ML20079M285
| ML20079M285 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 10/29/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20079M284 | List: |
| References | |
| NUDOCS 9111080128 | |
| Download: ML20079M285 (3) | |
Text
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s gv.... f SAFETYEVALUATIONBY1HEOFQCEOFNUCLEARREACTORREGULAT10h REL ATED TO AMEN 0 MENT NO.166 TO FACILITY OPERATING LICENSE NO. NPF-3 ELE 00EDISONCOMPANY CENTER 10R SERVICE COMPANY
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THE CLEVELAND _ ELECTRIC ILLUMINATING COMPANY DAVIS BESSE _ NUCLEAR POWEp ST ATION, L' NIT NO.1 DOCKET NO. 50-346
- 1. O INTRODUCT10N Toledo Edison Company (ion 5.3.1, Fuel Assemblies, TE) sub:nitted an By letter dated May 31, 1991, application for an amendment to Technical Specificat for Davis-Desse Nuclear Power Station (DBNPS).
The proposed e,hange would alles the use of stainless steel filler rods to replace defective fuel rods, Subsequent to meetings with NRC staf f on August 14 and 21, '.991, TE prov ided supplemental information by letter dated August 29, 1991.
In respnose to the NRC staff request, additional information was provided by letter dated October 15, 1991 describing the fuel inspection and repair process, the cycle specific vendor redesign analyses, the plan for use of a single stainless steel filler redinasinglerepairedfuelassemblyintheCycic8 core,theproposed core location of tne repaired assembly, and the minimum thermal niargin available compared to the limiting assembly. That information did not alter the proposed action or affect the determination published September 25, 1991.
Our evaluation follows.
2.0 EVALUATION The replacement of damaged fuel rods with non-fuel stainless steel filler rods has been previously implemented at other Babcock and Wilcox (B&W) designed facilities. The proposed technical specification is considered acceptable since it requires that the number and location of filler rod substitutions are limited to configurations for which applicable NRC approved codes and nethods are valid and that have been shown by test or analyses to comply with all fuel safety design bases.
The licensee stated in the meeting of August 21, 1991, that thermal hydraulic ar.alysis of the proposed insertion of a cold rod into the center of a 3x3 matrix of active fuel is supported by test data which includes 3x3, 4x4 and Sx5 rod configurations.
The fuel vendor intends to submit a licensing topical report documenting the OKB tests described in that meeting in support of the position that the use of the Babcock & Wilcox CWC CHF correlation is applicable to the proposed configuration. Although the c'1110001DO 911029 l
- DR ADOCK 05000346 P
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2 cycle-specific vendor analyses to support the Cycle 8 redesign are still in progress, the repaired assembly will be located in a non-limiting core j
location with greater than 5 percent margin relative to the lead power i
generation fuel assemblies.
This nargin is considered sufficient to assure I
that the repaired assembly will not be limiting with respect to DNB occurring during Cycle 8.
Structural evaluations completed by the vendor also indicate that replacement of fuel rods with stainless steel rods does not adversely affect the performance of a fuel assembly during combined loss-of-coolant accident (LOCA) and seismic loads.
The filler rod material (SS304) is a standard reactor grade material.
The radial thermal expansion of the stainless steel rod is greater than a Zirctioy-4 c!dd fuel rod, resulting in more compression of the spacer grid springs.
However this is still within the elastic range and no adverse effect is translatable to adjacent fuel rod grid springs.
The axial expansion differential is handled by leaving a gap of 1.7 inches (cold) between the top of the fillcr rod and the bottom of the upper end fitting.
Analyses show sufficient clearance with no interference or rod bow potential. The filler rod design also has no effect on the hydraulic lift characteristics of the fuel assembly.
The staff concludes that this mechanical assessment is reasonable and acceptable.
The staff has review the itcensee's submittals for replacement of defective fuel rods with stainicss steel rods.
Based on the information supplied by the licensee and the staff's review of the evaluation method and acceptance criteria for the analyses being perf ormed prior to the startup of the Cycle 8 core, the staff concludes that the proposed Technical Specification change is acceptable, and that the methodology used is acceptable for the proposed Cycle 8 core. Approval of the BWC CHF correlation for application to other reconstituted fuel assenbly and reactor core configurations will require further review.
3.0 STATE CONSULTATION
in accordance with the Commission's regulations, the Ohio State official was notified of the proposed issuance of the amendn.ent. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
This amendment changes a requirement with respect to installation or use of a facility com>onent located within the restricted area as defined in 10 CFR Part 20 or c$anges a surveillance requirement.
The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Consnission has previously issued a proposed finding
i 3-that the amendment involves no significant hazards consideration and there has been no public consent on such finding (56 FR 29282 and 56 FR 48591). Accurdingly, the anendment meets the eligibility criteria for categorical exclusion set forth in10CFR51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment,
5.0 CONCLUSION
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The staff has concluded, based on the considerations discussed above, that:
j not be endangered by operation in the proposed manner, (2) y of the public w (1) there is reasonable assurance that the health and safetsuch activities will be conducted in compliance with the Commission's regulations, and (3) the j
issuance of this amendment will not be inimical to the conson defense and security or to the health and safety of the public.
Principal Contributor:
E. Kendrick Date:
October 29, 1991 I
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