05000369/LER-1981-144, Forwards LER 81-144/03L-0.Detailed Event Analysis Encl

Forwards LER 81-144/03L-0.Detailed Event Analysis Encl

ML20031B258
Person / Time
Site:	McGuire
Issue date:	09/21/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20031B259	List: 05000369/LER-1981-144, Forwards LER 81-144/03L-0.Detailed Event Analysis Encl 05000369/LER-1981-144-03, /03L-0:on 810822,digital Rod Position Indication Control Board Display Panel Began Flashing Between Steps 222 & 228 for Rod G-13 in Shutdown Bank B.Cause Could Not Be Determined.Bank B Declared Inoperable
References
NUDOCS 8110010121
Download: ML20031B258 (3)

LER-1981-144, Forwards LER 81-144/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3691981144R00 - NRC Website

text

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DUKE Powen COMPANY Powra Burutwe 422 SouTa Cauncu Sinzzi, CaAntoTTE, N. C. asa4a WI LLIAM Q. PAR K ER. J R.

st$ ".*o'o'uEo September 21, 1981

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Mr. J. P. O'Reilly, Director 3g g/

U. S. Nuclear Regulatory Commission s

Region II fff h,

101 Marietta Street, Suite 3100 g

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SEP3ogggy,{'u_

2 Atlanta, Georgia 30303 3; u.a., % %

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"'4 m Re: McGuire Nuclear Station Unit 1 sg Docket No. 50-369 p

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Dear Mr. O'Reilly:

Please find attached Reportable Occurrence Report R0-369/81-144. This report concerns I.S.3.1.3.5, "All Shutdcwn Rods shall Be Fully Withdrawn." This in-cident was considered to be of no significance with respect to the health and safety of the public.

V ry trtly your,

M m tb-William O. Parker, J.

PBN/smh Attachment ec: Director Mr. Bill Lavallee l

Office of Management and Program Analysis Nuclear Safety Analysis Center n gulatory Commission Post Office Box 10412 l

U. S. Nuclear e

Washington, C. C.

20555 Palo Alto, California 94303 Ms. M. J. Graham Resident Inspector-NRC McGuire Nuclear Station I

SSP SN i

8110010121 810921 [I

l PDR ADOCK 05000369 S

FDR

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I McGUIRE NUCLEAR STATION REPORTABLE OCCURRENCE i

REPORT NUMBER:

81-144 REPORT DATE:

September 21, 1981 OCCURRENCE DATE: August 22, 1981 FACILITY: McGuire Unit 1; Cornelius, N.C.

IDENTIFICATION OF OCCURRENCE:

Shut-down Bank B was declared inoperable due to the inability of instrumentation to indicate the exact position of rod G-13.

CONDITIONS PRIOR TO OCCURRENCE: Mode 2, Start-up, during zero power physics testing.

DESCRIPTION OF OCCURRENCE:

On August 21, the LED's which indicate rod position on the Digital Rod Position Indication (DRPI) Control Board Display Panel began to flash between steps 222 and 228 (fully withdrawn) for rod G-13 in shut-down bank B.

Inspection of the logic cabinets for the rod control system did not re-veal any problems. Since the exact position of rod G-13 could not be determined, shut-down bank B was declared inoperable. This was repor~able pursuant to Tech-nical Specification 3.1.3.5.

APPARENT CAUSE OF OCCURRENCE:

It could not be determined why rod G-13 was not fully withdrawn.

ANALYSIS OF OCCURRENCE: The DRPI employs two sets of alternating coils,. Data 1

A and B, wh3ch each of the control or shutdown rods pass through. As the rods are being withdrawn, LED's indicating rod position are energized by the corre-sponding Data A or B coils. A group step counter also indicates the number of steps the rods are withdrawn.

In this incident rod G-13 was actually located at step 225 in the middle of a data coil. When the rod reached this point, the LED for step 228 energized and the LED for step 222.deenergized.

However, due to normal coil heating or possibly vibration caused by the cycling of other con-l trol rods, the LED indicating lights began flashing,at steps 222 and 228. When shut-down bank B (four rods including G-13) was fully withdrawn previously, the group step counter indicated the bank B position at step 228. Since the exact position of rod G-13 could not be determined, Operations personnel declared shut-down bank B inoperable. Using the procedure, " Inoperable Control Rod," they withdrew G-13 to step 231 which is the==v4==

the rods can be physically with-drawn and then inserted it to step 228.

Shutdown bank B was declared operable on August 22.

During the week prior to the incident, zero power physics tests were performed in which individual control rods were moved.

However, no individual shut-down rods were moved, only groups of shutdown rods were operated. Therefore, it could not be determined why rod G-13 was three steps below the other three rodrs in shut-down bank B.

E

Rep:rt Numbn-81-144 Page 2

SAFETY ANALYSIS

Since rod G-13 was only three steps from being fully withdrawn, it essentially had no significant influence on the core and thus, safe operation and the health and safety of the public were not affected.

C')RRECTIVE ACTION: Shut-down rod G-13 was withdrawn three steps to step 228 (fully withdrawn) using the procedure, " Inoperable Control Rod."

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