ML20195K150

Safety Evaluation Supporting Amend 110 to License DPR-3

ML20195K150
Person / Time
Site:	Yankee Rowe
Issue date:	06/17/1988
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20195K130	List: ML20195K124 ML20195K140 ML20195K150
References
NUDOCS 8806290356
Download: ML20195K150 (2)

Text

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, 4 o, UNITED STATES y }, NUCLEAR REGULATORY COMMISSION g E WASHINGTON, D. C 20555 g /SAFETYEVALUATIONBYTHEOFFICEOFNUCLEARRpCTORREGULATION

• • • $hPPORTINGAMENDMENTN0. 110 TO FACILITY CPERATING LICENSE N0. OpR-3

_ YANKEE ATOMIC ELECTRIC COMPANY YANKEE NUCLEAR p0WER STATION DOCKET NO.50-029 I INTRODUCTION Ry letter dated December 23, 1987 Yankee Atomic Electric Company (YAEC) or the licensee requested modifications to the Yankee Nuclear Power Station Technical Specifications (TS) governing control rod position indication. The changes 1 were requested to provide needed operational flexibility in the (TS), to )

eliminate an outdated reference to three-loop operation and to delete a reference to moveable incore detectors.

The licensee proposed to change the tolerance in TS 3.1.3.2. for the control rod position indication system from 3 inches to 8 inches. Primary control  !

rod position indicators consist of variable intensity Light Emitting Diodes 1 (LED)at3inchintervals. Each LED monitors a field of 3 inches of rod I inotion. Since the interval and the allowable tolerance are the same, a single l inoperable LED can cause the operator to perform unneeded control rod position adjustments. Expanding the tolerance to 8 inches would reduce the need for control red motion because an 8 inch interval is monitored by more than two LEDs; thus, control rod manipulation would not be forced unless three LEDs in a single row fail, j

EVALUATION  !

The original 3-inch limit in the Technical Specifications reflected a design  !

feature of the primary indication system and not the allowable operational j tolerance. There was no basis for requiring this extra conservatism, i.e.  ;

less than 8 inches.  !

Standard Technical Specifications (STS), on which the Yankee T.S. are patterned, call for identical operational tolerances for two closely associated specifications; Technical Specification 3.1.3.1 which governs control rod position and Technical Specification 3.1.3.2 which governs position indication. Accordingly, this change incorporates the criteria from Yankee Technical Specification 3.1.3.1 into Specification 3.1.3.2 and brings these two Specifications into agreement.

The actual tolerance in STS 3.1.3.1 and STS 3.1.3.2 is 12 steps. However, Yankee control rod position indications are read in inches rather than steps. l Therefore, 8 inches, which is approximately the step-to-inch conversion in the l standard Westinghouse design, was adopted and currently applies to Technical l Specification 3.1.3.1. This change incorporates the same criteria into YNPS l Technical Specification 3.1.3.2. 1 I

8806290356 DR 080617 ADOCK 05000029 PDR l

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Finally, as is currently stated in the basis to YNPS Technical Specificaticts,

"... control rod misalignment up to 8 inches from every other control rod in its group and for all control rod groups within their insertion limits, the hot chonnel factors will be well within the design limits."

Based on the above, we conclude that the change frorn 3 inches to 8 inches in TS 3.1.3.2 is acceptable.

The second change eliminates a reference to three-loop operation which was overlooked in NRC Amendment 88. The third change is a change to the wording for monitoring control rod location from "moveable incore detectors" to "incore detectors." With the recent insta116tiori of some fixed incore detectors, a fixed cetector may be the preferred choice for monitoring control rod location if it is the detector closest to the affected rod. The licensee subraltted data showing fixed detector signals versus time for control rod movement. It was evident from this data that the fixed incore detectors should be used to detect rod movement when these detectors are closest to the affected rod.

Based on the obove, we conclude the second and third changes are acceptable.

ENVIRONMENTAL CONSIDERATION An Environmental Assessment for this proposed action was published in the Federal Recister on June 17, 1988, (53 FR 22752). Therein, it war determined ihat tee 56p6sid changes will r,ot have a significant environmental impact because they will not increase the probability or consequences of accidents, alter the effluents which may be released offsite or significantly increase occupational radiation exposure.

CONCLUSION The stdff 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 end security or to che health and safety of the public.

M90WLEDGEMENT Principal Contributors: Margaret Chatterton, SRXB Morton B. Fairtile Dated: June 17, 1988 l

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