ML20205K816
| ML20205K816 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 03/03/1986 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML17342A605 | List: |
| References | |
| NUDOCS 8603130424 | |
| Download: ML20205K816 (3) | |
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I SAFETY EVALUATION OF WCAP-10444-P ADDENDUM 1 EI 1.
INTRODUCTION By letter dated December 23,1985 from E. P. Rahe, Jr. (Westinghoveet-to H. Berkow (NRC), Westinghouse submitted a topical report entitled, " Reference i
Core Report Vantage 5 Fuel Assembly". WCAP-10444, Addendum 1 for NRC review and approval. This document extends the applicability of the Integral Fuel Burnable Absorber (IFBA) design features of 17x17 VANTAGE 5 fuel assemblies to other Westinghouse fuel, assembly designs, i.e., Westinghouse 14x14 and i
15x15 fuel arrays. The VANTAGE 5 fuel design including 1FBA features received an NRC approval in July 1985 (letter from C. D. Thomas to E. P. Rahe, Jr. dated July 1985).
i The IFBA design is a thin boride coating on the fuel pellet surface. The stack length of coated pellets varies depending on the specific fuel rod design. IFBAs provide power peaking and moderator temperature coefficient control. Additional helium release to the void volume of the fuel red due to l
the borjde coating interaction with neutrons must be accounted for in the analysis.
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EVALUATION Westinghouse has analyzed the impact of IFBA on fuel mechanical, nuclear, and thermal and hydraulic designs for various fuel rod designs according to the SRP criteria of fuel system damage mechanisms, fuel rod failure mechanisms, and fuel coolability. The findings are similar to the conclusions in the approved VANTAGE 5 fuel design (WCAP-10444-P-A). Our evaluation (provided below) focuses on the more significant characteristics of 14x14 and 15x15 fuel designs.
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2.1 Fuel Rod Internal Pressure Because of boride coating on the pellet surface, additional helium will be 1
1 generated and released to the plenum space. Westinghouse modified the
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fission gas release model in the approved PAD 3.3 code to include this effect. The result showed that the rod internal pressure met the design criteria described in the approved report WCAP-8964. We thus conctuWe that the rod pressure analyses for the 14x14 and 15x15 IFBA designs are acceptable.
I 2.2 Cladding Stress and Strain Due to a larger pellet outer diameter, the pellet-clad gap is smaller. It is
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expected that IF8A fuel rods have higher stress and strain than uncoated fuel rods. However. Westinghouse used the approved PAD 3.3 code to verify that the clad stress and strain of IFBA fuel fods meet the criteria in the s'pproved report WCAP-10444-P-A. We, therefore, conclude that the cladding stress and strain analyses for 14x14 and 15x15 IFBA designs are acceptable.
i 2.3 Fuel Centerline Temperature l
The IF8A fuel centerline temperature during operation may be different from non-IF8A fuel due to a smaller pellet-clad gap affecting gap conductance.
Westinghouse used the approved PAD 3.3 code and confirmed that the maximum fuel temperatures for IF8A fuel were bounded by those generated for non-IFBA fuel. We, therefore, conclude that this fuel temperature analysis is acceptable.
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4 2.4 Nuclear Design i
i The nuclear design methods and models (WCAP-9272-P-A) have been approved for use in IF8A fuel as indicated in WCAP-10444-P-A. These methods and models were consistently used for 14x14 and 15x15 IFBA fuel. We thus consider the nuclear design of 14x14 and 15x15 IFBA fuel rods to be acceptable.
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e 2.5 Thermal-Hydrculic Design The effect of IF8A fuel on thermal-hydraulic design consideration is to flatten the axial power distribution and reduce power peaking. Westinghouse has examined this effect and found that the design axial power distribution used in the determination of the over-temperature AT setpoint conservatively covered any IFBA fuel related effects on core power distribution. The same conclusion has been approved in our SER on WCAP-10444-P-A. No changes in thermal-hydraulic design methods and models were introduced for 14x14 and 15x15 IF8A fuel. We thus conclude that the thermal-hydraulic design of 14x14 and 15x15 IF8A fuel is acceptable.
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CONCLUSION Based on the approved 17x17 VANTAGE 5 fuel design (WCAP-10444-P-A) and the acceptable fuel mechanical, nuclear, and thermal-Wraulic design considerations, we conclude that the IF8A feature can be applied to Westinghouse 14x14 and 15x15 fuel designs for Itcensing applications.
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