ML17261B044
| ML17261B044 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 04/12/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17261B043 | List: |
| References | |
| NUDOCS 9004200433 | |
| Download: ML17261B044 (3) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDYiENT NO. 39 TO FACILITY OPERATING LICENSE NO. DPR-18 ROCHESTER,GAS AND ELECTRIC CORPORATION R. E.
GINNA NUCLEAR POWER PLANT DOCKET NO. 50-244
1.0 INTRODUCTION
By letter dated February 16, 1990, as supplemented on March 15, 1990, Rochester Gas and Electric Corporation submitted an application for amendment to the Technical Specifications for the R.E. Ginna Nuclear Power Plant.
The changes involve an expansion of the use of dummy rods (Zircaloy-4 or stainless steel rods) in fuel assemblies from the core peripheral location to other locations.
However, in order to justify this expansion of utilizing dummy rods in other locations, cycle-specific reload analysis is required.
The licensee has provided such an analysis.
The Office of Nuclear Reactor Regulation's evaluation is as follows:
2.0 EVALUATION The dummy rods (Zircaloy-4 or stainless steel rods) were originally used in fuel assemblies to replace those fuel rods damaged by the baffle jetting problem in the Westinghouse reactors.
The concept was extended further to replace failed rods during reconstitution of fuel assemblies in other locations.
However, in order to satisfy generic fuel design criteria'as described in the NRC Standard Review Plan (NUREG-0800), the dummy rods require thermal-hydraulic analyses to demonstrate that inclusion of the dummy rods in fuel assemblies with the specific configurations and core locations chosen for a specific fuel cycle is acceptable with respect to the overall fuel performance and safety-significant conclusions.
The licensee has analyzed the dummy rods by assuming that dummy rods operate at power levels equal to the highest power in any nf the fueled rods in the reconstituted assembly.
The licensee stated'that this results in a conservative analysis with less margin than actually exists to the DNBR acceptance limit in the reconstituted assembly.
The staff agrees that this analysis procedure should be sufficiently conservative to offset uncertainties associated with application of the approved DNBR correlation to reconstituted fuel assemblies which have fuel rod configurations slightly different than those represented in the DNBR test data base.
- However, core wide analyses will result in a 90042004~,
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"2-non-conservative calculation with erroneous redistribution of flow from the reconstituted fuel assemblies to other assemblies in the core'.
This effect should be small and is probably negligible for the limited core alterations planned for Ginna Cycle 20 based on telephone discussions between the staff and the licensee.
However, the licensee should perform confirmatory analyses using realistic power distributions for the reconstituted assemblies to assure that DNBR limits are not violated for the conventional fuel assemblies during Cycle 20 operation.
This additional evaluation should also be included in the safety analyses for all future cycles employing fuel assembl'ies reconstituted with dummy pins at high power core locations.
The licensee has also addressed the impact of up to 10 dummy fuel rods in a
'egular fuel assembly on the capability of a reconstituted assembly to withstand seismic and-LOCA loading conditions.
The filler rod(s) have outside diameters identical to the fuel rod diameter and the rod length is also the same.
The grid strength will remain unchanged since the filler rod(s) will provide the same support in the grid cells as the fuel rods.
For a small number of filler rod(s)
(10 or less),
the change in mass and stiffness of the fuel assembly will be insignificant.
There will be negligible effects on fuel assembly dynamic properties, such as fuel fundamental frequency.
- Thus, the load carrying capability of the fuel assembly and grid spacers is not affected under the seismic and LOCA design loading conditions for the recon-stituted fuel.
The staff concludes that this assessment is reasonable and acceptable.
The licensee stated that each reload that contains reconstituted assemblies will be evaluated using approved methods described in WCAP-9273A, "Westinghouse Reload Safety Evaluation Methodology," dated July 1985.
The effect of the actual reconstitution on core performance parameters, peaking factors, core average linear heat rate, and LOCA-related analyses will be evaluated to ensure that the existing safety criteria and design limits and the original fuel assembly design criteria are satisfied.
The staff finds that this approach is acceptable since the analysis methods have previously been approved except for the DNBR evaluation for the reconstituted assemblies.
A method for the latter evaluation, assuming that filler rods are operating at the highest Power in the reconstituted
- assembly, is approved for Ginna by incorporationin the Technical Specification Basis.
Technical Specifications changes are as follows:
(1)
Section 5.3.1 Reactor Core In Section 5.3.1, the fuel assembly at any time may consist of fuel rods clad with Zircaloy-4 or dummy rods with Zircaloy-4 or stainless steel if justified by cycle-specific analysis.
The proposed Technical Specification further restricts the use of dummmy rods; if there are more than 30 rods in the core or 10 rods in any assembly, a report describing the number of dummy rods and associated cycle-specific evaluation shall be submitted to NRC prior to criticality.
We agree with the licensee approach.
(2) 5.3. 1 Basis In Section 5.3. 1 Basis, the licensee states that the, DNBR for the reconstituted assembl.ies is conservatively determined by assuming that the filler rods are-operating at the highest power in the reconstituted fuel assembly as previously described.
We approve the licensee analysis.
.The Office of Nuclear Reactor Regulation concludes this evaluation as follows:
We have reviewed the licensee submittal of Technical Specification changes for R.
E. Ginna and the proposed approach to safety analyses to assure that fuel assembly design changes will not result in failure to meet the pertinent design safety criteria.
We conclude that the proposed Technical Specification revisions are acceptable and that the required cycle-specific evaluation
- approach, including DNBR evaluation of the reconstituted fuel assembly as described in the proposed Technical Specification Basis, is acceptable when the use of dummy rods is restricted to no more than 10 rods in any fuel assembly or 30 rods in the core.
The licensee is cautioned that the application of these methods to cores with more extensive use of dummy fuel rods will'require further justification, which should be provided to the NRC for review well in advance of the intended appli-cation.
In addition, the DNB evaluation methods described herein are not approved for generic applications.
ENVIRONMENTAL CONSIDERATION Notice of Consideration by the staff of issuance of the proposed amendment was published in the Federal Register on March 2, 1990 (55 FR 7611) and no comments or request for hearing was received.
The Commission also consulted with the State of New York and no comments were received.
An Environmental Assessment (EA) and Finding 'of No Significant Impact was published in the Federal
~Re ister on April 12, 1990 (55 FR 13864).
Based upon the EA, the staff has determined not to prepare an environmental impact statement for the proposed license amendment, and has concluded that the proposed action will not leave a
significant adverse effect on the quality of the human environment.
CONCLUSION The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed
- manner, and (2) such activities will be conducted in compliance with the Commission s regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
R.
C.
Jones Dated:
April 12, 1990