ML18139B385

LER 81-009/01T-0:on 810522,Westinghouse Identified Potential Sys Interaction Involving Vol Control Tank Level Control Sys & Charging Pumps.Caused by Design Criteria Misinterpretation.Procedure Mods Will Be Made

ML18139B385
Person / Time
Site:	Surry
Issue date:	06/05/1981
From:	Joshua Wilson VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML18139B384	List: ML18139B383 ML18139B385 ML18139B386 ML18139B387 ML18139B388 ML18139B389
References
LER-81-009-01T, LER-81-9-1T, NUDOCS 8106090523
Download: ML18139B385 (3)

Text

NRC FORM 366 (7-77)

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LICENSEE EVENT REPORT 10

. C L E A R REGULATORY COMMISSION (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATIONI LU2]

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VENT D:SCRIPTION AND PROBABLE CONSEQUENCES @

I Westinghouse has identified a potential system interaction concern involving the

[£ID I volume control tank (VCT) level control .system and charging pumps. A postulated

[ill] I failure of the VCT level control system,' without operator intervention, could lead

[QJ]J I to a loss of suction fluid for the charging pumps. Numerous visual and audible

[IJTI / indications are available to the operator to pemit the termination of this

[£JJJ jpostulated event. The health*and safety of the public were not affected. This

• [II)) 1 event is reportable per T.S.- 6.6.2.a(9).

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The cause of this concern appeared to be one of design criteria interpretatio1J..,_~__Jb~

operating staff has been alerted to this potential problem and rhe _consequences.

IT))] I Mi.nor. modifications to Unit No. l and 2 pr_ocedures wi 11 be made to provide additional!

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ATTACHMENT 1 SURRY POWER STATION, UNIT NO.

DOCKET NO: 50-280 REPORT NO: 81-009/017-0 EVENT DATE: 05-22-81 TITLE OF EVENT: VCT LEVEL SYSTEM DESIGN PROBLEM

1. DESCRIPTION OF EVENT:

Westinghouse has identified a potential system interaction involving the volume control tank (VCT) level control system and the charging pumps.

A postulated failure (failed high) of the VCT level control system, without operator intervention, could lead to a possible loss of suction fluid for the charging pumps.

This is reportable per Tech. Spec. 6.6.2.a (9).

2. ~ PROBABLE CONSEQUENCES arid STATUS of REDUNDANT EQUIPMENT:

The VCT is the normal supply to the charging pumps. The RWST is the alternate and accident supply to the charging pumps. If VCT level. transmitter (LT-115) failed high, letdown* to the VCT would be diverted to the Primary Drain Tank.

The auto~attc mak~ up to the VCT and the automatic transfer to the RWST, on

.. *VCH.. Low*-low level, would not_be funq,ional; Throughout this event, numerous

,set.onda ry *ind i caFons (VCT pressure, charging pressure and f 1ow) and a 1arms would be available to the operator for system evalua~ion. In addition, redundant VCT level indication (Ll-112), located near the VCT, would be available.

Westinghouse has indicated that the operator would have approximately 10 minutes to transfer the charging pump suction from the VCT to the RWST or initiate other appropriate corrective actions to prevent possible damage to the operating charging pump.

The failure of the VCT level control system will not prevent the manual transfer of charging pump suction* to the RWST or the automatic transfer to the RWST during an accident.

Since num~r6us visual and audible indications are available to the operator to permit the termination of this postulated event, the health and safety of the public would not be affected.

3. CAUSE:

The cause . of this.cconcern .appeared to be one of design criteria interpretation.

4. IMMEDIATE CORRECTIVE ACTl'ON:

The operating staff was alerted to this potential problem and the consequences.

ATTACHMENT 1 (continued)

SURRY POWER STATION, UNIT NO.

- DOCKET NO: 50-280 REPORT NO: 81-009-017-0 EVENT DATE: 05-22-81

5. SUBSEQUENT CORRECTIVE ACTION:

A review of station procedures was conducted, and as a result, minor modifi-cations (clarifications) will be made. )n addition, the postulated event, the consequences and the required corrective actions will be included in the operator's training/retraining program.

6. ACTION TAKEN TO PREVENT RECURRENCE:

At this time, none is deemed necessary.

7. GENERIC IMPLICATIONS:

This concern is generic to both Unit No. 1 and 2, therefore, Unit No. 2 procedures will be modified .

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