ML17310A584
| ML17310A584 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 09/02/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17310A582 | List: |
| References | |
| NUDOCS 9309140098 | |
| Download: ML17310A584 (4) | |
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UNITEDSTATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 CLOSURE 1
SAFE Y EVALUATION BY THE OFFICE OF NUCLEAR REACTOR R
GU A ON RELATING TO FUEL SSEMBLY SHOULDER GAP M ASU MENTS RIZONA PUBLIC SERVICE COMP N
PAI.O VERDE NUCLEAR GENERATING STATION UNITS 1
2 AND 3 DOCKET NOS. 50-528 50-529 ND 50-530
1.0 INTRODUCTION
By letter dated January 25, 1993, Arizona Public Service Company submitted the results of fuel rod shoulder gap measurements made by ABB-Combustion Engineering (ABB-CE) during the End-of-Cycle 3 outage at Unit l.
The shoulder gap is the span between the top of the fuel rod and the upper tie plate.
The shoulder gap clearance is needed due to differential growth among fuel rods and guide tubes.
A total of 10 fuel assemblies were inspected.
The inspection involved the use of a periscope to optically measure the shoulder gap of peripheral fuel rods and a guide-tube tool to measure the length of the outer guide tubes.
The licensee has continued to measure the shoulder gap clearance for three cycles based on its commitment documented in the NRC Safety Evaluation Report, Supplement 8.
Based on these shoulder gap measurements, the licensee stated that the commitment is no longer necessary and that future measurements are unnecessary.
- 2. 0 EVALUATION The licensee measured the fuel rod growth for three cycles for a total neutron fluence of 10 '/cm.
The growth rate results indicated that the Palo Verde fuel rod growth was below the ABB-CE design curve.
The licensee also measured the guide tube growth for three cycles.
The results of the guide tube growth showed that its growth continues to be greater than the lower 95X predicted growth.
Based on the conservative assumption of minimum guide tube growth and maximum fuel rod growth that results in the most shoulder gap reduction, the licensee showed that the shoulder gap decrease was within the design basis.
- Thus, adequate margin for shoulder gap reduction has been maintained for assembly average burnup of 44,000 MMd/MTU.
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The staff has reviewed the licensee's data and analysis.
Due to the identical nature of the fuel in all the Palo Verde units, shoulder gap measurements performed on Unit I will be adequate to predict fuel behavior in Units 2 and 3.
Based on the above and the conservative assumptions for calculating shoulder gap, the staff concludes that shoulder gap clearance is adequately maintained for Palo Verde Units 1, 2, and 3.
- 3. 0 CONCLUSION We have reviewed the licensee's submittal of shoulder gap measurements for Palo Verde Unit l.
Based on the staff's evaluation of the shoulder gap clearance, we conclude that the licensee has provided reasonable assurance that adequate shoulder gap clearance is being maintained and the commitment to perform shoulder gap measurements is no longer necessary for Palo Verde Units I, 2, and3.
Principal Contributor:
S.
L.
Wu Date:
September 2,
1993
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