RS-07-107, Withdrawal of License Amendment Request Related to the Application of the TORMIS Methodology

Withdrawal of License Amendment Request Related to the Application of the TORMIS Methodology

ML072050345
Person / Time
Site:	Byron
Issue date:	07/24/2007
From:	Benyak D Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-07-107, TAC MD2371, TAC MD2372
Download: ML072050345 (2)

Text

Exe~ I o nM Exelon Generation 4300 WintSeld Road www.exeloncoip .corn Nuclear Wart enville, I L 60555 10 CFR 50 .90 RS-07-107 July 24, 2007 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Byron Station, Units 1 and 2 Facility Operating License Nos . NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455

Subject:

Withdrawal of License Amendment Request Related to the Application of the TORMIS Methodology References : (1) Letter from K. R. Jury (Exelon Generation Corporation, LLC) to U .S. NRC, "Request for License Amendment Related to the Application of the TORMIS Methodology," dated June 16, 2006 (2) Letter from C . Gratton (U . S. NRC) to C . M. Crane (Exelon Generation Corporation, LLC), "Byron Station, Unit Nos. 1 and 2 - Request for Additional Information Related to Request to Change the Tornado Protection Methodology (TAC Nos. MD2371 and MD2372)," dated April 26, 2007 In the Reference 1 submittal, Exelon Generation Company, LLC (EGC) requested an amendment to Facility Operating License Nos . NPF-37 and NPF-66 for Byron Station, Units 1 and 2, respectively to revise the Byron Station Updated Final Safety Analysis Report (UFSAR) .

This revision would incorporate changes to the requirements for physical protection from tornado generated missiles for certain systems and components and, in addition, would specify the methodology used to determine which systems and components require physical protection from tornado generated missiles . This methodology is a probabilistic based missile strike analysis and is based on the Electric Power Research Institute (EPRI) Topical Report EPRI NP-2005, "Tornado Missile Risk Evaluation Methodology." Reference 2, requested additional information regarding the Reference 1 TORMIS submittal .

EGC has determined that in order to resolve the open issues regarding the Byron Station application of the TORMIS methodology, a reanalysis using revised computer model inputs will be required .

U. S. Nuclear Regulatory Commission Page 2 July 24, 2007 Since this reanalysis is expected to modify the technical information as well as the number of affected systems and components provided in the original Reference 1 submittal, EGC is requesting that the Reference 1 license amendment request be withdrawn . EGC plans on providing a revised TORMIS-based license amendment submittal after completion of the reanalysis.

EGC is providing the State of Illinois with a copy of this letter to the designated State Official .

There are no Regulatory Commitments contained in this response .

If you have any questions about this letter, please contact Mr. David Chrzanowski at (630) 657-2816 .

Respectfully, Darin M. Benyak Director - Licensing and Regulatory Affairs