ML13004A154

Request for Additional Information Relating to Technical Specification Changes to Safety Limit Minimum Critical Power Ratio for LaSalle County Station, Unit 2 Cycle 15 (ME9796)

ML13004A154
Person / Time
Site:	LaSalle
Issue date:	01/07/2013
From:	Nicholas Difrancesco Plant Licensing Branch III
To:	Pacilio M Exelon Generation Co
Nicholas DiFrancesco, NRR/DORL, 415-1115
References
TAC ME9796
Download: ML13004A154 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 January 7, 2013 Mr. Michael J. Pacilio Senior Vice President Exelon Generation Company, LLC Nuclear President and Chief Nuclear Officer (CNO)

Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

LASALLE COUNTY STATION, UNIT 2 - REQUEST FOR ADDITIONAL INFORMATION RELATING TO TECHNICAL SPECIFICATION CHANGES TO SAFETY LIMIT MINIMUM CRITICAL POWER RATIO FOR LASALLE COUNTY STATION, UNIT 2 CYCLE 15 (TAC NO. ME9769)

Dear Mr. Pacilio:

By letter to the U.S. Nuclear Regulatory Commission (NRC) dated October 11,2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12285A387), Exelon Generation Company, LLC (the licensee) submitted a license amendment request proposing to modify the safety limit minimum critical power ratios contained in Section 2.1 of the technical specifications at LaSalle County Station (LSCS), Unit 2. The proposed changes support upcoming Cycle 15 operation of LSCS, Unit 2.

The NRC staff reviewed 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 3, 2013, it was agreed that you would provide a response by January 22, 2013.

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

M. Pacilio -2 The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for NRC staff review and contribute toward the NRC's goal of efficient and effective use of staff resources.

If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1115.

Sincerely,

~fo~

Nicholas J. DiFrancesco, Project Manager Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-374

Enclosure:

Request for Additional Information cc w/encl: Listserv

REQUEST FOR ADDITIONAL INFORMATION EXELON GENERATION COMPANY, LLC LASALLE COUNTY STATION, UNIT 2 LICENSE AMENDMENT REQUEST REGARDING SAFETY LIMIT MINIMUM CRITICAL POWER RATIO CHANGE DOCKET NO. 50-374 The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the October 11, 2012, Exelon Generation Company, LLC (the licensee) submittal (Agencywide Documents Access and Management System Accession No. IVIL12285A387) regarding changes to the LaSalle County Station (LSCS), Unit 2, Cycle 15, safety limit minimum critical power ratios (SLMCPRs) and has the following questions concerning Attachments 5, 6, and 9 of the submittal:

1. In the license amendment request, Attachment 6 Tables, Request for Additional Information (RAI)-01-1, RAI-01-2 and RAI-01-3 provide a core map to show those bundles that experienced the 0.1 boiling transition criterion of limiting cases for single loop operation (SLO) and two-loop operation (TLO). Please provide: (1) clarification of why the bundle group and bundle type stated in the Fjgure 1, Attachment 5, is different from those listed in Tables RAI-01-1 and RAI-01-2; (2) a description how the data listed in Tables RAI-01-1 and RAI- 01-2 are applied to the final values of the SLMCPR; and (3) the reason why Bundle Group 15 plays such a small role to contribute to 0.1 boiling transition criterion.

2. Core design is an iterative process designed to develop an optimal configuration that meets operational requirements. Please 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 the Cycle 15 analysis with respect to a mixed core application. Also, please provide the rationale that the current LSCS, Unit 2, Cycle 15, core will have an increase of 0.03 and 0.05 SLMCPR value for two recirculation loop operation and SLO, respectively.

3. Global Nuclear Fuel (GNF2) fuel deviates from traditional 1Ox1 0 design through the introduction of a new part length rod configuration, the use of higher linear power, and the use of mixing vanes. The NRC staff considers this to be a new fuel desjgn with regards to the four restrictions identified in the safety evaluation of General Electric Licensing Topical Reports NEDC-32601 P, NEDC-32694, and Amendment 25 to NEDE 24011-P-A. Given that LSCS2, Cycle 15, uses a core loading pattern which includes GNF2 fuel and ATRI UM-1 0, please provide an evaluation of the applicability of the four restrictions stated in NEDC-32601 P, NEDC-32694, and Amendment 25 to NEDE-24011 P-A to ATRIUM-10 fuel since the NRC audit report was only evaluated for GNF-2 not ATRIUM-10 fuel.

Enclosure

-2

4. The LSCS, Unit 2, Cycle 15, is a mixed core with once and twice burned ATRIUM 10 fuel. Please provide: (1) a confirmation that NEDC- 33106P, Revision 4, August 2012, was reviewed and approved by the NRC staff; (2) a detailed description of the difference between GEXL97 Correlation for ATRIUM-10 Fuel, NEDC-33106P-A, Revision 2, June 2004, and GEXL97 Correlation for ATRIUM-10 Fuel, NEDC-33106P-A, Revision 4, August 2012; (3) an analysis on the impact of the SLMCPR value due to the differences identified in Item (2), if any; and (4) the description for the basis and method used to generate nominal uncertainty value for ATRIUM10 and ATRIUM10-XM given in Table 6.

5. Please describe the effect, if any, of a bent spacer wing on GNF2 fuel for LSCS, Unit 2, Cycle 15, operation. If there is an effect, please provide the details of the effect on thermal performance due to GNF2 bent spacer wing.

6. Attachment 9 provides 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 Rector Owners Group position stated in NEDO-31960A for SLO and TLO. Please provide: (1) the decay ratio boundary for Region 2; (2) an explanation why Region 2 covers a very small area in the power/flow map; and (3) any operator actions needed for Region 2.

M. Pacilio -2 The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for NRC staff review and contribute toward the NRC's goal of efficient and effective use of staff resources.

If circumstances result in the need to revise the requested response date, please contact me at (301)415-1115.

Sincerely, 1 RA 1 Nicholas J. DiFrancesco, Project Manager Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-374

Enclosure:

Request for Additional Information cc w/encl: Listserv DISTRIBUTION:

PUBLIC RidsNrrDorlDpr Resource LPL 3-2 RIF RidsRgn3MailCenter Resource RidsNrr DorlLpl3-2 Resource RidsNrrPMLaSalie Resource RidsNrrLASRohrer Resource RidsAcrsAcnw_MailCTR Resource RidsOgcRp Resource ADAMS Accession No.: ML13004A154 "via memorandum OFFICE LPL3-2/PM LPL3-2/LA SRXB/BC" LPL3-2/BC LPL3-2/PM NAME NDiFrancesco SRohrer SSun for MDudek NDiFrancesco CJaskson DATE 1/2/13 1/03 113 12/26/12 1/07/13 1/07 113 OFFICIAL RECORD COpy Enclosure