ML071060029

RAI, Request for Additional Information Related to Request to Change the Tornado Missile Protection Methodology (TAC Nos. MD2371 & MD2372)

ML071060029
Person / Time
Site:	Byron
Issue date:	04/26/2007
From:	Gratton C NRC/NRR/ADRO/DORL/LPLIII-2
To:	Crane C Exelon Generation Co
Gratton C, NRR/DORL 415-1055
References
TAC MD2371, TAC MD2372
Download: ML071060029 (5)

Text

April 26, 2007 Mr. Christopher M. Crane President and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

BYRON STATION, UNIT NOS. 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION RELATED TO REQUEST TO CHANGE THE TORNADO MISSILE PROTECTION METHODOLOGY (TAC NOS. MD2371 AND MD2372)

Dear Mr. Crane:

By letter to the Nuclear Regulatory Commission (NRC) dated June 16, 2006, as supplemented by letter dated September 14, 2006, Exelon Generation Company, LLC (the licensee),

submitted a license amendment request to approve the use of TORMIS for tornado missile protection analysis at Byron Station, Unit Nos. 1 and 2.

The NRC staff is reviewing the information contained in the letters and has determined that additional information is required to complete the review. The specific information requested is addressed in the enclosure to this letter, a draft of which was sent by facsimile to Mr. David Chrzanowski of your staff on April 12, 2007. During a call on April 24, 2007, Mr. Chrzanowski indicated that a followup call was not needed to clarify the intent of the NRC staff questions.

The NRC staff requests that you respond to the enclosed information request by May 10, 2007.

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 NRCs 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) 415-1055.

Sincerely,

/RA/

Christopher Gratton, Senior Project Manager Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. STN 50-454 and STN 50-455,

Enclosure:

Request for Additional Information cc w/encl: See next page

Mr. Christopher M. Crane April 26, 2007 President and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

BYRON STATION, UNIT NOS. 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION RELATED TO REQUEST TO CHANGE THE TORNADO MISSILE PROTECTION METHODOLOGY (TAC NOS. MD2371 AND MD2372)

Dear Mr. Crane:

By letter to the Nuclear Regulatory Commission (NRC) dated June 16, 2006, as supplemented by letter dated September 14, 2006, Exelon Generation Company, LLC (the licensee),

submitted a license amendment request to approve the use of TORMIS for tornado missile protection analysis at Byron Station, Unit Nos. 1 and 2.

The NRC staff is reviewing the information contained in the letters and has determined that additional information is required to complete the review. The specific information requested is addressed in the enclosure to this letter, a draft of which was sent by facsimile to Mr. David Chrzanowski of your staff on April 12, 2007. During a call on April 24, 2007, Mr. Chrzanowski indicated that a followup call was not needed to clarify the intent of the NRC staff questions.

The NRC staff requests that you respond to the enclosed information request by May 10, 2007.

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 NRCs 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) 415-1055.

Sincerely,

/RA/

Christopher Gratton, Senior Project Manager Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. STN 50-454 and STN 50-455

Enclosure:

Request for Additional Information cc w/encl: See next page DISTRIBUTION:

PUBLIC LPL3-2 R/F RidsNrrDorlLpl3-2 RidsNrrPMCGratton RidsNrrLAEWhitt RidsAcrsAcnwMailCenter RidsOgcRp RidsDeEmcb RidsRgn3MailCenter RidsNrrDorlDpr RidsNrrPMRKuntz TBloomer, EDO Region III RidsNrrDssSbpb ZXi, NRR JTatum, NRR ESmith, NRR ADAMS ACCESSION #: ML071060029 OFFICE LPL3-2/PM LPL3-2/LA DE/EMCB/BC LPL3-2/BC NAME CGratton EWhitt KManoly RGibbs DATE 4/25/07 4/25/07 4/25/07 4/26/07 OFFICIAL RECORD COPY

REQUEST FOR ADDITIONAL INFORMATION BYRON STATION, UNIT NOS. 1 AND 2 DOCKET NOS. STN 50-454 AND STN 50-455 The following questions pertain to your application dated June 16, 2006, as supplemented by your letter dated September 14, 2006:

1. The licensees response to issue 11 in its letter dated September 14, 2006, explains the methodology for conversion of the soil thickness to an equivalent thickness of concrete.

Please provide the minimum soil thickness, as well equivalent concrete thickness, which is adequate to protect the buried piping from tornado generated missiles.

2. The licensees response to issue 11 also indicates that the tornado wind and differential pressure effects on the soil are not accounted for. Since a soil barrier, which cannot be modeled by TORMIS, is not as stable as concrete or steel barriers, the vortex of the tornado can remove some amount of the soil over the area in question. Regulatory Guide 1.76 calls out the design-basis tornado characteristics including pressure drop due to tornados. Please address the possibility that the tornado vortex may remove a certain amount of the soil cover and provide an estimate of the soil thickness that can be removed.

Enclosure

Byron Station, Unit Nos. 1 and 2 cc: Attorney General 500 S. Second Street Regional Administrator, Region III Springfield, IL 62701 U.S. Nuclear Regulatory Commission 2443 Warrenville Road, Suite 210 Plant Manager - Byron Station Lisle, IL 60532-4351 Exelon Generation Company, LLC 4450 N. German Church Road Illinois Emergency Management Agency Byron, IL 61010-9794 Division of Disaster Assistance &

Preparedness Site Vice President - Byron Station 110 East Adams Street Exelon Generation Company, LLC Springfield, IL 62701-1109 4450 N. German Church Road Byron, IL 61010-9794 Document Control Desk - Licensing Exelon Generation Company, LLC Senior Vice President - Operations Support 4300 Winfield Road Exelon Generation Company, LLC Warrenville, IL 60555 4300 Winfield Road Warrenville, IL 60555 Mr. Dwain W. Alexander, Project Manager Westinghouse Electric Corporation Chairman P.O. Box 355 Will County Board of Supervisors Pittsburgh, PA 15230 Will County Board Courthouse Joliet, IL 60434 Howard A. Learner Environmental Law and Policy Director - Licensing and Regulatory Affairs Center of the Midwest Exelon Generation Company, LLC 35 East Wacker Drive 4300 Winfield Road Suite 1300 Warrenville, IL 60555 Chicago, IL 60601-2110 Manager Regulatory Assurance - Byron U.S. Nuclear Regulatory Commission Exelon Generation Company, LLC Byron Resident Inspectors Office 4450 N. German Church Road 4448 North German Church Road Byron, IL 61010-9794 Byron, IL 61010-9750 Associate General Counsel Ms. Lorraine Creek Exelon Generation Company, LLC RR 1, Box 182 4300 Winfield Road Manteno, IL 60950 Warrenville, IL 60555 Chairman, Ogle County Board Vice President - Regulatory Affairs P.O. Box 357 Exelon Generation Company, LLC Oregon, IL 61061 4300 Winfield Road Warrenville, IL 60555 Mrs. Phillip B. Johnson 1907 Stratford Lane Rockford, IL 61107

Byron Station, Unit Nos. 1 and 2 cc:

Manager Licensing - Braidwood, Byron and LaSalle Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Senior Vice President - Midwest Operations Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Mr. Barry Quigley 3512 Louisiana Rockford, IL 61108