ML20205M340

License Change Application 139 for Amend to License NPF-1, Deleting Fuel Rod Weight Limit in Tech Spec Section 5.3.1

ML20205M340
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	04/11/1986
From:	Withers B PORTLAND GENERAL ELECTRIC CO.
To:
Shared Package
ML20205M338	List: ML20205M335 ML20205M340 ML20205M349
References
TAC-61235, NUDOCS 8604150190
Download: ML20205M340 (5)

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PORTLAND GENERAL ELECTRIC COMPANY EUGENE WATER & ELECTRIC BOARD AND PACIFIC POWER & LIGHT COMPANY Operating License NPF-1 Docket 50-344 License Change Application 139 This License Change Application requests a modification to Appendix A of Operating License NPF-1 for the Trojan Nuclear Plant to delete the fuel rod weight limit in Section 5.3.1 of the Trojan Technical Specifications.

PORTLAND GENERAL ELECTRIC COMPANY l By ,

_- 2 2 Bart D. Withers Vice President Nuclear Subscribed and sworn to before me this lith day of April 1986.

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Notary Public of Orgfon My Commission Expires: < #

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LCA 139 Page 1 of 5 REASON FOR CHANGE Design Features Section 5.3.1, Fuel Assemblies, of the Technical Specif1-cations, identifies a maximum total fuel rod weight of 1,760 grams of uranium. Recent changes to the fusi design, including Chamfered pellets with a reduced dish and use of the integrated dry route process, have increased fuel weights slightly. The weight increases have caused the assembly averaged fuel rod woight to exceed the maximum value by as much as 13 grams over the 1,760 gram limit. This change will delete f.he weight limits to allow use of the current fuel in compliance with the Technical Specifications.

DESCRIPTION OF CHANGE The reference to a maximum fuel content of 1,760 grams of uranium As deleted from Design Features Section 5.3.1 (see Page 5 of this attachment for the changes).

SAFETY / ENVIRONMENTAL EVALUATION Summary of Change The proposed change to Pesign Features Section 5.3.1 of the Trojan Technical Specification deletes the maximum fuel rod weight limit of 1,760 grams of uranium. The purpose of the change is to permit the use of assemblies found to be over the weight limit. The amount that the average rod in the assembly of greatest weight exceeds the limit is less than 1 percent. It is judged that this weight difference is not signifi-cant, that other Technical Specifications cover the important fuel parameters, and that deleting the Design Features fuel rod weight limit is not safety significant.

Evaluation The proposed change of Technical Specification Design Features section 5.3.1 is shown on Page 5 of this attachment. This is the only reference to fuel rod uranium weight in the Technical Specifications.

The Trojan Updated FSAR identifies core weight of UO2 (in pounds) and the linear rod weight of UO2 (in pounds per foot) for the initial (Cycle I) core. The Trojan Updated FSAR values appear to be for informa- J tional purposes only. The NRC Standard Technical Specifications for I Westinghouse list a maximum fuel rod uranium weight of 1,766 grams; the Trojan value is 1,760 grams. There is no indication as to why the fuel weight is listed in the Technical Specifications or what the significance is.

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Although a number of areas involving safety analysis are affected by fuel weight, the areas of safety significance.have their own limits. Techni-cal Specification limits on power and power distribution control the fission rate, and hence, the rate of decay heat production. Fuel rod I

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LCA 139  !

! Page 2 of 5 weight does not have any bearing on the power limits, power operating l' level, or decay heat rate. The composition of the fuel is very closely monitored to assure acceptable fuel performance for such things as ,

thermal conductivity, swelling, densification, etc. The fuel weight

changes that could be made without a Technical Specification limit are

{ not of sufficient magnitude to cause a significant difference in fuel f performance as warranted by the fuel vendor. There are no expected observable changes in normal operation due to the expected fuel rod f weight changes, and the important fuel parameters have already been

considered by the fuel vendor; this will be addressed in the Cycle 9

! Reload Safet/ Evaluation.

! Other Design Basis Events were examined to assess the effects of possible j changes in fuel rod weight. Fuel rod weight will only change as a result '

of a specific change in the nuclear design, which will be addressed in

] the Cycle 9 Reload Safety Evaluation, or as a result of the acceptable

$ manufacturing tolerances, in which case the changes in fuel rod weight 3

are slight. Changes in nuclear design resulting in fuel rod weight changes will be controlled by their own limits as discussed above.

Changes in fuel rod weight due to manufacturing tolerances would be within 1-2 percent. For these changes, the effect on new and spent fuel criticality analyses remain bounded by the existing analyses and Techni-cal Specification Design Features limits. Fuel-handling equipment and '

procedures are not affected by weight changes within manufacturing tolerances. Seismic performance contains sufficient conservatism to bound manufacturing tolerances. Other accident analyses are not affected by rod weight as a direct parameter, and the existing analyses will i remain bounding.

No unreviewed environmental questions, reductions in quality assurance l commitments, decreases in the effectiveness of the RERP, or decreases in i the effectiveness of the Security Plan result from this change.

I j conclusion In summary, the deletion of the fuel rod weight limit in the Technical Specifications is proposed because the limit is not related to the safety of the Plant. Other Technical Specification limits provide the bounding safety parameters for Plant operation. Deletion of uranium weight limits in Technical Specification Design Features 5.3.1 will have no effect on the Plant safety, and will permit use of existing fuel assemblies.

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LCA 139 i Page 3 of 5 SIGNIFICANT HAZARDS DETERMINATION L

In accordance with the requirements of 10 CFR 50.92, the enclosed application is judged to involve no significant hazards based on the following information:

1. Does the proposed license amendment involve a significant increase in the probability or consequences of an accident previously evaluated?

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Response

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The deletion of fuel rod uranium weight limits does not increase the

probability or consequences of previously evaluated accidents. The change in fuel rod weight that could occur without a Technical i a Specification limit is small because other fuel design constraints such as rod diameter, gap size, UO2 density, fuel active lengths, l etc limit the variation in rod weight. The current safety analyses are not based on fuel rod weights, but more on parameters such as power, thermal conductivity, fuel dimensions, etc. These parameters are either (1) not affected at all by fuel rod weight, or (2) are only slightly affected. However, a review of parameters which may be

{ affected indicates that a change in fuel weight does not cause other

] parameters to exceed the values assumed in the safety analyses, or to i cause acceptance criteria to be exceeded. The slight effects are such that the monitored nuclear parameters (power, power distribu-tion, nuclear coefficients, etc) remain within their Technical

) Specification limits. Thus, it is concluded that the change does not i

involve a significant increase in the probability or consequences of j previously evaluated accident.

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2. Does the proposed license amendment create the possibility of a new

, or different kind of accident from any accident previously evaluated?

Response

The possibility of a new or different kind;of accident from any .

j previously evaluated has been considered and is not affected by this change. All of the fuel is contained in the fuel rod Which is of the

! same dimensions and designed to function the same as previous fuel.

l The existing new and spent fuel pool criticality analyses bound the

} changes observed. This change is mainly administrative in nature and

does not create the possibility of new or different kind of accident.

I 3. Does the proposed amendment involve a significant reduction in a

! margin of safety?

4 j Response:

j The margin of safety is maintained by adherence to other Technical i Specification limits and the FSAR Design Bases. The deletion of fuel l

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1 LCA 139 Page 4 of 5 1

rod weight limits in Technical Specifications Design Features Section 5.3.1 does not directly affect any safety system or safety limits. Because safety margins are maintained by other limiting Technical Specifications, the deletion of fuel rod weight limits in Technical Specification Design Features Section 5.3.1 will not affect the margin of safety.

In the April 6, 1983 Federal Register, NRC published a list of examples l of amendments that are not likely to involve significant hazards con-1 cern. Example No. 6 of that list applies to the deletion of the fuel rod weight limit Technical Specification, and states that,

". . . . a change which either may result in some increase to the probability or consequences of a previously-analyzed accident or may reduce in some way a safety margin, but where the results of the change are clearly within all acceptable criteria with respect to the system or component specified in the Standard Review Plan: for example, a change resulting from the application of a small refinement of a previously used calculational model or design method."

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