ML102290088

Draft RAI

ML102290088
Person / Time
Site:	Peach Bottom
Issue date:	08/16/2010
From:	John Hughey Division of Operating Reactor Licensing
To:	Tom Loomis Exelon Corp
Shared Package
ML102290071	List: ML102290088
References
TAC ME3994
Download: ML102290088 (1)

Text

DRAFT REQUEST FOR ADDITIONAL INFORMATION RELATED TO LICENSE AMENDMENT REQUEST FOR TECHNICAL SPECIFICATION CHANGES TO SAFETY LIMIT MINIMUM CRITICAL POWER RATIO VALUES PEACH BOTTOM ATOMIC POWER STATION - UNIT 2 DOCKET NO. 50-277 By letter to the Nuclear Regulatory Commission (NRC) dated May 27, 2010 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML101480555), Exelon Generation Company, LLC, (Exelon) submitted a License Amendment Request (LAR) for Peach Bottom Atomic Power Station (PBAPS), Unit 2. The submittal seeks to revise Technical Specification 2.1.1, Reactor Core SLs [safety limits] to reflect revised Safety Limit Minimum Critical Power Ratio (SLMCPR) values for operating cycle 19.

On July 15, 2010 (ADAMS Accession No. ML102020244), Exelon provided supplemental information in response to NRC requests for additional information (RAI). The NRC staff has reviewed the supplemental information and determined that further additional information, as described below, is needed to complete the review.

RAI-10: For the Cycle 19 Core table provided in response to RAI-01 in the July 15, 2010, supplement, please provide a core map identifying each fuel assemblies including Cycle 17 (thrice-burn) through Cycle 19 (fresh fuel) and identifying assemblies reached 0.1 % boiling transition criterion for the SLMCPR value calculation. Also describe the process for selecting those Cycle 18 fuel assemblies that will be thrice-burned in Cycle 19.

RAI-11: Please describe the impact as well as the contribution of the input items listed in the response to RAI-02 in the July 15, 2010, supplement (such as cycle energy requirements, thermal limit margins, reactivity margins, discharge exposure limitations and other limits, desired control rod patterns, and channel distortion) on the final core loading pattern for Cycle 19.

In general, the reference core loading pattern is expected be a final core loading pattern unless a leaking fuel rod is present. SLMCPR will be determined based on the proposed final core loading pattern with the planned control rod control sequence. The hot bundles will be identified during this SLMCPR calculation process, which will be an important parameter applied to stability setpoint, and transient analysis for the Operating Limit (OL)MCPR. Therefore, the process used to generate a final core loading pattern plays an important role in the SLMCPR calculations.

RAI-12: Provide the information that documents the mechanisms that push the SLMCPR increase into the higher range of expectations as described in RAI-05 in the July 15, 2010, supplement.

RAI-13: Identify the specific GNF-2 data points associated with the revised Figure 5 provided in the response to RAI-08 in the July 15, 2010, supplement.

Enclosure