ML20214X339

Safety Evaluation Supporting Amend 100 to License DPR-3

ML20214X339
Person / Time
Site:	Yankee Rowe
Issue date:	12/01/1986
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20214X327	List: ML20214X324 ML20214X332 ML20214X339
References
NUDOCS 8612110071
Download: ML20214X339 (4)

Text

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1. ,4c e oq'o, UNITED STATES

[ " 3 ,, - l' ,g NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 5* E a%  !

% . .,. . f SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACT 0P PEGULATI0h SUPPORTING AMENCMENT N0.100 TO FACILITY OPERATING LICENSE N0. OPR-3 YANKEE ATOMIC ELECTRIC COMPANY YANKEE huCLEAR POWER STATION DOCKET NO.50-029

1.0 INTRODUCTION

By letter dated July 31, 1986, the Yankee Atomic Electric Company (YAEC) submitted a request for changes to the Yankee Nuclear Power Station Technical Specifications (TS). Additional information relating to this proposed change was submitted on October 8, 1986.

The amendment nodifies the TS regarding the minimum number of incore neutron detector thimbles required to be operable for the remainder of the present cycle (Cycle XVIII) operation. The measurement uncertainty is also increased when a reduced number of thimbles are operable.

2.0 DISCUSSION '.

The incore instrumentation system is required to be in operation to obtain a power distribution map at least once per 1000 effective full power hours. Factors are applied to the measured data prior to comparison with the TS operating limits. One such factor accounts for the uncertainty in the power distribution measurement. The Technical Specifications currently require a minimum of twelve incore instrumentation neutron detection thimbles with two per core quadrant to be operable. At present there art. 13 detectors operable and it is hoped that this number will remain operable for the rest of the cycle. The change was requested so that if two additional' detectors failed, the licensee would be able to complete the cycle. When fewer detectors are operable, a larger uncertainty factor is applied to the measurements.

On November 24, 1978, the minimum number of operable detectors was reduced from 17 to 12. At that time, the measurement uncertainty was increased from 5 percent to 6.8 percent. In 1982 during Cycle 15, after failure of a detector, only 12 detectors were operable. A Technical Specification change to allow use with fewer than 12 detectors was requested,

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l and approved on March 8, 1962 for the remainder of Cycle 15. The licensee repaired neutron detector thimbles during the next refueling outage and Cycle 16 began with 17 detectors operable. Two detectors failed in the following month. Two more detectors have failed since then. Because of the failure record of the incore detectors, the licensee is planning to replace inoperable detectors with fixed incore detectcrs during the next refueling. The Technical Specification change which Yankee Atomic Electric Company (YAEC) has proposed for the remainder of Cycle 18 is the same as the one approved for the remainder of Cycle 15 in 1982.

The specific changes requested by the licensee are:

(a) In TS 4.2.1.2d (Measurement Uncertainty for peak full power linear heat generation rate), change the requirement for the measurement uncertainty to be 6.8 percent when less than 17 and greater than or equal to 12 detectors are operable.

Presently, the TS provide for a 6.8 percent factor when less than 17 detectors are operable.

In addition, a provision would be added for a measurement uncertainty of 8 percent when less than 12, but greater than or equal to 9 detectors are operable.

(b) In TS 4.2.2.1 and 4.2.2.2 (Fq), similar changes as (a) above.

(c) In TS 4.2.3.2 (FA H), similar changes as (a) above.

(d) In TS 3.3.3.2 (Limiting Conditions fcr Operation - Incore Detection System), add an exception which states that for cycle 18, less than the 12 detectors (two per quadrant) can be operable provided that at least 9 detectors, with one per quadrant are operable.

(e) The basis would be changed also to correspond to these uncertainty factors.

3.0 EVALUATION In order to justify the change, YAEC has performed an analysis in which previous cycle full power measurements were reanalyzed with only 9 incore detector traces. The results were provided in the October 8, 1986 submittal. The data presented showed F F and LHGR values based on9detectortracesandthe8%uncertaintySe,rsui"thevaluesbasedon 13 (or more) detector traces and the 6.8% uncertainty. The least conservative values for the 9 incore detector traces were shown. All values using the 9 incore detector traces (and 8% uncertainty) were greater than or equal to the actual plant runs except for one Fo in which the 9 incore detector value was four tenths of one percent less.

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Since the F limit of 1.8 has a 10% maroin and the " measured" values were1.628 inn 1.622,thestaffconsiders'thisexceptioninsignificant.

The staff has reviewed YAEC's analysis and past operating history and agrees that a minimum of 9 incore detectors, with one per quadrant ano an uncertainty of 6% is appropriate for the remainder of Cycle 18.

Thus, the staff finds the Technical Specification change as proposed to be acceptable.

4.0 ENVIRONMENTAL CONSIDERATION

This amendment involves a change to a requiremer.t with respect to the installation or use of facility components located within the restricted 4 area as defined in 10 CFR Part 20. 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 end that there is no significant increase in individual or cumulative occ pational radiction exposure. The Commission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessaent need be prepared in connection with the issuance of this amendment.

5.0 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 the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.

6.0 ACKNOWLEDGEMENT Principal Contributor: M. Chatterton Dated: December 1,1986 a -

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f T Docket: File 150-029

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