ML072330244

RAI Regarding Clarification of the Backup Stability Protection Methodology Evaluation (TAC MD4866 Thru MD4869)

ML072330244
Person / Time
Site:	Dresden, Quad Cities
Issue date:	08/23/2007
From:	Gratton C NRC/NRR/ADRO/DORL/LPLIII-2
To:	Crane C Exelon Generation Co
Gratton C, NRR/DORL 415-1055
References
TAC MD4866, TAC MD4867, TAC MD4868, TAC MD4869
Download: ML072330244 (5)

Text

August 23, 2007 Mr. Christopher M. Crane President and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3, AND QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING CLARIFICATION OF THE BACKUP STABILITY PROTECTION METHODOLOGY EVALUATION (TAC NOS. MD4866 THRU MD4869)

Dear Mr. Crane:

By letter to the Nuclear Regulatory Commission (NRC) dated March 9, 2007, Exelon Generation Company, LLC submitted a request to revise the safety evaluation for the April 4, 2006, amendment to reflect that the immediate scram region is defined as the area in the power-flow map where the decay ratio is > 0.8, and the controlled entry region is defined as the area in the power-flow map where the decay ratio is > 0.8 - cycle uncertainty, for the Dresden Nuclear Power Station, Units 2 and 3, and the Quad Cities Nuclear Power Station, Units 1 and 2.

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. A facsimile of the questions was sent to your staff on July 17, 2007.

During a discussion with Mr. Ken Nicely of your staff on August 16, 2006, Mr. Nicely indicated a clarification conference call was not needed for these questions, and agreed that you would provide a response by September 14, 2007.

C. Crane 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) 415-1470.

Sincerely,

/RA/

Christopher Gratton, Senior Project Manager Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-237 and 50-249; and 50-254 and 50-265

Enclosure:

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

C. Crane 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) 415-1470.

Sincerely,

/RA/

Christopher Gratton, Senior Project Manager Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-237 and 50-249; and 50-254 and 50-265

Enclosure:

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

PUBLIC LPL3-2 R/F RidsNrrDorlLpl3-2 RidsNrrPMCGratton RidsNrrLAEWhitt RidsAcrsAcnwMailCenter RidsOgcRp RidsRgn3MailCenter RidsNrrDorlDpr THuang, NRR RidsNrrPMMThorpe-Kavanaugh ADAMS Accession Number: ML072330244 NRR-088 OFFICE LPL3-2/PM LPL3-2/LA LPL3-2/BC NAME CGratton EWhitt RGibbs DATE 8/20/07 8/20/07 8/23/07 OFFICIAL RECORD COPY

Dresden and Quad Cities Nuclear Power Stations cc:

Site Vice President - Dresden Nuclear Power Station Plant Manager - Quad Cities via e-mail via e-mail Plant Manager - Dresden Nuclear Power Station Regulatory Assurance Manager - Quad Cities via e-mail via e-mail Manager Regulatory Assurance - Dresden Senior Resident Inspector via e-mail Quad Cities Resident Inspectors Office via e-mail U.S. Nuclear Regulatory Commission Dresden Resident Inspectors Office David C. Tubbs 6500 N. Dresden Road via e-mail Morris, IL 60450-9766 Senior Vice President - Midwest Operations Chairman via e-mail Grundy County Board Administration Building Vice President - Law and Regulatory Affairs 1320 Union Street MidAmerican Energy Company Morris, IL 60450 One River Center Place 106 E. Second Street Illinois Emergency Management Agency P.O. Box 4350 Division of Disaster Assistance & Preparedness Davenport, IA 52808 1035 Outer Park Dr Springfield, IL 62704 Chairman Rock Island County Board of Supervisors Document Control Desk - Licensing 1504 3rd Avenue via e-mail Rock Island County Office Bldg.

Rock Island, IL 61201 Senior Vice President Operations Support via e-mail Vice President - Regulatory Affairs via e-mail Director - Licensing and Regulatory Affairs via e-mail Associate General Counsel via e-mail Manager Licensing - Dresden and Quad Cities via e-mail Site Vice President - Quad Cities via e-mail

REQUEST FOR ADDITIONAL INFORMATION DRESDEN NUCLEAR STATION, UNITS 2 AND 3, AND QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 DOCKET NOS. 50-237, 50-249, 50-254, AND 50-265 The NRC staff has reviewed the March 9, 2007, Safety Evaluation revision request and has identified the following questions to be addressed by the licensee in order to complete our evaluation.

A. Please document the procedure used to calculate the cycle uncertainty (cu) term used to define the controlled entry region.

B. Please provide the specific values for cu used for the latest reload in Dresden Nuclear Station, Units 2 and 3 (DNPS), and Quad Cities Nuclear Power Station, Units 1 and 2 (QCNPS).

C. Please describe which approved codes are used to generate the cycle uncertainty.

Include a short description of any benchmark data to support the generic or plant-specific cu values used in DNPS and QCNPS.

Enclosure