ML20153D120
| ML20153D120 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 09/15/1998 |
| From: | Jeffery Wood CENTERIOR ENERGY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 2553, NUDOCS 9809240318 | |
| Download: ML20153D120 (6) | |
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Davis-Besse Nuc! ar Power Station E EE 5501 North State Route x m
Oak Harbor. Ohio 43449 9760
.lohn K. Wood 419-249-2300 VicePresidernt Nuclear Fax: 419-321-8337 License Number NPF-3 Docket Number 50-346 Serial Number 2553 September 15, 1998 United Str.te., Nuclear Regulatory Commission Document Control Desk Washington, D. C. 20555-0001
Subject:
Request for Exemption from 10 CFR 50.46,10 CFR 50.44, and 10 CFR 50 Appendix K, Regarding the Proposed Use of the "M5" Advanced Alloy for Fuel Rod Cladding Ladies and Gentlemen:
This letter transmits Toledo Edison's request for an exemption from Title 10 of the Code of Federal Regulations (CFR), Section 50.46," Acceptance Criteria for Emergency Core Cooling Systems for Light-Water Nuclear Power Reactors," Section 50.44," Standards for Combustible Gas Control System in Light-Water-Cooled Power Reacto s," and associated Appendix K, "ECCS Evaluation Models." These 10 CFR Part 50 references each currently presume the use of Zircaloy or ZIRLO fuel rod cladJing.
As described in a March 3,1998, Toledo Edison (TE) letter (TE Serial Number 2516), pending approval of this exemption request and an associated license amendment application, TE intends to use the Framatome Cogema Fuels (FCF) "M5" advanced alloy for fuel rod cladding. The M5 alloy is a proprietary zirconium-based alloy. Since the chemical composition of the M5 alloy differs from the specifications for Zircaloy or ZIRLO, a plant-specific exemption is required to p
allow the use of the M5 alloy as a cladding material at the DBNPS.
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The above-mentioned license amendment application, License Amendment Request (LAR) 98-0006, was transmitted to the NRC by separate letter (TE Serial Number 2552) dated September 8,1998.
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Docket Number 50 346 License Number NPF-3 i
Serial Number 2553 Page 2 l
Information supporting this exemption request is contained in the attachment. Toledo Edison has concluded that for the reasons specified in the attachment, special circumstances as defined in 10 CFR 50.12 exist and that the granting of the requested exemption will not present an undue risk to the health and safety of the public and is consistent with the common defense and securi y.
t Toledo Edison intends to use the M5 alloy in DBNPS operating Cycle 13. Fuel assemblies for Cycle 13 are presently scheduled to be delivered to the DBNPS in February of 2000 and loaded into the core in April of 2000. In order to allow for completion of the design and analysis activities associated with this schedule, Toledo Edison requests that the NRC issue the proposed
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exemption by April 1,1999, in conjunction with issuance of the associated license amendment.
Should you have any questions or require additional information, please contact Mr. James L. Freels, Manager - Regulatory Affairs, at (419) 321-8466.
Very truly yours, l
~ Killaj Attachment cc:
J. L. Caldwell, Acting Regional Administrator, NRC Region III S. J. Campbell, DB-1 NRC Senior Resident Inspector A. G. Hansen, DB-1 NRC/NRR Project Manager Utility Radiological Safety Board l.
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Dockt! Number 50-346 Licinse Number NPF-3 SerialNumber 2SS3 Attachment Page 1 of 4 REQUEST FOR EXEMPTION FROM 10 CFR 50.46,10 CFR 50.44, AND 10 CFH PART 50 APPENDIX K PARAGRAPH 1.A.5 REGARDING THE PROPOSED USE OF THE "M5" ADVANCED ALLOY FOR FUEL ROD CLADDING In accordance with 10 CFR 50.12, " Specific Exemptions," Toledo Edison (TE) requests an exemption for the Davis-Besse Nuclear Power Station (DBNPS) from the requirements specified in 10 CFR 50.46, " Acceptance Criteria for Emergency Core Cooling Systems for Light Water Nuclear Power Reactors," 10 CFR 50.44, " Standards for Combustible Gas Control in Ught-Water-Cooled Power Reactors," and 10 CFR 50 Appendix K, "ECCS Evaluation Models," Paragraph I.A.5, regarding the use of Zircaloy or ZlRLO as a fuel rod cladding material. This exemption request pertains to the proposed use of the M5 advanced zirconium alloy for DBNPS fuel rod cladding.
Backaround 10 CFR 50.46 and 10 CFR 50.44 provide various requirements for light water reactor system performance during and following a postulated loss of coolant accident (LOCA) for reactors containing oxide fuel pellets clad in either Zircaloy or ZlRLO.10 CFR 50 Appendix K Paragraph 1.A.5, requires that the Baker-Just equation be used in emergency core cooling system (ECCS) evaluation models for determining the rate of energy release, hydrogen generation, and cladding oxidation for fuel rod cladding. All three of these regulations, either implicitly or explicitly, assume that either Zircaloy or ZlRLO shall be used as the fuel rod cladding material.
In order to accommodate the high fuel rod burnups that are required for today's modern fuel management schemes and core designs, Framatome Technologies, Inc.
(FTI) developed the M5 adve.nced fuel rod cladding and fuel assembly structural material. M5 is an alloy of comprised primarily of zirconium (~99 percent) and niobium
(~1 percent) that has demonstrated superior corrosion resistance and reduced Irradiation induced growth relative to both standard and low-tin Zircaloy.
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Ducket Number 50-346 Lic:nso Number NPF-3 SerialNumber 2553 Attachment Page 2 of 4 The M5 alloy is to be used at the DBNPS for fuel rod cladding, as well as for fuel assembly spacer grids, fuel rod end plugs, and fuel assembly guide and instrument tubes. Such use of the M5 alloy at the DBNPS will permit longer fuel residence times, higher fue: burnups and reduced reload feed batch sizes, with corresponding improvements in fuel cycle economics, all while increasing performance margins with regard to fuel rod corrosion and fuel rod and fuel assembly growth. Reduced feed batch sizes will also help to reduce the spent fuel storage burden at the DBNPS.
However, the chemical composition of the MS advanced alloy differs from the specifications for either Zircaloy or ZlRLO. Therefore, absent the requested exemption, use of the M5 advanced alloy falls outside of the strict interpretation of the wording of 10 CFR 50.46,10 CFR 50.44, and 10 CFR 50 Appendix K Paragraph I.A.5.
Approval of this exemption request will allow the use of the M5 advanced alloy as a fuel rod cladding material at the DBNPS.
Basis for Exemotion Reauest 10 CFR 50.12 permits the Nuclear Regulatory Commission (NRC) to grant exemptions which are authorized by law, will not present an undue risk to the health and safety of the public, and are consistent with the common defense and security, provided that special circumstances are present. Special circumstances are present when application of the regulation in the particular circumstances is not required to achieve the underlying purpose of the rule (50.12(a)(2)(ii)). Toledo Edison believes, for the reasons described below, that the use of the M5 advanced alloy as a fuel rod cladding material achieves the underlying purposes of 10 CFR 50.46,10 CFR 50.44, and 10 CFR 50 Appendix K Paragraph I.A.5.
The underlying purpose of 10 CFR 50.46 is to ensure that facilities have adequate acceptance criteria for ECCS. FTl demonstrates in its topical report BAW-10227P,
" Evaluation of Advanced Cladding and Structural Material (MS) in PWR Reactor Fuel" (Reference 1), submitted to the NRC for review and approval on September 30,1997, that the effectiveness of the ECCS will not be affected by a change from Zircaloy fuel rod cladding to M5 fuel rod cladding. Analysis described in Reference 1 also demonstrates that the ECCS acceptance criteria applied to reactors fueled with Zircaloy clad fuel are also applicable to reactors fueled with M5 fuel rod cladding.
Dockct Number 50-346 License Number NPF-3 SerialNumber 2553 Attachment Page 3 of 4 Therefore, since the underlying purpose of 10 CFR 50.46 is achieved through the use l
of the M5 advanced alloy as a fuel rod cladding material, the special circumstances required by 10 CFR 50.12(a)(2)(ii) for the granting of an exemption to 10 CFR 50.46 do exist.
The underlying purposes of 10 CFR 50.44 and 10 CFR 50 Appendix K Paragraph l
1.A.5 are to ensure that cladding oxidation and hydrogen generation are appropriately t
limited during a LOCA and conservatively accounted for in the ECCS evaluation model. Specifically, Appendix K requires that the Baker-Just equation be used in the ECCS evaluation model to determine the rate of energy release, cladding oxidation, and hydrogen generation. FTl demonstrates, in Appendix D of Reference 1, that the Baker-Just model is conservative in all post-LOCA scenarios with respect to the use of l
the M5 advanced alloy as a fuel rod cladding material, and that the amount of hydrogen generated in an MS-clad core during a LOCA will remain within the DBNPS design basis. Therefore, since the underiying purposes of 10 CFR 50.44 and 10 CFR 50 Appendix K Paragraph 1.A.5 are achieved through the use of the MS advanced alloy as a fuel rod cladding material, the special circumstances required by 10 CFR l
50.12(a)(2)(ii) for the granting of exempticns to 10 CFR 50.44 and 10 CFR 50 Appendix K Paragraph I.A.5 do exist.
l Conclusions
- Based on the above, the underlying purposes of 10 CFR 50.46,10 CFR 50.44, and 10 l
CFR 50 Appendix K Paragraph I.A.5, which are to provide adequate acceptance L
criteria for ECCS and to ensure that cladding oxidation and hydrogen generation are appropriately limited and accounted for during LOCA evaluation, are accomplished l
through the use of the M5 advanced alloy as a fuel rod cladding material.
The granting of this exemption request would have no impact on plant radiological or non radiological effluents and involves no radiation exposure.
Because these underlying purposes have been preserved, Toledo Edison concludes 1
that the proposed exemption does not present an undue risk to the health and safety of the public and is consistent with the common defense and security.
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Docket Number 50-346 License Number NPF3 SerialNumber 2553 Attachment Page 4 of 4 Reference 1.
Framatome Technologies, Inc. (FTI) Topical Report BAW-10227P, " Evaluation of Advanced Cladding and Structural Material (MS) in PWR Reactor Fuel,"
September,1997.
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