ML19261E498

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Discusses LER 79-028/01P-0 on 790820:reactor Was Manually Tripped Following Trip of Main Feed Pump 1B Due to Low Net Positive Suction Head.Manual Trip Caused 1A & 1B 4kV Buses to Trip on All Reactor Coolant Pumps on Underfrequency
ML19261E498
Person / Time
Site: Beaver Valley
Issue date: 08/21/1979
From: Werling J
DUQUESNE LIGHT CO.
To: Grier B
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
707, NUDOCS 7908280422
Download: ML19261E498 (2)


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Shippingport, PA 15077 August 21, 1979 BVPS: JAW:707 Beaver Valley Power Station, Unit No. 1 Docket No. 50-334, License No. DPR-66 LER 79-28/OlP Mr. B. H. Grier, Director of Regulation United States Nuclear Reg'21 story Comzrission Region 1 631 Park Avenue King of Prussia, Pennsylvania 19406

Dear Mr. Grier:

In accordanc.e with Technical Specification 6.9.1.8.b, the following incident is reported. The report was discussed with Mr. D. A. Beckman at 1240 hotrs on August 20, 1979.

At 1446 hours0.0167 days <br />0.402 hours <br />0.00239 weeks <br />5.50203e-4 months <br />, the reactor was manually tripped from approximately 50% rated power following the trip of the 1B Main Feed Pump due to low net positive suction head. The 1A Condensate Pump was shutdown for cleaning of its strainer. The 10, Main Feed Pump h ' just been started and the 1A Pump secured to investigate a high bearing tempere.ure on the 1A Pump.

Upon initiation of the reactor trip, the operators performed the immediate n:anual actions folicwing a reactor trip and loss of normal feedwater. An operator, thinking that the gensrator output breakers were taking too long to trip, -

manually tripped them prius to the automatic trip which normally occurs 30 seconds af ter the reactor / turbine trip. Since the main generator was no longer tied to the system, frequency dropped on the 1A and IB 4KV Buses and all three reactor coolant pumps tripped on underfrequency (2 of 3 buses). The 1C and ID 4KV Buses were tied into the system aid did not experience the underfrequancy condition.

Thirty seconds af ter the turbine triy, the 1A and 1B Buses transferred to system power and the underfrequency condition cleared. Four minutes after the reactor trip, the 1C. Reactor Coolant Pump was started and forced flow returned to the reactor coolant system. All systems operated as designed and at no time was the health and safety of the public jeopardized.

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. Mr. B. H. Grier August 21, 1979 BVPS: JAW:707 Page 2 Corrective actions arm presently being considered by station management.

The results of this irvestigation will be provided in a followup report.

Very tru,1y yours,

~

Wale J. A. Werling Superintendent ec: Director Of Management & Program Analysissp/

United States Nuclear Regulatory Commission

  • Washington, D. C. 20555 D. L. Wigginton, BVPS Licensing Project Manager United States Nuclear Regulatory Commission Washington, D. C. 20555 D. A. Beckman, Nuclear Regulatory Commission, King of Prussia, PA G. A. Olson, Secretary, Prime Movers Committee - EEI 202l 137

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