05000272/LER-1979-029-03, /03L-0 on 790320:during Channel Functional Test High Voltage Was Found to Be Low.Caused by Breakdown of Diode in High Voltage Power Supply.Diode Was Replaced & Channel Functional Was Completed

/03L-0 on 790320:during Channel Functional Test High Voltage Was Found to Be Low.Caused by Breakdown of Diode in High Voltage Power Supply.Diode Was Replaced & Channel Functional Was Completed

ML18078B227
Person / Time
Site:	Salem
Issue date:	04/19/1979
From:	Kapple A Public Service Enterprise Group
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML18078B226	List: 05000272/LER-1979-029, Forwards LER 79-029/03L-0 05000272/LER-1979-029-03, /03L-0 on 790320:during Channel Functional Test High Voltage Was Found to Be Low.Caused by Breakdown of Diode in High Voltage Power Supply.Diode Was Replaced & Channel Functional Was Completed
References
LER-79-029-03L, LER-79-29-3L, NUDOCS 7904240345
Download: ML18078B227 (3)

LER-1979-029, /03L-0 on 790320:during Channel Functional Test High Voltage Was Found to Be Low.Caused by Breakdown of Diode in High Voltage Power Supply.Diode Was Replaced & Channel Functional Was Completed

Event date:
Report date:
2721979029R03 - NRC Website

text

Report Number:

79-29/03L Report Date:

4/19/79 Occurrence Date:

3/20/79 Facility:

Salem Generating Station Public Service Electric & Gas Company Hancock's Bridge, New Jersey 08038 IDENTIFICATION OF OCCURRENCE:

Inoperable Nuclear Instrumentation Channel N-41 CONDITIONS PRIOR TO OCCURRENCE:

Operational Mode 1 Reactor Power 97%

DESCRIPTION OF OCCURRENCE:

While performing a functional test of power range nuclear instrumen-tation channel N-41, the high voltage was found to be 240 volts less than required.

Technical Specification 3.3.1.1 Action Statement 2 was implemented at 1155 hours0.0134 days <br />0.321 hours <br />0.00191 weeks <br />4.394775e-4 months <br /> and channel bistables were placed in the tripped condition.

The channel was repaired and returned to service at 1440 hours0.0167 days <br />0.4 hours <br />0.00238 weeks <br />5.4792e-4 months <br /> after the functional test was satisfactorily completed.

The Action Statement was terminated when the channel was returned to service.

DESIGNATION OF APPARENT CAUSE OF OCCURRENCE:

This occurrence was caus~d by the breakdown of a diode in the high voltage power supply.

ANALYSIS OF OCCURRENCE:

Technical Specification 3.3.1.l Action 2 requires that with the nuni-ber of operable channels one less than the total number of channels, startup and/or power operation may proceed provided the following conditions are satisfied:

a.

The inoperable channel is placed in the tripped condition within one hour.

b.

The minimum channels operable requirement is met; however, one additional channel may be bypassed for up to two hours for surveillance testing per Specification 4.3.1.1.

c.

Either thermal power is restricted to < 75% of rated thermal and the power range, neutron flux trip setpoint is reduced to

< 85% of rated thermal power within four hours; or, the quad-rant power tilt ratio is monitored at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

79042403~S

~---

LER 79-29/03L The channel bistables were immediately placed in the tripped condition.

The channel was returned to service within 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> and 25 minutes, therefore, Q.P.T.R. monitoring was not required.

CORRECTIVE ACTION

The diode was replaced and the functional test was completed satisfac-torily to verify channel operability.

FAILURE DATA:

Not Applicable Prepared By A. W. Kapple Manager -

SaJem Gnerating Station SORC Meeting No.

27-79

NRC,,!=OR¥~,!i l7!7J)-

U.S. NUCLEAR REGULATURY COMMISSION LICENSEE EVENT REPORT e CONTROL BLOCK: I I.

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(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATIONI 1

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L.ICENSEE CODE 14 15 L.ICSNSE NUMBER 25 26 L.ICENSE TYPE JO 57 CAT 58

~~~~~ L1J©I o l s I 01 o I o 12 I 7 I 2 101 o 13 I 2 lo I 119 IG)I o 14 111 91 7 I 9 IG) 60 61 DOCKET NUMBER 68 69 EVENT OATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES@

I During normal operation, while performing a channel functional test on N.I.

[£llJ I power range channel N-41, the high voltage was found to be low.

T/S 3.3.1.1 Action 2

!)))) I was implemented and the channel bistables were placed in the tripped condition.

The l:2:ill I channel was repaired and the functional satisfactorily completed within three hours

[£:()) ! and 25 minutes at which time the Action Statement was terminated.

Tnis is the second

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occurrence of this type.

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36 37 40 41 42 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS l P I 31 2 13 I 2s l This occurrence was caused by the breakdown of a diode in the high voltage power cr:IIJ I supply.

The diode was replaced and the channel functional was completed satisfactorily o::IIJ I to verify channel operability.

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