ML20024F743

LER 90-023-00:on 901114,ESF Actuation & Feedwater Isolation Occurred in Response to Opening Condenser Steam Dump Valve. Caused by Operation of Steam Dump Sys in Steam Pressure Control Mode.Signal reset.W/901214 Ltr

ML20024F743
Person / Time
Site:	Beaver Valley
Issue date:	12/14/1990
From:	Noonan T DUQUESNE LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-023, LER-90-23, ND3MNO:3077, NUDOCS 9012170151
Download: ML20024F743 (6)

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

LER 90-023-00, 10 CPR 50.73.a.2.iv, " ESP Actuation -

Feedwater Isolation Due to Condenser Steam Dump Valve Response".

Very truly yours, A k d /)e m a L 60 0

T. P. lioonan General Manager 11uclear Operations al Attachment 9012170151 901214 26Qg PDR ADOCK 05000412 S PDR 1 "t .

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On 11/14/90, at 0001 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, with the Unit in Hot Standby, a surveillance test for reactor coolant system (RCS) resistance-temperature-detectors calibratien verifications were in progress. This test (RTD) requ ires the steam generators 1cvels at 56% and the operating crew to maintain a target RCS temperature of 450F. When the RCS temperature is within 5 degrees of the target, the test directs the operator to utilize the steam dump system to decrease the heatup rate. At 0639 hours0.0074 days <br />0.178 hours <br />0.00106 weeks <br />2.431395e-4 months <br />, the operator placed a demand signal on the steam dump system to initiate opening of the steam dump valves. This action resulted in a " swell" in all three steam generators, and a Feedwater Isolation (FWI) signal due to level in the 21B steam generator reaching the 75% setpoint value. The cause for this event was the calibration of the steam dump system. Three valves in the first bank of steam dump valves opened simultaneously rather than sequentially causing the rapid increase in steam flow. The FWI signal was reset and the feedwater containment isolation valves were reopened at 0642 hours0.00743 days <br />0.178 hours <br />0.00106 weeks <br />2.44281e-4 months <br />. The first bank of steam dump valves have boon recalibrated to open in a sequential mode. There were no safety implications as a result of this event. The feodwater containment isolation valves closed as designed upon receipt of  !

the FWI signal. All other components actuated by the FWI signal were not in service.

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sxs m, am e ,*u. eamac re nu omn DESCRIPTION OF EVENT on 11/14/90, at 0001 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, with The Unit in Hot Standby (operating Mode 3 , a surycillance test for reactor coolant system (RCS) resis)tance-temperature-detectors (RTD) calibration verification was in progress. This test requires the steam generators levels at 56% and the operating crew to maintain a target RCS temperature of 450F. When the RCS temperature is within 5 degrees of the targot, the test directs the operator to utilize the steam dump system to decrease the heatup rate. The steam dump system was in the " Steam Pressure Control Mode" which will normally allow operation of the first two banks of valve 9 valves) to maintain steam header pressure at a correspondin(g sotpoint determined by the operator. At the RCS temperature of 450F, a control interlock restricts operation of the steam dump va'.ves to three pressure control valves, which will respond to tne steam dump controller. At 0639 hours0.0074 days <br />0.178 hours <br />0.00106 weeks <br />2.431395e-4 months <br />, the operator placed a Jemand signal on the steam dump system to initiate opening of the steam dump valves. This action resulted in a " swell" in all three steam generators, and a Feedwater Isolation CFWI) signal due to lovel in the 21B steam generator reachang the 75%

setpoir.t value. The FWI signal resulted in closure of the foodwater containment isolation valves. The three pressure control valves opened simultaneously rather than sequentially causing the rapid increase in steam flow and the subsequent

" swell" of levels in the steam generators. The FWI signal was reset and the feedwater containment isolation valves were reopened at 0642 Murs. The Nuclear Regulatory Commission was notified of this Engineered Safety Features actuation at 0730 hours0.00845 days <br />0.203 hours <br />0.00121 weeks <br />2.77765e-4 months <br />.

CAUSE OF THE EVENT The cause for this event was the operation of the steam dump system in the steam Pressure Control Mode. Tha two banks of steam dump valves. including the three pressure control valves which are interlocked with RCS temperature, were calibrated to open simultaneously based on the magnitude ot controller output. This caused a rapid increase in steam flow and the subsequent " swell" of levels in the steam generators.

CORRECTIVE ACTIONS The following corrective actions have been or will be taken as a result of this event:

1. The FWI signal was reset and the feedwater containment isolation valves were reopened at 0642 hours0.00743 days <br />0.178 hours <br />0.00106 weeks <br />2.44281e-4 months <br />.

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2. The steam dump valves have been recalibrated to provide sequential opening versus simultaneous opening upon receipt of a demand signal.

REPORTABILITY $ '

This event was reported to the Nuclear Regulatory Commission at 0730 hours0.00845 days <br />0.203 hours <br />0.00121 weeks <br />2.77765e-4 months <br /> in accordance with 10CFR50.72.b.2.ii. This written report is being issued in accordance with 10CFR50.73.a.2.iv, an an event involving an Engineered oafety Features (ESP) system actuation.

PREVIOUS OCCURRENCES The following similar events involving feedwater isolations and steam dump system operation have been previously reported for Unit 2:

LER 87-009-00 " Inadvertent Feedwater Isolation" LER 87-017-00 " Inadvertent Feedwater Isolatior Due To A Procedural Deficiency" LER 90-021-00 " Inadvertent Feedwater Isolation Due To Repressurization Of Main Steam Header"

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D cambor 14, 1990 ND3MNO 3077 Page two cc Mr. T. T. Martin, Regional Administrator .

United States Nuclear Regulatory Commission l 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 Atlanta, GA 30339 G. E. Muckle, Factory Mutual Engineering 680 Anderson Drive #BLD10 Pittsburgh, PA 15220-2773 Mr. J. N. Steinmetz, Operating Plant Projects Manager Mid Atlantic Area Westinghouse Electric Corporation i Energy Systems Service Division Box 355 Pittsburgh, PA 15230 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

D3cemb3r 14, 1990 ND3M116: 3077 Pago three W. 11artley Management Analysis company 112671 High Bluff Drive San Diego, CA 92130-2025 J. M. Riddle NUS Operating Service Corporation Park West II Cliff Mino Road Pittsburgh, PA 15275

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