ML18139B052

LER 81-004/03L-0:on 810107,reactor Trip Breaker a Failed to Open.Caused by Sporadic Failure of Under Voltage Device Due to Missing Bushing.Under Voltage Device Replaced

ML18139B052
Person / Time
Site:	Surry
Issue date:	01/30/1981
From:	Joshua Wilson VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML18139B048	List: ML18139B047 ML18139B049 ML18139B050 ML18139B051 ML18139B052 ML18139B053
References
LER-81-004-03L, LER-81-4-3L, NUDOCS 8102050582
Download: ML18139B052 (2)

Text

NRC FORM 366 e

U.S. NUCLEAR REGULATORY COMMISSiON (7*77)

-LICENSEE EVENT REPORT CONTROL 8 LOCK:j,_ _*._1-------__,__ _,____l Q (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION!

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@II] I With Unit No, 2 at 1QQ% power, "A" Reactor Trip Breaker failed to open :while per -1 forming PT-8.1. T.S.4.1, table 4.1-1, requires PT-8.1 to be performed monthly. This

((ID event is reportable per T. S. 6. 6. 2. b. (2). The "B" Reactor Trip Breaker operated

[)))).!satisfactorily during the performance of PT-8.1. Therefore, the health and safety of

[QJ]J the public were not affected.

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JA sporadic failure of the under voltage device prevented the Breaker from openin~. A ITiiJ I missing bushing created excessive playin the UV device's linkai;e. Tbe 1rnder voltage o:::IIJ 1device was replaced and the breaker tested.

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0 NAME OF ?9E?ARER J, L. Wilson ?HONE: (804) 357-2941 Ext 210 *J 8 10 205 0 t;<t"1..-

ATTACHMENT 1 SURRY POWER STATION, UNIT 2 DOCKET NO: 50-281 REPORT NO: 81--004/03L--O EVENT DATE: 1-7-81

. TITLE of REPORT: REACTOR TRIP BREAKER FAILURE

1. DESCRIPTION of EVENT:

With Unit No .2 at 100% power, "Au Reactor Trip Breaker failed to open while performing PT-8.1 (Monthly Reactor Protection System Logic).

The "A" Reactor Trip bypass breaker was racked in at this time, The bypass breaker receives a trip signal from "B" train of RPS.

Technical Specification 4.1, table 4.1-1, requiresPT-8.1 to be performed monthly. This event is reportable per Technical Specification 6.6.2.b(2).

2. PROBABLE CONSEQUENCES and STATUS of REDUNDANT REQUIPMENT:

The power to the Control Rod Drive Mechanisms (CRDM~, is fed through two, series reactor trip breakers. Each trip breaker receives a trip signal from independent and redundant actuation trains. The tripping of either breaker will remove power from the CRDM's, thereby inserting the control rods into the core. The "B" Reactor Trip Breaker operated satisfactory during the performance of PT-8.1 and would have performed its intended function. Therefore, the health and safety of the public were not affected.

3. CAUSE:

The failure of "A" Reactor Trip Breaker was caused by a sporadic failure of the under voltage tripping device. The failure of a small retaining clip had allowed a bushing to be dislodged, thereby creating an excessive amount of play in the mechanical tinkage of the under voltage device.

4. IMMEDIATE CORR,E C.'I'IVE ACTION:

The "A" Reactor Trip Breaker was replaced and tested satisfactory.

5. SUBSEQUENT CORRECTIVE ACTION:

The under voltage device was replaced. The malfunctioning under voltage device was operated approximately 100 times in an attempt to duplicate the event. The under voltage device failed to function only once.

6. ACTION TAKEN TO PREVENT RECURRENCE:

Electrical Maintenance procedures will be revise

• d to a dd ress the inspection o[ the retaining devices.

7. GENERIC IMPLICATIONS:

.;Si:i,n,ce :th~e,.,\_Othe-r.d.m:de:r,.---31,ciJ*.t-age -.-devices -were inspected and failed to show any similar problems, this appe2rs to be an isolated case.