05000280/LER-1978-032-03, /03L-0 on 781011:heat Tracing Circuit Faults Had Occurred as a Result of Boric Acid Incursion.Faults Repaired & Circuit Current Verified

/03L-0 on 781011:heat Tracing Circuit Faults Had Occurred as a Result of Boric Acid Incursion.Faults Repaired & Circuit Current Verified

ML18113A604
Person / Time
Site:	Surry
Issue date:	11/06/1978
From:	Baucom T VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML18113A601	List: 05000280/LER-1978-030, Forwards LER 78-030/03L-0, 78-031/03L-0, 78-032/03L-0, 78-033/03L-0 05000280/LER-1978-030-03, /03L-0 on 781009:w/unit at Rated Pwr,Charging Pump Component Cooling Water Pump Btripped.Pump Tripped on Overcurrent.Caused by Corrosion Damage to Motor Bearings. Pump & Motor Rebuilt & Reinstalled 05000280/LER-1978-032-03, /03L-0 on 781011:heat Tracing Circuit Faults Had Occurred as a Result of Boric Acid Incursion.Faults Repaired & Circuit Current Verified 05000280/LER-1978-033-03, /03L-0 on 781015:heat Tracing Circuit Failed. Caused by Old Boric Acid Buildup & Penetration of Heat Leakage
References
LER-78-032-03L-01, LER-78-32-3L-1, NUDOCS 7811090217
Download: ML18113A604 (3)

LER-1978-032, /03L-0 on 781011:heat Tracing Circuit Faults Had Occurred as a Result of Boric Acid Incursion.Faults Repaired & Circuit Current Verified

Event date:
Report date:
2801978032R03 - NRC Website

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I With the unit at ra_ted power, routine surveillance of heat tracing systems disclosed [QJ}J I possible fault$ in circuits 23A (~anel 1), 23A (Panel 2) and circuits 24D (Panel 1),

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I 24D (Panel.2).

Each is a paired redundant circuit.

Circuits 23A are to the outlet

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I piping from the boron injection tank and circuits 24D are recirc bypass piping to

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jHeat traci-5 circuit £2'.ll.ts had occurred as a result of boric acid incursion.

The [III] I faults~~-= ~=~ai~ec. 2::.d circuit currents verified.

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Surry Power Station, Unit 1 Docket No: 50-280 Report No: 78-032/0JL-0 Event Date: 10-11-78 Heat Tracing Low Current

1.

Description

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With the unit in normal operation at rated power, routine surveillance indicated that Heat Tracing Circuits 23A (Panels 1 and 2) and Circuits 24D (Panels 1 and 2) were operating at less than the currents specified in the surveillan~e document.

Each of the circuits in question are paired redundant circuits.

Circuits 23A serve the outlet piping from the Boron Inject~on tank and circuits 24D serve the Boron Injection tank recirc piping.

An orderly sp.utdmin was initiated at approximately Q940. _

Concurrently, an investigation for faulty heat trace tape was initiated.

Relief valve 1857 in the Boron Injection Tank outlet piping had indications of leakage and boric acid attack on the tape causing the fault;

thus, causing the low current in circuits 23A.

Valve l-SI-77 in the Boron Injection tank recirc piping was found coated with boric acid crystals indicating a leak in the past.

Again, boric acid had attacked the tape causing the fault.

Repairs to the tapes were completed and the circuit currents verified. Unit rampdown was terminated at 1430 and the unit was returned to rated power.

The event constitutes a condition contrary to Technical Specification 3.2.B.5 and is reportable in accordance with Technical Specification 6.6.2.b.(2).

2.

Probab~e Consequences/Status of Redundant Systems:

1:.= all t:i:;::es during the event, temperatures in the Boron Injection tank outlet ?i?ing and recirc piping were maintained as required.

There were two oper2b~2 =low ?2t2s for boric acid to the reactor at all times.

Accordingly, the be=~t:i ar2d s:::_£:::ty of the public were not affected.

3.

Cause

The re.ducetl currents was the result of boric acid damage to the heat tapes i~ the sec~ions of piping.

In turn, the boric acid damage was the_

result of leakcge from a valve fitting in the piping which deposited boric acid cr.rstals.

4.

Innnediate Corrective Actions:

Valve fitting leaks were repaired, piping and fittings*cleaned and damaged heat tracing replaced.

5.

Scheduled Corrective Action:

The problem was corrected immediately and no further action is deemed necessary.

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{Attachment, Page 2 of 2)~

Surry Power Station, Unit 1 Docket*No: 50-280 Report No: 78-032/031-0 Event Date: 10-11-78 Heat Tracing Low Current

6.

Actions Taken to Prevent Recurrence:

Continuous surveillance is maintained on the heat tracing systems required for unit operation.

No additional action is considered necessary.

7.

Generic Implications:

This failure, as with others in the system, is considered random since no specific circuit or panel has exhibited repeated failure.