ML20024E912

LER 83-093/03L-0:on 830801,discovered full-in Indication on Core Display for Control Rod 34-47 Inoperable.Caused by Failed Switching Transistor on Data Memory Board 19.Data Memory Board replaced.W/830826 Ltr

ML20024E912
Person / Time
Site:	LaSalle
Issue date:	08/26/1983
From:	Diederich G, Winterhoff D COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
LER-83-093-03L, LER-83-93-3L, NUDOCS 8309070197
Download: ML20024E912 (3)

Text

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. _._: i l On August 1,19.83 at 2150 hours0.0249 days <br />0.597 hours <br />0.00355 weeks <br />8.18075e-4 months <br /> , durina LOS- AA-W1 ope rations di scovered that t h'e 9

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" Full In" indication on the core display for control rod 34-47 was inoperable. conse ;

,,, ; quences of this event were minimal since all remaining position indicators for control ;

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i. LER NUMBER: 83-093/03L-0 II. LASALLE COUNTY STATION: Unit I lit. ' DOCKET, NUMBER: ,050-373 . .,

IV. EVENT DESCRIPTION:

On August 1,1983 at. 2150 hours0.0249 days <br />0.597 hours <br />0.00355 weeks <br />8.18075e-4 months <br />, during the performance of LOS-AA-Wl, Technical Speci ficati.ons Weekly Surveillance, operations discovered, following a core display lamp test, that the " Full IN'_ indication on the core display for control red 34 47 was inoperable. The cont rol rod was " Full-IN' per Nuclear Engineer's Rod Secuence. Technicsl Speci fication 3.1.3.7.a.2 action s tategent .vas _ ente red .

V. PROSABLI CONSEC:UENCES OF THE OCCUBRENCE:

At the time of the occurrence, LaSalle Unit I was in ope rst ional condi tion 1, RUN mode, generating 2240 mwt. . Consequences of this event were minimal since all remaining position Indicators for control rod 34-47 were operable. Also, control rod 34-47 was the only control rod on the core display with an inop-

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'VII "CAUSE': '

The-inoperable "Ful1 In" indication for control . rod 34-47 was caused by the -

thermal destruction of a switching transistor on Data Memory Board #19 located i n fi le 3 on cont rol room pane l lH13-P603. This transistor was located on the memory data board to energize the " Full In" li ght when requi red by the circuit logic. Failure of this transistor was caused by normal usage. Ci r-cult design or application did not contribute to the failure.

Vll. CORRECTIVE ACTION: -

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In accordance wi th Technical Speci fication 3.1.3.7.a.2, ooe rations determined the control rod position by cycling the control rod to an operable posi tion i n d i ca to r. Work Request L26432 was generated and assigned to the Instrument Maintenance Department. They investigated the Data Memory Board #19 which controls core display light indication for cont rol rod 34-47 and discovered a failed switching transistor for the " Full In" circuit. The ins t rument Main-tenance Department replaced Data Memory Board #19 wi th a "like equivalent" r-c- the sic ercom "r ui! fn" iadicatio- #ce certrol -ed 3L 47 -#c -e=tored en Aucust 3, 1983 No problems have been encountered wirr the " Full In" indication for control rod 34 L7 cince, in order for operations to have an accurate representatien of cont rol rod core display indication (" Full IN', " Full Out". SCRAM. " Accu,ulator Trouble", etc.)

AIR 01-83-67059 was generated requesting a revision to LOS-AA-Si requi ring a core display lamp test be performed each shi ft.

Prepared by: D. Winterhof f L J

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- /'~ COmmORWealth Edison

e. [ = LaSalle County Nuclist Stition -

( -- y) -' Rural Route #1, Box 220 v

\ / Marseilles, Illinois 61341 N y Telephone 815/357-6761 August 26, 1983 James G. Keppler Regional Administrator Region lil U. S. Nuclear Regulatory Commission '

799 Roosevelt Road Glen Ellyn, IL 60137

Dear Sir:

Reportable Occurrence Report #83-093/03L-0 Docket #050-373 is being submitted to your office in accordance with LaSalle County Nuclear Power Station Techni-cal Speci fication 6.6.B.2,(b), conditions leading to operation in a degraded mode permitted by a limiting condition for operation or plant shutdown requi red by a limiting condition for operation, bb G. J. Diederich Superintendent LaSalle County Station GJD/GW/rg Enclosu re cc: Di rector of Inspection & Enforcement Di rector of Management Information & Program Cont rol U, S. NRC Document Management Branch INPO-Records Center File /NRC r- p SEP 1 1983 A 9 t I