ML061380518

Exemption from the Requirements of 10 CFR Part 50, Section 50.44, Section 50.46, and Appendix K to Part 50

ML061380518
Person / Time
Site:	Byron
Issue date:	06/30/2006
From:	Robert Kuntz Plant Licensing Branch III-2
To:	Crane C Exelon Generation Co
Kuntz, Robert , NRR/DLPM, 415-3733
References
TAC MC8517, TAC MC8518
Download: ML061380518 (11)

Text

June 30, 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 - EXEMPTION FROM THEREQUIREMENTS OF 10 CFR 50.44, 10 CFR 50.46, AND 10 CFR PART 50, APPENDIX K (TAC NOS. MC8517 AND MC8518)

Dear Mr. Crane:

The Commission has approved the enclosed exemption from specific requirements of Title 10 of the Code of Federal Regulations (10 CFR) Section 50.44, 10 CFR 50.46 and 10 CFRPart 50, Appendix K, for Byron Station, Unit Nos. 1 and 2. This action is in response to your letter of September 23, 2005, which submitted a request for an exemption from the aforementioned regulations. The exemption allows the use of up to four lead test assemblies containing fuel rods with AXIOM TM cladding.A copy of the exemption has been forwarded to the Office of the Federal Register forpublication. Sincerely,/RA/Robert F. Kuntz, Project ManagerPlant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor RegulationDocket Nos. STN 50-454 and STN 50-455

Enclosure:

Exemptioncc w/encl: See next page Mr. Christopher M. Crane, PresidentJune 30, 2006 and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

BYRON STATION, UNIT NOS. 1 AND 2 - EXEMPTION FROM THEREQUIREMENTS OF 10 CFR 50.44, 10 CFR 50.46, AND 10 CFR PART 50, APPENDIX K (TAC NOS. MC8517 AND MC8518)

Dear Mr. Crane:

The Commission has approved the enclosed exemption from specific requirements of Title 10 of the Code of Federal Regulations (10 CFR) Section 50.44, 10 CFR 50.46 and 10 CFRPart 50, Appendix K, for Byron Station, Unit Nos. 1 and 2. This action is in response to your letter of September 23, 2005, which submitted a request for an exemption from the aforementioned regulations. The exemption allows the use of up to four lead test assemblies containing fuel rods with AXIOM TM cladding.A copy of the exemption has been forwarded to the Office of the Federal Register forpublication. Sincerely,/RA/Robert F. Kuntz, Project Manager Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor RegulationDocket Nos. STN 50-454 and STN 50-455

Enclosure:

Exemptioncc w/encl: See next page DISTRIBUTION

PUBLICRidsNrrDssSpwbLPL3-2 R/FRidsOgcRp RidsNrrDorlLpl3-2RidsAcrsAcnwMailCenterRidsNrrPMRKuntzRidsNrrDorl RidsNrrLADClarkeJ. Dixon-Herrity, EDO Rgn III RidsRgn3MailCenterRidsNrrDorlDprADAMS Accession Number: ML061380518*NLO w/commentsOFFICELPL3-2/PMLPL3-2/LASPWB/BCOGC*LPL3-2/BCDORL/DDNAMERKuntz:mwDClarkeJNakoskiAHodgdonDCollinsCH aneyDATE6/12/066/12/066/15/066/26/066/28/066/30/06OFFICIAL RECORD COPY Byron Station Units 1 and 2 cc:

Regional Administrator, Region IIIU.S. Nuclear Regulatory Commission Suite 210 2443 Warrenville RoadLisle, IL 60532-4351Illinois Emergency Management Agency Division of Disaster Assistance &

Preparedness 110 East Adams Street Springfield, IL 62701-1109Document Control Desk - LicensingExelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555Mr. Dwain W. Alexander, Project ManagerWestinghouse Electric Company Post Office Box 355 Pittsburgh, PA 15230Joseph Gallo Gallo & Ross 1025 Connecticut Ave., NW, Suite 1014 Washington, DC 20036Howard A. LearnerEnvironmental Law and Policy Center of the Midwest 35 East Wacker Drive Suite 1300 Chicago, IL 60601-2110U.S. Nuclear Regulatory CommissionByron Resident Inspector's Office 4448 North German Church Road Byron, IL 61010-9750Ms. 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 62706Byron Station Plant ManagerExelon 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 61010-9794Senior Vice President of OperationsExelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555ChairmanWill County Board of Supervisors302 North Chicago Street Will County Board CourthouseJoliet, Illinois 60434 Byron Station Units 1 and 2- 2 -Director - Licensing and Regulatory AffairsExelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555Regulatory Assurance Manager - 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 - Licensing and Regulatory Affairs Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555Manager Licensing - Braidwood and ByronExelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 7590-01-PUNITED STATES OF AMERICANUCLEAR REGULATORY COMMISSIONEXELON GENERATION COMPANY, LLCBYRON STATION, UNIT NOS. 1 AND 2DOCKET NOS. STN 50-454 AND STN 50-455EXEMPTION

1.0BACKGROUND

The Exelon Generation Company, LLC (Exelon, licensee) is the holder of FacilityOperating License Nos. NPF-37 and NPF-66 which authorize operation of the Byron StationUnit 1 and Unit 2, respectively. The licenses provide, among other things, that the facility issubject to all rules, regulations, and orders of the Nuclear Regulatory Commission (NRC,Commission) now or hereafter in effect.The facility consists of two pressurized-water reactors located in Ogle County, Illinois.2.0REQUEST/ACTIONPursuant to Title 10 of the Code of Federal Regulations (10 CFR) Section 50.12,"Specific exemptions," Exelon has requested an exemption from 10 CFR 50.44, "Combustible gas control system for nuclear power reactors"; 10 CFR 50.46, "Acceptance criteria for emergency core cooling systems [ECCS] for light-water nuclear power reactors"; and Appendix K to 10 CFR Part 50, "ECCS Evaluation Models." The regulation at 10 CFR 50.44 specifies requirements for the control of hydrogen gas generated after a postulated loss-of-coolant accident (LOCA) for reactors fueled with zirconium cladding. Section 50.46 contains acceptance criteria for ECCS for reactors fueled with zircaloy or ZIRLO TM cladding. Appendix K to 10 CFR Part 50 requires that the Baker-Just equation be used to predict the rates of energyrelease, hydrogen concentration, and cladding oxidation from the metal-water reaction. The exemption request relates solely to the specific types of cladding material specifiedin these regulations. As written, the regulations presume the use of zircaloy or ZIRLO TM fuelrod cladding. Thus, an exemption from the requirements of 10 CFR 50.44, 10 CFR 50.46, andAppendix K to 10 CFR Part 50, is needed to irradiate lead test assemblies (LTAs) comprised of the AXIOM TM developmental clad alloys at Byron Station, Unit Nos. 1 and 2.3.0DISCUSSION3.1Material Design3.1.1Fuel Material DesignIn order to meet future demands of the nuclear industry, Westinghouse is evaluating thein-reactor performance of several developmental alloys. The licensee states that the material properties and mechanical performance of the advanced cladding alloys are expected to be similar to Zircaloy-4 and ZIRLO TM, and that any difference in phase transition temperatures andmechanical strength will be considered in the LTA fuel rod design evaluation. Further,preliminary autoclave testing indicates that the advanced alloys exhibit acceptable corrosion resistance. This is consistent with the NRC staff's expectation that unirradiated properties ofany advanced cladding alloy will be accounted for in the LTA fuel rod design evaluation.The licensee's September 23, 2005, letter stated:The current licensed fuel performance code predictions for the developmentalcladding will be compared to post-irradiation examination data at Byron Station. If significantly adverse observations are found relative to predictions, the adverse rod(s) will either be removed and the fuel assembly will be reconstituted withsuitable replacement rods, or the entire fuel assembly will be removed from the following fuel cycle(s) until deviations are understood and addressed.Where appropriate, concurrent data obtained from other LTA programs for thesame developmental claddings will be factored into the assessment of the LTAsat Byron Station. Specifically, before the assemblies are reinserted, all available information will be reviewed to ensure existing design assumptions remain valid. Based upon the limited number of advanced alloy fuel rods placed in non-limiting corelocations, specifically accounting for significant deviations in unirradiated material and mechanical properties, and an LTA post-irradiation examination program aimed at qualifying model predictions and understanding deviations, the NRC staff finds the LTA mechanicaldesign acceptable for Byron Station Unit Nos. 1 and 2.

3.1.2Core Physics and Non-LOCA AnalysisThe exemption request relates solely to the specific types of cladding material specifiedin the regulations. No new or altered design limits for purposes of 10 CFR Part 50, Appendix A, General Design Criterion 10, "Reactor design," need to be applied or are required for this program.The standard reload methodologies will be applied to the advanced cladding alloys. Nuclear design evaluations will assure that LTAs will be placed in non-limiting core locations. As such, additional thermal margin to design limits will be maintained between LTA fuel rodsand the hot rod evaluated in safety analyses. Thermal-hydraulic and non-LOCA evaluations willconfirm that the LTAs are bounded by the current analysis of record.Based upon testing to date it is not anticipated that any of the advanced cladding fuelrods would fail during normal operation. However, if any failures occurred, their effects would be well within technical specification limits for doses and, in all cases, core coolable geometry would be maintained. The NRC staff agrees that the placement of a limited number ofadvanced alloy fuel rods in non-limiting locations would not challenge reported dose consequences nor core coolability.Based upon the limited number of advanced alloy fuel rods placed in non-limiting corelocations, the use of approved models and methods, and expected material performance, the NRC staff finds that the irradiation of up to four LTAs at the Byron Station will not result in unsafe operation nor violation of specified acceptable fuel design limits. Furthermore, in the event of a design-basis accident, these LTAs will not promote consequences beyond thosecurrently analyzed.

3.2Regulatory EvaluationPursuant to 10 CFR 50.12, the Commission may, upon application by any interestedperson or upon its own initiative, grant exemptions from the requirements of 10 CFR Part 50 when (1) the exemptions are authorized by law, will not present an undue risk to public health orsafety, and are consistent with the common defense and security; and (2) when special circumstances are present.

3.2.110 CFR 50.44The underlying purpose of 10 CFR 50.44 is to assure that means are provided for thecontrol of hydrogen gas that may be generated following a LOCA. The licensee has provided a means for controlling hydrogen gas and has previously considered the potential for hydrogengas generation stemming from a metal-water reaction. Based upon the material composition of these alloys, which is similar to other licensed zirconium alloys, the high temperature metal-water reaction rates are expected to be similar. Due to the limited number and anticipated performance of the advanced cladding fuel rods, the previous calculations of hydrogen production resulting from a metal-water reaction will not be significantly changed. As such, thelimitations of 10 CFR 50.44 related to cladding material is not necessary for the licensee to achieve the underlying purpose of the rule in these circumstances.

3.2.210 CFR 50.46The underlying purpose of 10 CFR 50.46 is to establish acceptance criteria for ECCSperformance in response to LOCAs. Due to the limited number of advanced alloy fuel rods, any change in the post-LOCA ductility characteristics of the advanced alloy fuel rods (relative to the 2200 F peak cladding temperature and 17 percent effective cladding reacted) would notchallenge core coolable geometry. Westinghouse performs cycle-specific reload evaluations to assure that 10 CFR 50.46 acceptance criteria are satisfied and will include the LTAs in suchanalyses. Thus, the limitations of 10 CFR 50.46 related to cladding material are not necessary for the licensee to achieve the underlying purpose of the rule in these circumstances.

3.2.310 CFR 50, Appendix KParagraph I.A.5 of Appendix K to 10 CFR Part 50 states that the rates of energy,hydrogen concentration, and cladding oxidation from the metal-water reaction shall be calculated using the Baker-Just equation. Since the Baker-Just equation presumes the use ofzircaloy clad fuel, strict application of the rule would not permit use of the equation for the advanced cladding alloys for determining acceptable fuel performance. Based upon the material composition of these alloys, which is similar to other licensed zirconium alloys, the high temperature metal-water reaction rates are expected to be similar. Because of the limited number of AXIOM TM clad fuel rods and the similarity in material composition to other advancedcladding fuel rods, the NRC staff concludes that the application of the Baker-Just equation inthese conditions is acceptable. Thus, application of 10 CFR Part 50 Appendix K, Paragraph I.A.5 is not necessary for the licensee to achieve the underlying purpose of the rule in these circumstances.

3.2.4Special CircumstancesIn summary, the NRC staff reviewed the licensee's request of proposed exemption toallow up to four LTAs containing fuel rods with AXIOM TM cladding. Based on the NRC staff'sevaluation, as set forth above, the NRC staff considers that granting the proposed exemptionwill not defeat the underlying purpose of 10 CFR 50.46, 10 CFR 50.44, or Appendix K to10 CFR Part 50. Accordingly, special circumstances, are present pursuant to 10 CFR 50.12(a)(2)(ii).

3.2.5Other Standards in 10 CFR 50.12 The NRC staff examined the rest of the licensee's rationale to support the exemptionrequest, and concluded that the use of AXIOM TM would satisfy 10 CFR 50.12(a) as follows: 1)The requested exemption is authorized by law:No law precludes the activities covered by this exemption request. The Commission,based on technical reasons set forth in rulemaking records, specified the specific cladding materials identified in 10 CFR 50.44, 10 CFR 50.46, and 10 CFR Part 50, Appendix K. Cladding materials are not specified by statute.

2)The requested exemption does not present an undue risk to the public health and safety as stated in the licensee's exemption request:The LTA safety evaluation will ensure that the acceptance criteria of 10 CFR50.46, 10 CFR 50.44, and 10 CFR 50 Appendix K are met following insertion of the assemblies containing AXIOMTM material. Fuel assemblies using AXIOM TMcladding will be evaluated using NRC-approved analytical methods and willaddress the changes in the cladding material properties. The safety analysis for Byron Station Units 1 and 2 is supported by the applicable Technical Specifications. The Byron Station Units 1 and 2 reload cores containing AXIOM TM cladding will continue to be operated in accordance with the operatinglimits specified in the Technical Specifications. LTAs using AXIOM TM claddingwill be placed in non-limiting core locations. Therefore, this exemption will notpose an undue risk to public health and safety.The NRC staff has evaluated these considerations as set forth in Section 3.1 of thisexemption. For the reasons set forth in that section, the NRC staff concludes that AXIOM TM may be used as a cladding material for no more than four LTAs to be placed in non-limiting core locations during Byron's next refueling outage, and that an exemption from the requirements of 10 CFR 50.44, 10 CFR 50.46, and 10 CFR Part 50, Appendix K does not posean undue risk to the public health and safety.

3)The requested exemption will not endanger the common defense and security: The common defense and security are not affected and, therefore, not endangered bythis exemption.

4.0CONCLUSION

Accordingly, the Commission has determined that, pursuant to 10 CFR 50.12(a), theexemption is authorized by law, will not present an undue risk to the public health and safety,and is consistent with the common defense and security. Also, special circumstances are present. Therefore, the Commission hereby grants Exelon an exemption from the requirementsof 10 CFR 50.44, 10 CFR 50.46 and 10 CFR Part 50, Appendix K, for Byron Station, Unit Nos. 1 and 2.Pursuant to 10 CFR 51.32, the Commission has determined that the granting of thisexemption will not have a significant effect on the quality of the human environment (71 FR 32144).

This exemption is effective upon issuance.Dated at Rockville, Maryland, this 30th day of June 2006.FOR THE NUCLEAR REGULATORY COMMISSION/RA/Catherine Haney, DirectorDivision of Operating Reactor Licensing Office of Nuclear Reactor Regulation