation in the upcoming LSCS, Unit 1, Cycle 15. The U.S. Nuclear Regulatory Commission (NRC) staff has been reviewing the submittal and has determined that additional information is needed to complete its review.

1. In the LAR, Attachment 6, Tables RAI-06-1 and RAI-06-2, provide core map to show those bundles experienced 0.1 boiling transition criterion of limiting cases for single-loop operation (SLO) and two-loop operation (TLO). Please provide identification of bundle group and number of bundles in the Figure 1, Attachment 5, corresponding to their burnup status (once-burned, twice-burned, or fresh fuel) for Cycle 15.

2. Core design is an iterative process designed to develop an optimal configuration that meets operational requirements. In the LAR, Attachment 7, for the slides titled "Pre-Estimation

- Linear Reactivity," please provide the most current updated parameters applicable to LSCS, Unit 1! Cycle 15. Also, provide the details of a plant-specific final core loading pattern as shown in Figure 1 including core design procedures, guidelines, criteria, and approved methodologies used for this Cycle 15 analysis with respect to a mixed core application.

3. GNF2 fuel deviates from traditional 1Ox1 0 design through the introduction of a partial length rod configuration, the use of higher linear power, and the use of mixing vanes. The NRC staff considers this a new fuel design with regards to the four restrictions identified in the safety evaluation of General Electric (GE) Licensing Topical Reports NEDC-32601 P, NEDC 32694, and Amendment 25 to NEDE-24011-P-A. Given that LSCS, Unit 1, Cycle 15, uses a core loading pattern which includes GNF2 fuel, provide the following: (1) an evaluation of the four restrictions in NEDC-32601 P, NEDC-32694 and Amendment 25 to NEDE-24011-P-A and the applicability to mixed core with ATRIUM 10 fuel; (2) a description that explains under what conditions the methodologies listed in Section 1.0 of Attachment 5 are sufficient and applied to the LSCS, Unit 1, Cycle15, application; and (3) a clarification for the statement "no new GNF2 fuel designs are being introduced in LSCS, Unit 1, Cycle 15," in Section 2.5 of Attachment 5.

4. The LSCS, Unit 1, Cycle 15, is a mixed core with once and twice burned ATRIUM 10 fuel.

Please provide: (1) a detailed description of the methodologies used and procedures applied

-2 to the LSCS, Unit 1, Cycle 15, calculation for the proposed SLMCPR values based on Figure 3, Attachment 5; and (2) justification that the methodologies related to ATRIUM 10 fuel may not be needed in this application because none is listed in Section 1.0, Attachment 5.

5. Please identify the breakdown of the 1Ox1 0 data shown in Attachment 5, Figure 5, by fuel type (Le., GE14, GNF2). because Figure 5 only shows combined data points for the two fuel types. Also, provide: (1) details of the application of Figure 5 data to a mixed core with ATRIUM 10 fuel; and (2) justification that the estimation formula for SLMCPR value is still valid for LSCS, Unit 1, Cycle 15, application.

6. Please clarify that there is no effect of GNF2 bent spacer wing to LSCS, Unit 1, Cycle 15, operation. If there is an adverse impact, please provide an assessment of the impacts on

, operations and fuel thermal performance.

7. Please provide an updated version of power/flow map for Cycle 15 operation including stability Option III features of scram region and controlled entry region for backup stability protection based on the Boiling-Water Reactor Owners Group position stated in NEDO-31960A for SLO and TLO.

'.. ML120110167 NRR-088 OFFICE LPLlII-2/PM LPLlII-2/LA SRXB/BC LPLlII-2/BC LPLlII-2/PM NAME NDiFrancesco SRohrer TUlyses JZimmerman NDiFrancesco DATE 1/10/12 1/19/12 1/10/12 1/19/12 1/ 19/12