ML20236U182

Safety Evaluation Supporting Util 870724 Evaluation Demonstrating That Adequate Shoulder Gap Will Be Provided in Cycle 3 & Subsequent Cycles

ML20236U182
Person / Time
Site:	Waterford
Issue date:	11/24/1987
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20236U178	List: ML20236U176 ML20236U182
References
NUDOCS 8712020338
Download: ML20236U182 (2)

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO SHOULDER GAP LICENSE CONDITION LOUISIANA POWER & LIGHT COMPANY WATERFORD STEAM ELECTRIC STATION, UNIT 3 DOCKET NO. 50-382 i

1. 0 INTRODUCTION License condition 2.C.7 of Facility Operating License No. NPF-38 for the Waterford Steam Electric Station, Unit 3, operated by Louisiana Power and Light Company (LP&L, the licensee) requires that adequate shoulder gap be provided in the fuel element. assemblies for each cycle of operation. By letter dated July 24, 1987, LP&L submitted a shoulder gap evaluation 1 demonstrating that adequate shoulder gap will be provided in Cycle 3 and subsequent cycles. l l

2. 0 DISCUSSION

' Insufficient shoulder gap clearance in Combustion Engineering (CE) 16x16 fuel was discovered at ANO-2. Similar symptoms were also discovered for CE 4

14x14 fuel at Calvert' Cliffs. The NRC staff investigated this shoulder gap l

problem for all CE plants. A shoulder gap closure will result in assembly i bowing and decreasing DNBR margin. A license condition was thus imposed for  ;

Waterford Unit 3 to prevent shoulder _ gap closure. License condition 2.C.7  !

of the Waterford 3 operating license states that:

" Prior to entering Startup (Mode 2) after each refueling, the i licensee shall either provide a report that demonstrates that i the existing fuel element assemblies (FEA)'have. sufficient available shoulder gap clearance for at least the next cycle of operation, or identify to the NRC and implement a modified  !

FEA design that has adequate-shoulder gap clearance for at least the next cycle of operation. This requirement will apply until

.the NRC concurs that the shoulder gap clearance provided is i adequate for the design. life of the fuel."

l The licensee submitted a report entitled, " Cycle 2 Shoulder Gap Evaluation l

CEN-335(C)-P" to support the Cycle 2 reload. This report was subsequently approved by the Staff. . Based on Cycle 2 measurements and the approved data base technique in CEN-335(C)-P, the licensee provided a Cycle 3 shoulder-gap evaluation in a letter from K. W. Cook to NRC dated July 24, 1987, in accordance with the license condition requirement.

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3.0 EVALUATION Three different batches of fuel assemblies will be irradiated during Cycle 3.

The licensee has calculated the fluence limits in Cycle 3 for all three-batches using the method described in CEN-335(C)-P. For each of the three batches, the estimated fluences are within the fluence limits. Hence,_the shoulder gaps, which are a function of fluence, are adequate for Cycle 3.

The staff has reviewed the results and concludes that adequate shoulder gap has been provided for Cycle 3.

Based on the acceptable shoulder gap analysis results for the_first-3 cycles, the. licensee concluded that there is sufficient information and conservatism to maintain an adequate shoulder gap clearance for. fuel rod design lifetime.

Any future design change will necessitate a reevaluation of the fluence limit to ensure conservative shoulder gap clearance prediction. The staff agrees with the licensee's. assessment. Since no shoulder gap problems have been observed at Waterford and the licensee will continue to verify that the fuel rod fluences do not exceed the acceptable fluence limit, the-staff concludes that the licensee has demonstrated an acceptable method for evaluating shoulder.

gap clearance during fuel rod lifetime. Thus, license condition 2.C.7 may'also be closed for Cycle 4 and subsequent cycles.

4.0 CONCLUSION

l The staff has reviewed the licensee's shoulder gap submittal for Cycle 3 l

! and subsequent cycles and concludes that-the licensee has demonstrated

! that fuel element'asseblies will has sufficient available shoulder gap l clearance. Thus, the license condition 2.C.7 of the operating license for Waterford 3 is considered closed for Cycle 3 and subsequent cycles.-

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Principal contributor: 5. Wu Dated: November 24, 1987