05000369/LER-1982-010, Forwards LER 82-010/03L-0.Detailed Event Analysis Encl

Forwards LER 82-010/03L-0.Detailed Event Analysis Encl

ML20071H401
Person / Time
Site:	McGuire
Issue date:	02/19/1982
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20071H403	List: 05000369/LER-1982-010, Forwards LER 82-010/03L-0.Detailed Event Analysis Encl
References
NUDOCS 8203080404
Download: ML20071H401 (3)

LER-2082-010, Forwards LER 82-010/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3692082010R00 - NRC Website

text

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DUKE Powen Cod 1PANY ,.

I'owen Bust.nixo ace Sourn Cituncu Sruzzi, CnAHIDTTE, N. C. coa.m l J2 F E R 25 P1: 6*-

WI LLI AM O. PAR M E R, J R, vic, enemor , February 19, 1982 rca,-o,.cAac vo4 SYtaea PaoovcTeoM 373-4083 Mr. J. P. O'Reilly, Regional Administrator oo U. S. Nuclear Regulatory Commission " 9 Region II 101 Marietta Street, Suite 3100 O) plECElVED Atlanta, Georgia 30303 , ,

t MAR 0519826 21 Re: McGuire Nuclear Station Unit 1 84mfanus Docket No. 50-369 'O ECC /8 l Cu s i ro

Dear Mr. O'Reilly:

i

! Please find attached Reportable Occurrence Report R0-369/82-10. This report concerns T.S.3.1.3.2, "The shutdown and control rod position indication system and the demand position indication system shall be operable and capable of determining the control rod positions within + 12 steps." This incident was considered to be of no significance with respect to the health and' safety of the public.

l Ve trulyyours,[

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l h = = - _ Lb , p ' -

l William O. Parker, Jr.

l PEN /jfw Attachment t

cc: Director Records Center l Office of Management and Program Analysis Institute of Nuclear Power Operations E

U. S. Nuclear Regulatory Commission 1820 Water Place Washington, D. C. 20555 Atlanta, Georgia 30339 Mr. P. R. Bemis Senior Resident Inspector-NRC McGuire Nuclear Station 8203080404 820219 PDR ADOCK 05000369

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j DUKE POWER COMPANY McGUIRE NUCLEAR STATION REPORTABLE OCCURRENCE REPORT NO. 82-10 REPORT DATE: February 19, 1982 FACILITY: McGuire Unit 1, Cornelius, NC IDENTIFICATION: Continuing Failure of Digital Rod Position Indication l DISCUSSION: On January 20, 1982, while operating at 50% reactor power, all Digital Rod Position Indication (DRPI) for control rod K-8 was lost. The loss of both Data "A" and Data "B" channels required utilizing the movable incore detectors to monitor the control rod's position. The required core mapping procedure was continued until January 25, when the Data "B" channel was regained after a length of rod position detector cable was replaced.

EVALUATION: One data channel of control rad K-8 posiEion indication was repaired by replacing a "10 to 15 ft" length of cable extending from the DRPI coil stack to the associated bulkhead connector. This replacement is a partial completion of a modification which will change out all like DRPI cables and their bulkhead connectors (106 cables and connectors).

! The modification provides smaller diameter, more flexible cabling to the DRPI detectors, and strain relieving bulkhead connectors for the cables. The original cables were determined to be susceptible to conductor damage under flexure due to their own

< weight. They are approximately 1.5" in diameter and are difficult to maneuver when clearing the reactor head area is necessary. The replacement cabling is advertised as 300% more flexible and only about 0.86" in diameter. The replace-ment is expected to greatly alleviate the head area congestion problem.

Control rod K-8 position indication had performed at " half accuracy" since October 6, 1981, when one data channel failed as detailed in Reportable Occurrence Report R0-369/81-163. These previous incidents were erroneously evaluated as l common cause, detector coil failure, events.

During a plant shutdown period in November, 1981 cables serving inoperable DRPI detector channels for control rods K-8, H-6, G-13, and M-14 were replaced. All of the associated data channels, except Data "A" for K-8, functfoned properly after the replacement. Only Data "A" channel for. control rod K-8 remains as a suspected detector malfunction.

Presently, Data "A" for control rod K-8 and Data "A" for control rod L-3 remain inoperable. DRPI for control rod L-3 became inoperable after the November 1981 shutdown period.

SAFETY ANALYSIS: Inaccurate control rod position indication could lead-to control rod misalignment and uneven power distribution, a challenge to fuel rod integrity.

In this instance accurate position indication was maintained. Plant safety and the health and safety of the public were not affected.

t I

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l l

-Report No. 82-10 Page 2.

CORRECTIVE ACTION: During the planned outage in February, 1982 the completion of the modification is scheduled. Additionally, inspection of all DRPI detector coil stacks and the replacement of control rod K-8 detector coil stack are planned.

l The DRPI vendor, Westinghouse, will be involved in the inspection.

Replacement of DRPI cabling has proved effective in the correction of most DRPI

-problems.

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