ML20086S424

AO-S2-74-02:on 740413,when Unit Tripped Per Blackout Test Procedure,Loss of Power Experienced on Bus Normally Feeding Charging Pump.Caused by Dust on Contacts & Incorrect Alignment.Contacts Cleaned & Aligned

ML20086S424
Person / Time
Site:	Surry
Issue date:	05/06/1974
From:	Stallings C VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
AO-S2-74-02, AO-S2-74-2, NUDOCS 8403010558
Download: ML20086S424 (6)

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VznoINIA ELECTRIC AND Powsa COMI'ANY pr Ricuxonn.VxmoxxrA 20201 !d 6- qlh JgM.k.

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. Hay 6, 1974 N o Mr. A. Giambusso Scrial t!o.120 Deputy Director fer Reactor Projects P0&M/JTB:c1w Directorate of Licensing Office of Regulation Docket t!o. 50-281 '

United States Atomic Energy Commission License !!o. DPR-37 Washington, D. C. 20545

Dear Hr. Giambusso:

Pursuant to Surry Power Station Technical Specification 6.6.B.1, the Virginia Electric and Power Company hereby submits forty (40) copics of an Abnormal Occurrence Report llo. AG-S2-74-02.

The substance of this report has been reviewed by the Station iluclear Safety and Operating Coxaittee and will be placed on the agenda for the next ma.eting of the System liuclear Safety and Operating Corani ttee.

Very truly yours,

. . .n Y3.R?.J/an:7 C.11. Stallings Vice President-Power Supply and Production Operations ,

r Enclosures 40 copies of A0-S2-74-02 cc: Mr. iiorman C. floseley, Director Region 11, USAEC Mr. Stanley Ragone f

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u ABt10RMAL OCCURRENCE REPORT REPORT NO. A0-S2-74-02 FAILURE OF SAFETY INJECTION / CHARGING PullP TO START DURING BLACK 0UT TEST SU-3.1A t

APRIL 18, 1974 DOCKET No. 50-281 LICENSE NO. OPR-37 SURRY POWER STATION VIRGINIA ELECTRIC AND POWER COMPANY p I. -

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1. INTRODUCTION  :

In accordance with Technical Specification 6.6.B.1 for Surry Power  ;

i Station, Operating License DPR-37, this report describes an abnormal  ;

occurrence which occurred on April 13, 1974. The Directorate of Regulatory Operations, Region 11, was notified on April 14, 1974.  ;

The occurrence reported herein is classifled as an abnormal occurrence t

pursuant to Technical Specification 1.0.l.6 which states that "An abnormal occurrence is defined as: Engineered safeguard system malfunction or other , component or system malfunction which rendered or could render the engineered safeguard system Incapable of performing its intended safety >

fun ct i on . "  !

The occurrence described herein involved a safety injection / charging  ;

pump which failed to start during a test simulating unit blackout conditions.

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SUMMARY

OF OCCURRENCE On April 13, 1974, at approximately 2140 hours0.0248 days <br />0.594 hours <br />0.00354 weeks <br />8.1427e-4 months <br />, the unit was operating at approximately 37 per cent of rated power. The load had been reduced to this power level in order to conduct a unit blackout test. Charging

, pump 2-CH-P-C was running with its control switch in the automatic mode.

The remaining two charging pumps, 2-CH-P-1 A and 2-CH-P-1B, were not running and their control switches were in the automatic mode. When the

_ unit was tripped in accordance with the unit blackout test procedure a loss of power was experienced on the bus normally feeding the charging pumps.

Upon sensing the reduction in voltage, the emergency diesel generators

. started at a preset voltage. Interlocking circuitry required a charging

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O pump per emergency bus to be started when power is restored to the bus by the emergency diesel generators. Charging pump 2-CH-P-1C restarted, but charging pump 2-CH-P-1B failed to start on sensing emergency bus under-voltage, as designed. Charging pump 2-CH-P-1A did not start, as designed, since the logic circuitry allows only one charging pump per emergency bus  !

to start on sensing undervoltage.

Ill. ANALYSIS OF OCCURRENCE _

Charging pump 2-CH-P-1B failed to start as required on undervoltage. l The investigation following the occurrence indicated that contacts 5 and 6 on undervoltage relay 27X2-2H2 had dust on them and were in' correctly aligned, thus preventing proper starting of charging pump 2-CH-P-1B.

The relay under discussion is seale'd, i .e. I t is protected from the environment by a glass cover with an appropriate sealing material and it has a lock seal to prevent unauthorized tampering. Since the relay does not receive routine use, Inleakage of air and dust particles into the covered relay allowed a sufficient glaze to form, in conjunction wi th misalignment, to prevent the contacts from functioning properly.

'l V. , CORRECTIVE ACTION TO PREVENT RECURRENCE The subject contacts were subsequently cleaned and properly aligned.

The pump was tested satisfactorily in the automatic mode. The remaining l undervoltage relays associated with the charging pumps were checked ,

I and found to be satisfactory. -j l

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. Th.ese undervoltage relays and contacts are normally checked annually for proper operation. It is felt that this is an isolated incident and l i that no additional corrective action is warranted. ,

V. ANALYSIS AND EVALUATION OF SAFETY IMPLICATION OF Tile OCCURRENCE  ;

1 The incident described herein occurred during a test to verify the }

t proper operation of equipment during a unit blackout. Actual conditions  ?

i requiring the use of the charging pump did not exist. In any event, {

charging pump 2-CH-P-1C functioned properly and would have provided the necessary protection, If It had been required.

Charging pump 2-CH-1P-1B, even though falling to start automatically ,

I i on undervoltage, could have been started from the control room by use ,

of its control switch in its " start" position. Contacts 5 and 6 only  ;

e affect starting on sensing undervoltage, and do not affect other functions of the charging pump. '

i Sued or: Information contained in " Safety Related Occurrences in

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Nuclear Facilities as Reported in 1972" published by the Nuclear Safety information Center, " dirt" has been a contributor to a number of abnormal i .

3 occurrences experienced by the industry. Several other instances of dirty contacts have been experienced at Surry Power Station, but these  :

have been on " exposed" relays. In an effort to alleviate the conditions

conducive to dirty contacts, emphasis has been placed on better house-I -

l keeping to reduce the probability of occurrence.

l VI. CONCLUSIONS The licensee concludes that:

1. The failure of safety injection / charging pump 2-CH-P-1B I to start was caused by dirty and misaligned contacts. -

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. ,. , 2. It is felt that this is an isolated incident and that no

! further action is warranted. l 3 The occurrence reported herein did not affect the safe operation of the station.

4.- The occurrence described herein did not adversely affect I the health or safety of the general public.

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