ML20197D393

Discusses Preparations for Subj Facil Extended Burnup Prog Incl Fuel Sipping Test & Fuel Assemblies Exam Prog.Reaffirms Request to NRC to Expedite Lic Mod Review & Approve Changes to Higher Region Average Fuel Burnup Tech Specs by 781220

ML20197D393
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	11/21/1978
From:	Reed C COMMONWEALTH EDISON CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
NUDOCS 7811280278
Download: ML20197D393 (3)

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C:mm:nwsalth Edis n

.. - 7 One First National Plaza. Chicago, llhnois O Address Reply to: Post Office Box 7(i7 Chicago Illinois 60690 November 21, 1978 l

Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Zion Station Units 1 and 2 Information on Extended Burnup Program NRC Docket Nos. 50-295 and 50-304 P Reference (a) : October 27, 1978 letter from Cordell Reed to Director of Nuclear Reactor Regulation

Dear Mr. Denton:

Per Reference (a) , Commonweagth Edison Company requested a license modification to extend the F gg rod bow penalty curve and the EFPH clad collapse limits in the Zion Station Technical Specifications to include higher region average fuel burnups. This modification was requested in anticipation of the inauguration of an extended burnup progren at Zion Station. In Reference (a),

Commonwealth Edison also indicated that additional information on the scope of the extended burnup program planned for Zion Station, including proposed fuel examinations, technical and safety reviews, would be provided at a later date. For your information, a description of the scope of the Zion Extended Burnup Program follows.

Commonwealth Edison is currently reviewing an EPRI/

Westinghouse proposal to operate the upcoming Cycle 4 of Zion Unit 2 with four Region 3 fuel assemblies recently discharged (Fall 1978) from Zion Unit 1. The reinsertion of these four assemblies for an additiona1 cycle of operation would increase their burnup exposures to about 47,000 MWD /MTU. This EPRI/

Westinghouse program is part of a Department of Energy initiated effort to improve uranium fuel utilization without reprocessing by extending the burnup of nuclear fuel elements. The Zion program is intended to demonstrate that the Westinghouse fuel ascebmlies used in the Zion plants are capable of operating satisfactorily to the higher burnups deened necessary for improved fuel utilization. If, after completing this additional cycle of operation, these assemblies have demonstrated satisfactory fuel performance, they might be re-inserted for a fifth cycle to increase their exposure to about 55,000 MWD /MTU. 0\

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"' - Commonwsalth Edisen NRC Docket Nos. 50-295/304 Mr. Harold R. Denton: November 21, 1978

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Commonwealth Edison has been reviewing the EPRI/

Westinghouse proposal to assure, as a minimum, the program for Zion Unit 2 Cycle 4 will not:

3 (1) Adversely affect safe operation of the Zion l plants; (2) Increase coolant activity levels; or (3) Require a reduction in plant capacity, availability, or flexibility.

This detailed review has included examining the effects  :

3 of extended burnups on fission gas release, clad strain including I strain concentrations, clad stress, halogen stress corrosion cracking, leaking fuel element performance, rod bow penalties on N

, F dH, accelerated " waterside corrosion", massive local internal hydriding, uranium oxidation in leaking fuel and clad flattening.

Although Westinghouse has virtually no experience with

full size fuel assemblies irradiated to these burnups, irradiation j tests of single fuel rods have been performed by Westinghouse to l

! exposures of 58,000 MWD /MTU. This experience provides a basis for 3 assuring satisfactory operation of these assemblies to the intended ,

extended burnups. j i

I Commonwealth Edison and Westinghouse are proceeding with

) preparations for the Zion Extended Burnup Program including an anticipated fuel sipping test and an examination program of the four fuel assemblies prior to their reinsertion for their fourth fuel c a ele. The sipping test is intended to assure that no leaking fuel elements are used in the extended burnup program. The fuel examinations tentatively include nondestructive rod exams of single rods taken from one of the assemblies, measurements of rod bow, and visual / television exams of the fuel assemblies. These exams are intended to provide additional detailed information on fuel element behavior as well as assurance that no unfavorable rod behavior has occurred prior to the start of the program. In addition, plans are being formulated for extensive fuel element exams upon completion of the extended irradiations.

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Commonwealth Edison NRC Docket Nos. 50-295/304 Mr. Harold R. Denton: November 21, 1978 As with past Zion reloads, the upcoming Zion Unit 2 Cycle 4 reload core desigit including the extended burnup assemblies t/ill undergo Commonwealth Edison on-sice and off-site review to insure that there are no unreviewed safety questions associated with the reload.

However, prior to commencing the Zion Extended Burnup Program, the proposed license modification described in Reference (a) murt be approved. Therefore, in order to facilitate a decision to inaugurate this program, Commonwealth Edison reaffirms its request to the NRC Staff to expedite its review and approval by December 20, 1978 of the proposed amendment change described in Reference (a).

Very truly yours, Cordell Reed Assistant Vice-President l

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