ML19351F796
| ML19351F796 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 01/21/1981 |
| From: | Varga S Office of Nuclear Reactor Regulation |
| To: | Abel J COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8102200185 | |
| Download: ML19351F796 (2) | |
Text
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Docket Nos. 50-295 and 50-304 k
l$ c%((4h"h Mr. J. S. Abel N
Director of Nuclear Licensing j
Commonwealth Edison Company 7
Post Office Box 767 M
JAn:'o Est-g Chicago, Illinois 60690
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Dear Mr. Abel:
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On October 22, 1979, Commonwealth Edison Company (CECO s bm 1st d"an appli-cation for license amendment to increase the total nuclear peaking factor to 2.20.
On March 3,1980 we had approved a portion of the request which in-creased the then current valve of 1.86 to 1.93.
Before we can complete our review of the proposed increase above 1.03 we find it necessary that you take into consideration the issue of clad swelling and rupture. This issue came about since your October 22, 1979 request.
The NRC staff.has been generically evaluating three materials models that are used in ECCS evaluations. Those models predict cladding rupture temperature, cladding burst strain, and fuel a:;sembly flow blockage. We have (a) discussed our evaluation with vendors and other industry representatives, (b) published NUREG-0630, " Cladding Swelling and Rupture Models for LOCA Analysis," and (c) required licensees to confirm that their operating reactors would continue to be in conformance with 10 CFR 50.46 if the NUREG-0630 models were substi-tuted for the present materials models in their ECCS evaluations (See letter from D. G. Eisenhut, NRC, to All Operating Light Water Reactors, dated Novem-ber 9,1973).
Until we hace completed our generic review and implemented new acceptance criteria for cladding models, we have required that the ECCS analyses be accompanied by supplemental calculations to be perfomed with the materials models of NUREG-0630.
For these supplemental calculations only, we have accepted other compensatory model changes allowed for the confirmatory oper-ating reactor calculations mentioned above. However, for Zion the compensa-j Lory changes are exactly those requested on your October 22, 1979 letter and, of course, cannot be doubly accaunted for.
A new concern was discovered by Westinghouse who fomally notified the staff in hovember 1979. Specifically, Westinghouse had discovered that the February 1978 ECCS evaluation model was, in part, based on cladding burst tests which were conducted at relatively fast temperature-ramp rates; whereas the LOCA ana-lyses of actual plant heatup rates (including those of Zion) were at relatively slow temperature-ramp rates. We therefore require that the licensee assess the impact of this calculational error and the NUREG 0630 models via an interim supplemental analysis. This interim sup%emental analysis would be similar to that provided by CECO on January 8,1980.
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However, the analysis should be based on the results provided in the Octo-ber 22,1979 submittal which explicitly accounts for the credits based on "UHI technology" and removal of the 65* F pellet temperature uncertainty.
Therefore the estimated credit discussed in paragraphs B and D of enclo-sure 2 to the January 8,1980 letter would of course not be used. With this interim supplemental analysis and any necessary changes to the pro-posed technical specifications, we should be'able to complete our review.
If you have any questions, please let us know,
, Sincerely,
.\\
t ar ef Operating Reactog Brar.ch #1 Division of Licens ng cc:
See next page b
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4 Mr. J. S. Abel Commonwealth Edison Company cc: Robert J. Vollen, Esquire 109 North Dearborn Street Chicago, Illinois 60602 Dr. Cecil Lue-Hing Director of Research and Development Metropolitan Sanitary District of Greater Chicago 100 East Erie. Street Chicago, Illinois. 60611-Zion-Benton Public: Library District 2600 Emmaus Avenue Zion, Illinois 60099 Mr. Phillip P. Steptoe 4
Isham, Lincoln and Beale Counselors at' Law One First Natichal Pla:a 42nd Floor Chicago, Illinois 60603 Susan N. Sekuler, Esquire Assistant Attorney General Environmental Control Division 188 West Randolph Street, Suite 2315
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Chicago, Illinois 60601 U. S. Nuclear Regulatory Commission Resident Inspectors Office 105 Shiloh Blvd.
Zion, Illinois 60099
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