ML19327C265

LER 89-028-00:on 891016,while Replacing Faulty Circuit Board,Power Cable & Arcing Occurred at Terminal Connection, Resulting in Containment Ventilation Isolation.Caused by Inadequate Design.Longer Block Screw installed.W/891114 Ltr

ML19327C265
Person / Time
Site:	Vogtle
Issue date:	11/14/1989
From:	Hairston W, Odom R GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
ELV-00968, ELV-968, LER-89-028, LER-89-28, NUDOCS 8911220048
Download: ML19327C265 (5)

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,. k . Georgia Power Company J

. 333 Pedmont Avonuo os ", " Atlanta, Georgia 30308 E '

• Teleptone 404 520 3195

. Maang Address: ,.

• ' 40 tnverness Center Parkway -

- Post Off.ce Dos I?95 .

[ . Damingham, Alabama 35201.

J- 4 Telephone 205 868 5581 y_ tw Mminem entuc system W. G. Hairston, til 1' senior vce e,es, dent November 14, 1989 Nuclear Opotations ELV-00968 0052 Docket No. 50-425 U.. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C.- 20555.

Gentlemen:

V0GTLE ELECTRIC GENERATING PLANT

, . LICENSEE EVENT REPORTL ARCING-POWER CABLE LEADS TO CONTAINMENT VENTILATION ISOLATION In accordance with 10 CFR 50.73, Georgia Power Company.hereby submits the enclosed report related to an event which occurred on October 16, 1989.

Sincerely,.

. W. G. Hairston, Ill WGH,III/NJS/gm

Enclosure:

. LER 50-425/1989-028 xc: Georaia Power Company i Mr. C. K. McCoy i Mr. G. Bockhold, Jr. l Mr. P. D. Rushton Mr. R. M. Odom NORMS ,

U. S. Nuclear Reaulatory Commission l

-Mr. S. D. Ebneter, Regional Administrator  !

Mr. J. B. Hopkins, Licensing Project Manager, NRR  !

Mr. J. F. Rogge, Senior Resident Inspector, Vogtle i

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NM.'E TELEPHONE NUMBER ARE A COOL R. M. ODOM, NUCLEAR SAFETY AND COMPLIANCE 40 i 4 82,6 i 1 i3 r2 iOl1 l COMPLETE ONE LINE FOR EACH COMPONENT F AILURE DESCRIBED IN TMis REPORT (131 e CAUSE $YSTEM COMPONE NT Uh gf " IA "pg[f' CAUSE SYST EM COMPONENT "j g[ R$ ,TpA E

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SUPPLEMENTAL REPORT EXPECTED 1943 MONTH DAY YEAR YES 199 ven, tenatete LXPECTRO SUO491Ss10N OA ffl NO l l l ASSTs.ACT (Limte to f eat) apsces, i.e., opprosenesey hrssen answe asece typewerrten Anes /1948 On 10-16-89, a technician was preparing to replace a faulty circuit board in a Containment vent effluent radiation monitor panel. While performing this work, he contacted a power cable and arcing occurred at the terminal connection. The arcing resulted in power fluctuations at the Input /0utput circuit board which subsequently failed. This led to a Containment Ventilation Isolation (CVI) actuation at 0825 CDT. Control room operators verified that no abnormal radiation condition existed in the Containment building atmosphere and reset the appropriate valves and dampers and the CVI signal.

The cause of this event was an inadequate design. The screw on the radiation  ;

monitor terminal block was too short to adequately engage the threaded opening and provide a tight, permanent connection with the attached power cable. When '

the technician's hand contacted the cable, the connection was loosened and arcing occurred. This screw and a similar screw in Unit I have been replaced.

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i A. REQUIREMENT FOR REPORT l because an unplanned 1 This report is required per 10 CFR 50.73 (a)(2)(ivEngineered Safety Featura (E]

B. UNIT STATUS AT TIME OF EVENT At the time of this event, Unit 2 was operating in Mode 1 (Power Operation) at 100% rated thermal aower. Other than that described herein, there was no inoperable equipment w11ch contributed to the occurrence of this event.

C. DESCRIPTION OF EVENT On 10-16-89, an Instruments & Controls (I&C) technician was preparing to replace.a. faulty Analog-to-Digital circuit board in the Data Processing Module (DPM)' of the Containment vent effluent radiation monitor 2RE-2565. '

This. process involved setting the DPM in bypass and lifting the ESF actuation leads in order to avoid an inadvertent ESF actuation while work was in progress. As he began to lift the leads inside the DPM panel, the technician contacted other wires inside the panel and noticed arcing at one ,

of the panel's terminals to which the power cable connects. He tightened I the loose terminal leads but found that the DPM was internally cycling in t I and out of bypass. The technician then called to advise the control room of ,

the situation and he was told that a Containment Ventilation Isolation (CVI) had occurred.

The CVI occurred at 0825 CD1, and Train A valves and dampers moved to their proper positions. Train B valves and dampers were manually actuated and the i operators then verified that the radiation level in the Containment '

atmosphere was normal. They noticed that 2RE-2565 was cycling in and out of l bypass and began an investigatior.. Valves and dampers were returned to l their normal positions and the CVI signal was reset at 1412 CDT.  !

l D. CAUSE OF EVENT u 1. The cause of this event was an inadequate design. The screw on the DPM terminal block was too short to adequately engage the threaded oaening and provide a tight, permanent connection with the attached power caale. When the technician's hand contacted the cable, the connection was loosened and l arcing occurred. The arcing led to erratic power fluctuations which caused I an Input /0utput circuit board to fail. This circuit board failure started the bypass function cycling and was also responsible for initiating the l.

Train A actuation while it concurrently blocked the Train B automatic ,

I actuation from 2RE-2565. I g,o.. . . _ i-. - 2

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2. Contributing to the occurrence of this event is the limited work space available'inside the panel. Lifting ESF actuation leads is performed prior to beginning work that might cause an unexpected actuation on this monitor.

The wires inside the DPM panel are moved to lift appropriate leads, and this movement caused the actuation. A DPM bypass switch was engaged prior to the

• start of this event. However, its function is to prevent erratic software indications from affecting monitor operability and could not prevent power fluctuations from causing an actuation.

E. ANALYSIS OF EVENT Train' A compcnents functioned as designed to automatically isolate Containment ventilation. Control room operators reacted properly to 1 manually. actuate Train B components. Had an area radiation monitor detected .

a high radiation level Train B components would also have actuated  !

automatically. However, no abnormal radiation level existed. Based on l these considerations, there was no adverse effect to plant safety or to the '

health and safety of the public as a result of this event.

F. CORRECTIVE ACTIONS l

L 1. A longer DPM terminal block setew has been installed for radiation monitor L 2RE-2565 to avoid a recurrence of this event. A broadness review indicated L that the same terminal block screw deficiency existed for Unit I radiation '

monitor 1RE-2565. The equivalent terminal block screw for 1RE-2565 has also been replaced.

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2. The capability to block the ESF actuation signal while work is in progress could preclude the need to lift ESF signal actuation leads. Plant personnel e are reviewing the feasibility of insta!14g block switches.

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.G. ADDITIONAL INFORMATION

1. Failed Components:

Input / Output Circuit Board manufactured by Westinghouse Electric Corporation.-

Part # 2347837G01 2., Previous Similar Events: i There have been no previous CVI actuations due to loose electrical ,

connections.

3.. . Energy Industry Identification System Code:.

Radiation Monitoring System - IL  !

Containment Isolation Control System - JM e

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I J . NIC FOnM 3eeA 'U.S. GPo, 1988 5 20-563 r 00010 I

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