ML20043G577

LER 89-017-02:on 891218,atmospheric Steam Relief Valve C Opened to Lower MSIV C.Caused by Swell Phenomena Experienced After Opening MSIV C.Feedwater Isolation Signal Reset. W/900615 Ltr

ML20043G577
Person / Time
Site:	Beaver Valley
Issue date:	06/15/1990
From:	Noonan T DUQUESNE LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-017, LER-89-17, ND3MNO:2087, NUDOCS 9006200451
Download: ML20043G577 (5)

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Beaver Valley Power Station, Unit No. 1 Docket No. 50-334, License No. DPR-66 LER 89-017-02 United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Gentlemen:

In accordance with Appendix A, Beaver Valley Technical Specifications, the following Licensee Event Report is submitted:

LER 89-017-02, 10 CFR 50.73.a.2.iv, "Feedwater Isolation -

Engineered Safety Features (ESP) Actuation".

This revision is being issued to substantiate the original root cause evaluation following additional engineering analyses of the event parameters.

Very truly yours, T. P. Noonan General Manager Nuclear Operations s1 ,

Attachment S

9006200451 900615 PDR ADOCK 050003Q4 PDu

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June 15, 1990

.ND3MNO 2087 Page two cc: Mr. T. T. Martin, Regional Administrator United States Nuclear Regulatory Commission Region 1 ,

475 Allendale Road King of Prussia, PA 19406 C. A. Roteck, Ohio Edison 76 S. Main Street Akron, OH 44308 Mr. A. DeAgazio, BVPS Licensing Project Manager United States Nuclear Regulatory Commission Washington, DC 20555 J. Beall, Nuclear Regulatory Commission, BVPS Senior Resident Inspector Larry Beck Cleveland Electric 6200 Oak Tree Blvd.

Independence, Ohio 44101 INPO Records Center Suite 1500 1100 circle 75 Parkway l Atlanta, GA 30339 l G. E. Muckle, Factory Mutual Engineering, Pittsburgh 3 Parkway Center Room 217 Pittsburgh, PA 15220 Mr. J. N. Steinmetz, Operating Plant Projects Manager Mid Atlantic Area Westinghouse Electric Corporation Energy Systems Service Division t Box 355 l

Pittsburgh, PA 15230 American Nuclear Insurers

, c/o Dottie Sherman, ANI Library The Exchange Suite 245 270 Farmington Avenue Farmington, CT 06032 Mr. Richard Janati Department of Environmental Resources P. O. Box 2063 16th Floor, Fulton Building Harrisburg, PA 17120 Director, Safety Evaluation & Control Virginia Electric & Power Co.

P.O. Box 26666 One James River Plaza Richmond, VA 23261

'Jun3 15, 1990

.ND3MNOt2087

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A i . A c t m , ,, . . , . . . .... . . . .. . . . , n . i On 12/18/89, with the Unit in Hot Standby (Operating Mode 3),

operations personnel opened the "C" Atmospheric Steam Relief Valve to lower the "C" steam generator pressure to facilitate opening of the "C" Main Steam Isolation Valve (MSIV). This is required due to an interlock which prevents the valve from opening on a high differential pressure. Steam Generator level in the "C" Steam Generator (SGC) was indicating 55 percent (%) on the narrow range scale. Upon opening of the "C" MSIV, at 1323 hours0.0153 days <br />0.368 hours <br />0.00219 weeks <br />5.034015e-4 months <br />, steam generator level in SGC swelled to 75% causing a Feedwater Isolation (FWI) Signal. This caused the closure of the feedwater containment isolation valves. Operations personnel reset the FWI signal. An investigation determined that the cause on this event was swell phenomena, due to the plant conditions and the reactor coolant system temperature decrease experienced after the "C" MSIV was opened. There were no safety implications due to this event.

Feedwater Isolations caused by Hi-Hi Steam Generator Levels are analyzed in Beaver Valley Unit 1 UFSAR section 14.1.9, " Excessive

. Heat Removal Due to Feedwater System Malfunctions."

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DESCRIPTION OF EVENT

! On 12/18/89, with the Unit in Hot Standby (Operating Mode 3),

operations personnel slowly opened the "C" Atmospheric Steam Relief Valve to lower the "C" steam generator pressure to facilitate opening of the "C" Main Steam Isolation Valve (MSIV).

An electrical interlock in the circuit prevents opening of the l

MSIV unless there is less than or equal to five (5) pounds differential pressure across the valve. Steam Generator level in the "C" Steam Generator (SGC) was-indicating 55 percent (%) on the narrow range scale. Upon opening of the "C" MSIV, at 1323 hours0.0153 days <br />0.368 hours <br />0.00219 weeks <br />5.034015e-4 months <br />, steam generator level in SGC swelled to 75%. This was sensed by two of three (Channels II and III) narrow range level transmitters causing a Feedwater Isolation (FWI) Signel. The FWI signal caused the closure of the feedwater containment isolation valves.

Operations personnel reset the FWI signal and restored the plant l to pre-FWI conditions.

l l CAUSE OF THE EVENT An initial analysis determined that the feedwater isolation signal was due to the " swell" phenomena experienced after the opening of the "C" MSIV. Further calculations and comparison to a previous Steam Generator level / pressure transient, using the pre- and post-FWI reactor r,oolant system temperatures, feedwater flows, steamline flows Gnd pre- and post-FWI steam generator levels, confirmed that the 20% increase in Steam Generator level was due to the " swell" phenomena, l Under normal plant conditions in Hot Standby, Steam Generator level is maintained at its programmed level of 33%. Prior to this event, Steam Generator had been increased to 55% to support an ongoing Reactor Coolant System Temperature Sensor cross calibration test.

CORRECTIVE ACTIONS operations personnel reset the feedwater isolation signal and restored the plant to pre-FWI conditions.

Safety Analysis i

There were no safety implications due to this event. The only components at that time to be actuated by the Feedwater Isolation Signal were the three Feedwater inlet containment isolation valves to the Steam Generators, which responded properly (stroked closed)

, to the Feedwater Isolation signals. Auxiliary Feedwater remained available throughout this event. Feedwater Isolations due to Hi-Hi Steam Generator Levels are analyzed in Beaver Valley Unit 1 UFSAR section 14.1.9, " Excessive Heat Removal Due to Feedwater System Malfunctions.

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