ML061460284

and Braidwood Station, Unit Nos. 1 and 2 - Environmental Assessment and Finding of No Significant Impact Related to Exemption from Requirements of 10 CFR 50.60(a) and 10 CFR Part 50, Appendix G

ML061460284
Person / Time
Site:	Byron, Braidwood
Issue date:	09/22/2006
From:	Kuntz R F NRC/NRR/ADRO/DORL/LPLIII-2
To:	Crane C M Exelon Generation Co
Tom Wengert X4037
References
TAC MC8697, TAC MC8698, TAC MC8699, TAC MC8700
Download: ML061460284 (10)

Text

September 22, 2006Mr. 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, AND BRAIDWOOD STATION,UNIT NOS. 1 AND 2 - ENVIRONMENTAL ASSESSMENT AND FINDING OF NO SIGNIFICANT IMPACT RELATED TO EXEMPTION FROM REQUIREMENTS OF 10 CFR 50.60(a) AND 10 CFR PART 50, APPENDIX G (TAC NOS. MC8697, MC8698, MC8699, AND MC8700)

Dear Mr. Crane:

Enclosed is a copy of the Environmental Assessment and Finding of No Significant Impactrelated to your application for exemption dated October 3, 2005. The proposed exemptionwould allow the use of WCAP-16143, "Reactor Vessel Closure Head /Vessel Flange Requirements Evaluation for Byron/Braidwood Units 1 and 2," dated November 2003 in calculating the reactor pressure vessel pressure-temperature limits for Byron Station, Unit Nos. 1 and 2, and Braidwood Station, Unit Nos. 1 and 2, in lieu of Title 10 of the Code ofFederal Regulations (10 CFR), Part 50, Appendix G, "Fracture Toughness Requirements,"paragraph IV.A.2.c as required by 10 CFR 50.60(a).The assessment is being forwarded to the Office of the Federal Register for publication.Sincerely,/RA/Robert F. Kuntz, Project ManagerPlant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor RegulationDocket Nos. 50-454, 50-455, 50-456, and 50-457

Enclosure:

Environmental Assessmentcc w/encl: See next page September 22, 2006Mr. 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, AND BRAIDWOOD STATION,UNIT NOS. 1 AND 2 - ENVIRONMENTAL ASSESSMENT AND FINDING OF NO SIGNIFICANT IMPACT RELATED TO EXEMPTION FROM REQUIREMENTS OF 10 CFR 50.60(a) AND 10 CFR PART 50, APPENDIX G (TAC NOS. MC8697, MC8698, MC8699, AND MC8700)

Dear Mr. Crane:

Enclosed is a copy of the Environmental Assessment and Finding of No Significant Impactrelated to your application for exemption dated October 3, 2005. The proposed exemptionwould allow the use of WCAP-16143, "Reactor Vessel Closure Head /Vessel Flange Requirements Evaluation for Byron/Braidwood Units 1 and 2," dated November 2003 in calculating the reactor pressure vessel pressure-temperature limits for Byron Station, Unit Nos. 1 and 2, and Braidwood Station, Unit Nos. 1 and 2, in lieu of Title 10 of the Code ofFederal Regulations (10 CFR), Part 50, Appendix G, "Fracture Toughness Requirements,"paragraph IV.A.2.c as required by 10 CFR 50.60(a).The assessment is being forwarded to the Office of the Federal Register for publication.Sincerely,/RA/Robert F. Kuntz, Project Manager Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor RegulationDocket Nos. 50-454, 50-455, 50-456, and 50-457

Enclosure:

Environmental Assessment cc w/encl: See next pageDISTRIBUTION

PUBLICLPL3-2 R/F RSkokowski, RIIITWengert RidsOgcRpRidsNrrLADClarkeRidsNrrDrlRebbRidsAcrsAcnwMailCenter RidsNrrPMRKuntzRidsNrrDorlLpl3-2RidsNrrDciCvibRHardiesADAMS Accession Number: ML061460284OFFICEPM:LPL3-2LA:LPL3-2DLR/REBBDCI/CVIBOGCBC:LPL3-2NAMERKuntzDClarkeRFranovichMMitchellMLemoncelliDCollinsDATE8/10/068/10/067/3/067/6/068/16/069/22/06OFFICIAL RECORD COPY Byron/Braidwood Stations cc:

Dwain W. Alexander, Project ManagerWestinghouse Electric Corporation Energy Systems Business Unit Post Office Box 355 Pittsburgh, PA 15230-0355Howard A. LearnerEnvironmental Law and Policy Center of the Midwest 35 East Wacker Dr., Suite 1300 Chicago, IL 60601-2110U.S. Nuclear Regulatory CommissionByron Resident Inspectors Office 4448 N. German Church Road Byron, IL 61010-9750Regional Administrator, Region IIIU.S. Nuclear Regulatory Commission Suite 210 2443 Warrenville RoadLisle, IL 60532-4351Ms. Lorraine CreekRR 1, Box 182 Manteno, IL 60950Chairman, Ogle County BoardPost Office Box 357 Oregon, IL 61061Mrs. Phillip B. Johnson1907 Stratford Lane Rockford, IL 61107Attorney General500 S. Second Street Springfield, IL 62701Illinois Emergency Management Agency Division of Disaster Assistance &

Preparedness 110 East Adams Street Springfield, IL 62701-1109Plant Manager - Byron StationExelon Generation Company, LLC 4450 N. German Church Road Byron, IL 61010-9794Site Vice President - ByronExelon Generation Company, LLC 4450 N. German Church Road Byron, IL 61010-9794U.S. Nuclear Regulatory CommissionBraidwood Resident Inspectors Office 35100 S. Rt. 53, Suite 79 Braceville, IL 60407County Executive Will County Office Building 302 N. Chicago Street Joliet, IL 60432Plant Manager - Braidwood Station Exelon Generation Company, LLC 35100 S. Rt. 53, Suite 84 Braceville, IL 60407-9619Ms. Bridget Little RoremAppleseed Coordinator 117 N. Linden Street Essex, IL 60935Document Control Desk - LicensingExelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555Site Vice President - BraidwoodExelon Generation Company, LLC 35100 S. Rt. 53, Suite 84 Braceville, IL 60407-9619Senior Vice President - Operations SupportExelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Byron/Braidwood Stations Director - Licensing and Regulatory Affairs Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555Manager Regulatory Assurance - BraidwoodExelon Generation Company, LLC 35100 S. Rt. 53, Suite 84 Braceville, IL 60407-9619Manager Regulatory Assurance - ByronExelon Generation Company, LLC 4450 N. German Church Road Byron, IL 61010-9794Assistant General CounselExelon Generation Company, LLC 200 Exelon Way Kennett Square, PA 19348Vice President - Regulatory & Legal AffairsExelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555Manager Licensing - Braidwood/ByronExelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555Senior Vice President - Midwest OperationsExelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 7590-01-PUNITED STATES NUCLEAR REGULATORY COMMISSIONEXELON GENERATION COMPANY, LLCDOCKET NOS. STN 50-454, STN 50-455, STN 50-456 AND STN 50-457BYRON STATION, UNIT NOS. 1 AND 2BRAIDWOOD STATION, UNIT NOS. 1 AND 2ENVIRONMENTAL ASSESSMENT AND FINDING OFNO SIGNIFICANT IMPACTThe U.S. Nuclear Regulatory Commission (NRC) is considering issuance of an exemption from the requirements of Title 10 of the Code of Federal Regulations (10 CFR)Part 50, Section 50.60(a), for Facility Operating License Nos. NPF-37, NPF-66, NPF-72 and NPF-77, issued to Exelon Generation Company, LLC (the licensee), for operation of the Byron Station, Unit Nos. 1 and 2 (Byron), and Braidwood Station, Unit Nos. 1 and 2 (Braidwood),

located in Ogle County, Illinois and W ill County, Illinois, respectively. Therefore, as required by10 CFR 51.21, the NRC is issuing this environmental assessment and finding of no significantimpact.

ENVIRONMENTAL ASSESSMENTIdentification of the Proposed Action

The proposed action would allow the use of the methods described in WestinghouseCommercial Atomic Power Report (WCAP)-16143, "Reactor Vessel Closure Head/Vessel Flange Requirements Evaluation for Byron/Braidwood Units 1 and 2," dated November 2003, incalculating the reactor pressure vessel (RPV) pressure-temperature (P-T) limits for Byron and Braidwood, in lieu of 10 CFR Part 50, Appendix G, "Fracture Toughness Requirements,"

paragraph IV.A.2.c as required by 10 CFR 50.60(a). The proposed action is in accordance with the licensee's application for exemptiondated October 3, 2005.

The Need for the Proposed Action

The proposed action is needed because utilization of WCAP-16143 will enhance overallplant safety by widening the P-T operating window, especially in the region of low temperature operations. The primary two safety benefits that would be realized are the following: (1) a reduction in the potential challenges to the low-temperature overpressure protection systemand resultant inadvertent opening of a power operated relief valve, and (2) a reduction in the risk of damaging the reactor coolant pump seals due to pump operation under conditions in which it is difficult to maintain adequate seal differential pressure to ensure proper pump operation.Appendix G to 10 CFR Part 50 contains requirements for P-T limits for the primarysystem and requirements for metal temperature of the closure head flange and vessel flangeregions. The P-T limits are to be determined using the methodology of American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI,Appendix G, but the flange temperature requirements are specified in 10 CFR Part 50, Appendix G. This regulation (Table 1 of 10 CFR Part 50, Appendix G) states that the metal temperature at the closure flange regions must exceed the material unirradiated nil-ductilitytransition reference temperature (RTNDT) by at least 120 °F for normal operation when thepressure exceeds 20 percent of the pre-service hydrostatic test pressure.This requirement was originally based on concerns about the fracture margin in theclosure flange region. During the boltup process, outside surface stresses in this region typically reach over 70 percent of the steady state stress, without being at steady state temperature. The margin of 120 °F and the pressure limitation of 20 percent of hydrostatic pressure were developed in the mid-1970s using the ASME Code lower bound crack arrest/dynamic test fracture toughness (K Ia) to ensure that appropriate margins would bemaintained.Improved knowledge of fracture toughness and other issues that affect the integrity ofthe reactor vessel have led to the recent change to allow the use of the ASME Code lower bound static crack initiation fracture toughness (K Ic) in the development of P-T curves, ascontained in ASME Code Case N-640, "Alternative Reference Fracture Toughness for Development of P-T Limit Curves for Section XI, Division 1." ASME Code Case N-640 has been approved for use without conditions by the NRC staff in Regulatory Guide 1.147,"Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1," published inAugust 2005. However, P-T limit curves can still produce operational constraints by limiting theoperational range available to the operator during heatup and cooldown of the plant, especially when considering requirements in the closure head flange and the vessel flange regions.

Implementing the P-T curves that use K Ic material fracture toughness without exempting theflange requirement of 10 CFR Part 50, Appendix G, would place a restricted operating window in the temperature range associated with the closure head flange and reactor vessel flange, without a commensurate increase in plant safety.

Environmental Impacts of the Proposed Action

The NRC has completed its evaluation of the proposed action and concludes that themore conservative minimum temperature requirements related to footnote (2) to Table 1 of 10 CFR Part 50, Appendix G are not necessary to meet the underlying intent of 10 CFR Part 50 Appendix G, to protect the Byron and Braidwood RPVs from brittle fracture during normal operation under both core critical and core non-critical conditions and RPV hydrostatic and leak test conditions. The details of the NRC staff's safety evaluation will be provided in the exemption thatwill be issued as part of the letter to the licensee approving the exemption to the regulation.The proposed action will not significantly increase the pr obability or consequences ofaccidents. No changes are being made in the types of effluents that may be released off site.

There is no significant increase in the amount of any effluent released off site. There is no significant increase in occupational or public radiation exposure. Therefore, there are nosignificant radiological environmental impacts associated with the proposed action.With regard to potential non-radiological impacts, the proposed action does not have apotential to affect any historic sites. It does not affect non-radiological plant effluents and has no other environmental impact. Therefore, there are no significant non-radiological environmental impacts associated with the proposed action.Accordingly, the NRC concludes that there are no significant environmental impactsassociated with the proposed action.

Environmental Impacts of the Alternatives to the Proposed Action

As an alternative to the proposed action, the NRC staff considered denial of theproposed action (i.e., the "no-action" alternative). Denial of the application would result in no change in current environmental impacts. The environmental impacts of the proposed action and the alternative action are similar.

Alternative Use of Resources

The action does not involve the use of any different resources than those previouslyconsidered in the Final Environmental Statement for the Byron and Braidwood stations,NUREG-0848 dated April 1982, and NUREG-1026 dated June 1984, respectively.Agencies and Persons Consulted

In accordance with its stated policy, on June 19, 2006, the NRC staff consulted with theIllinois State official, Mr. Frank Niziolek of the Illinois Emergency Management Agency, regarding the environmental impact of the proposed action. The State official had nocomments.

FINDING OF NO SIGNIFICANT IMPACTOn the basis of the environmental assessment, the NRC concludes that the proposedaction will not have a significant effect on the quality of the human environment. Accordingly,the NRC has determined not to prepare an environmental impact statement for the proposedaction.For further details with respect to the proposed action, see the licensee's letter datedOctober 3, 2005. Documents may be examined, and/or copied for a fee, at the NRC's PublicDocument Room (PDR), located at One White Flint North, Public File Area O1 F21, 11555 Rockville Pike (first floor), Rockville, Maryland. Publicly available records will be accessibleelectronically from the Agencywide Documents Access and Management System (ADAMS)

Public Electronic Reading Room on the Internet at the NRC Web site,http://www.nrc.gov/reading-rm/adams.html. Persons who do not have access to ADAMS orwho encounter problems in accessing the documents located in ADAMS should contact the NRC PDR Reference staff by telephone at 1-800-397-4209 or 301-415-4737, or send an e-mail to pdr@nrc.gov. Dated at Rockville, Maryland, this 22nd day of September 2006.FOR THE NUCLEAR REGULATORY COMMISSION/RA/Robert F. Kuntz, Project ManagerPlant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation