ML17215A767
| ML17215A767 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 02/19/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17215A766 | List: |
| References | |
| NUDOCS 8503050559 | |
| Download: ML17215A767 (1) | |
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UNITEDSTATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY. EVALUATION.BY THE OFFICE OF NUCLEAR REACTOR REGULATION FLORIDA POWER AND LIGHT COMPANY ST.
LUCIE PLANT UNIT NQ.
1 DOCKET-%0. 50-335 4
1
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In Amendment No. 63 to Operating License DPR-67, the staff imposed a license condition stating that the licensee must use an approved method to show that the Combustion Engineering (CE) fuel remaining in the core will not experience collapse prior to reaching 38,000 Mltd/MTU peak assembly burnup.
The staff has previously reviewed and "approved the new Exxon Nuclear Corporation (ENC) creep. collapse method (letter from J.D. Neighbors to C.
W. Giesler, June 19,
'984 This method has been used by the licensee to demonstrate that the Exxon fuel in St. Lucie Unit 1 will not collapse during its residence in the core provided certain criteria are met.
The licensee also stated that the CE fuel in the core will not collapse-based on calculations using the Exxon methodology.
4 However, the staff questioned the applicability of the ENC method to CE fuel in the core of St. Lucie 1 since the data base for the Exxon method is based pri-marily on Exxon fuel (letter from J.
R. Miller to J.
W. Williams, Jr., July 5, 1984).
By letters dated September 17, 1984 and February 4, 1985 from J.
W.
Williams, Jr. to J.
R. Miller, the licensee responded to the staff concern.
First, the liqensee indicated that bounding values of two important parameters, creepdown rate and densification, for St. Lucie 1 fuel were used in the ENC method.
- Second, ENC has visually examined over 1,000 fuel rods in St. Lucie 1
in the burnup range of from 10,000 to beyond 20,000 MWd/MTU for discoloration, which would Confirm axial gap formation.
No significant discoloration was
- observed, which implied no axial gaps.
The absence of axial gaps is a necessary condition for the Exxon creep collapse model to be valid.
Thus, the licensee has demonstrated that the Exxon model is valid and that it was applied to the CE fuel conservatively.
Some confirmatory evidence of the validity of the conclusion that no collapse is expected in the St. Lucie'1 CE designed fuel'comes from the fact that no collapse has been reported in the Combustion Engineering high burnup program.
Therefore, use of the ENC methodology on CE fuel is acceptable..
Date:
February 19, 1985 Principal Contributors:
S.L.
Wu D.
E. Sells 8503050559 8502i9 PDR ADOCK 05000335,'
PDR I'