05000397/LER-1984-008, Revised LER 84-008-01:on 840128,suppression Pool Level Indicator & Pool Level Fell Below Tech Spec Limits.Caused by Simultaneous Loss of Control Room Indication & Operation of Loop a of RHR Sys.Indication Reenergized

Revised LER 84-008-01:on 840128,suppression Pool Level Indicator & Pool Level Fell Below Tech Spec Limits.Caused by Simultaneous Loss of Control Room Indication & Operation of Loop a of RHR Sys.Indication Reenergized

ML20090G980
Person / Time
Site:	Columbia
Issue date:	07/19/1984
From:	Martin J, Powers C WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF ADMINISTRATION (ADM)
References
LER-84-008, LER-84-8, NUDOCS 8407260033
Download: ML20090G980 (4)

LER-2084-008, Revised LER 84-008-01:on 840128,suppression Pool Level Indicator & Pool Level Fell Below Tech Spec Limits.Caused by Simultaneous Loss of Control Room Indication & Operation of Loop a of RHR Sys.Indication Reenergized

Event date:
Report date:
3972084008R00 - NRC Website

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Suppression Pool Level Outside Technical Specification Limits

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Revision 0 to LER 008, issued on February 24, 1984, reported a failure of a suppression pool level indicator (CMS-LR/PR-4) and the subsequent determination that suppression pool level was below the Technical Specification limits.

The purpose of this supplemental report is to address the loss of water in the suppres-sion pool during the event due to an inadequate valve lineup. As previously reported, Technical Specifications (4.5.3.1) requires the suppression pool level to be maintained at a minimum of 30 feet 9-3/4 inches. Actual level was determined to be approximately 30 feet 5 inches and was verbally reported to the NRC pursuant to 10CFR50.72(2)(iii)(D).

i (It should be noted that the original report incorrectly stated that the Plant was in mode 5 at the time of the event. The Reactor vessel head was tensioned on January 26, 1984, two days preceding the event, and the nede switch was transferred from refueling to shutdown.)

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• ' LICENSEE EVENT REPORT (LER) TEXT CONTINUATION movio ous =o mo-om EXPtRES. 8/31/85 4

FAcluTV NAME lu DOCKET NUMSER (21 ggn gyuggR (6, PAGE138 TEAR M*M'b  :

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Of 1 d2 F Ol 3 Plant Operating Conditions l

_.a). Power Level -

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b) Operating Mode -

4 (Prior to Initial Plant Heatup)

Event During normal shutdown conditions prior to initial power operation, only one channel of suppression pool level indication was available. The suppression pool level recorder was ~ inadvertently de-energized when the 120 VAC power supply breaker feeding it was I opened at 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br /> on January 27, 1984. The Control Room recorder was not noted as out of service until 1000 hours0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br /> on January 28, 1984. The level decrease occurred during this 20 hour2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> period. The NRC was notified at 1340 hours0.0155 days <br />0.372 hours <br />0.00222 weeks <br />5.0987e-4 months <br /> on January 28, 1984 pursuant to ,

10CFR50.72(2) (iii )(D) . '

When pool level indication was returned to service it was noted that condensate had ac-cumulated in the reference leg of the transmitter causing an incorrect level indication in the Control Room. The cause of the violation was the result of a simultaneous loss of suppression pool level indication in the Control Room and the operation of the ' A' loop of the Residual Heat Removal (RHR) system in shutdown cooling while the 'B' loop was also lined up for shutdown cooling but was not in service. This configuration of the Residual Heat Removal system, as specified in the then existing plant procedure, provided a flow path to remove water from the wetwell through the inactive loop and inject it into the vessel where normal Reactor vessel level control actions discharged the water to the condenser hotwell. The flow path resulted from an incorrect cross-tie t valve lineup which allowed suppression pool water to flow through the waterleg pump, RHR-P-3, to the discharge of RHR-P-2B back through the discharge check valve, RHR-V-31B, to the pump suction and into the A RHR system when RHR pump B shutdown cooling suction valve RHR-V-6B was left open. This lineup produced insufficient differential pressure to adequately backseat the RHR B discharge check valve.

, Immediate Corrective Action j

The Control Room indication was reenergized, a local measurement of the suppression pool level was taken, water was drained from the reference leg of the tre.nsmitter to provide l i accurate level indication and water level was restored in the suppression pool.

Further Corrective Action The cause of the water loss was not identified until a similar event occurred approxi-  !

mately two weeks later. The corrective action taken after the recurrence was to close ,

the Residual Heat Removal Pump suction cross-tie valve for the inactive loop when both  !

loops are lined-up for ' shutdown cooling. A subsequent revision to the RHR system pro-cedure was issued to specify the correct valve lineup. When not in the shutdown cooling mode, the Residual Heat Removal trains are maintained in their normal Low Pressure Cool-ant Injection mode lineup.as required by Plant procedure.

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01 1 0l3 F Ol 3 TEXT t# #iore apoco a regered, ese esseoriet #Ac Arm JsM'sJ ith To eliminate the level indication complication, the suppression pool level recorders were marked to show Technical Specification upper and lower level limits. A list of loads receiving power from each circuit breaker is being developed and the suppression pool level transmitter's reference legs are periodically drained.

Safety Significance There were no safety consequences as a result of this event. The reactor was in cold shutdown condition with the fuel having an insignificant fission product inventory.

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r Washington Public Power Supply System P.O. Box 968 3000GeorgeWashingtonWay Richland, Washington 99352 (509)372-5000 Docket No. 50-397 July 19,1984 Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

NUCLEAR PLANT NO. 2 LICENSEE EVENT REPORT NO. 84-008-01

Dear Sir:

Transmitted herewith is Licensee Event Report No. 84-008-01 for WNP-2 Plant. This report is submitted in response to the report requirements of 10CFR50.73 and provides supplemental information to LER 84-008, Rev. O.

Very truly yours, J. D. Ma n (M/D 927PI)

WNP-2 Plant Manager JDM:mm

Enclosure:

Licensee Event' Report No. 84-008-01 cc: Mr. John B. Martin, Adninistrator Region V, Office of Inspection and Enforcement -

U.S. Nuclear Regulatory Commission 1450 Maria Lane Walnut Creek, California 94596 Mr. A. D. Toth, NRC Resident inspector (901 A)_ .

Ms. Dottie Sherman American Nuclear Insurers

.The Exchange Suite 245 270 Farmington Ave.

Farmington, CT 06032 4

+W 4

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