ML19309G361

LER 80-014/03L-0:on 800402,during Routine Reactor Startup, Operators Observed Frequency Drifting on Uninterrupted Ac Electrical Power sys-A.Caused by Setpoint Drift of Adjustable Frequency Potentiometer.Setpoint Readjusted

ML19309G361
Person / Time
Site:	Vermont Yankee
Issue date:	05/02/1980
From:	Murphy W VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19309G356	List: ML19309G355 ML19309G361
References
LER-80-014-03L, LER-80-14-3L, NUDOCS 8005060216
Download: ML19309G361 (2)

Text

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REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h o 2 l Durine routine reactor startup. Operations personnel observed frequency drifting i 10 l 31 1 on the UPS-A System. In order to allow further investigation of the frequency l 10141 l drift, it was determined that the UPS System had to be removed from service. l lO Isl l There were no adverse consequences to the public health or safety as a result of l l O 10 I [_t;his event. I 10171 1 I 10181 l i SYSTEM CAUSE CAUSE COMP. VALVE CODE CODE SUBCODE COMPONENT CODE SU8 CODE sUBCODE 10191 I E l D l h l X_jh [Z_j h l Z l Zl Z l Z l Z l Z lh l Z lh 20[ Zj h i 8 9 10 11 12 13 18 19

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33 35 36 3/ 40 42 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h l i 101 l The cause of this occurrence was a set point drift of the adjustable frequency l l1 lI ll_ Dotentiometer. The corrective action taken was to readjust the potentiometer l i 2 I for proper frequency output of the UPS-A System. No further corrective action l i a l is envisioned at this time. l 1 4 l l 1 8 9 80 STA 3  % POWER OTHER STATUS is O RY DISCOVERY DESCRIPTION I1 15 I (_cj h l 0 l 1 l 0 l @ l NA I lB lhl Operator Observation l A TlVITY C TENT RELEASED OF HELE ASE AMOUNT OF ACTIVITY LOCATION OF RELEASE I I NA l Ii Ic 8I Lz)

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VTVYS1 05000271 LER 80-14/3L EVENT DESCRIPTION AND PROBABLE CONSEGUENCES During reutine reactor startup, Operations personnel observed fre-quency drifting on the UPS-A System. In order to allow further investi-gation of the frequency drift, it was determined that the UPS System had to be removed from service. This condition is contrary to the require-ments of Tech. Spec. Section 3.10.B.4 and alternate testing in accordance with Technical Specifications Section 4.5.A.4 was initiated. During this event, the redundant "B" UPS System, both Core Spray Subsystems, the Con-tainment Cooling Subsystems, the "B" LPCI Subsystem and both diesel gen-erators were operable. Based on the above equipment availability and the short time elapsed, approximately 30 minutes before UPS-A was declared operable, it is concluded that there were no adverse consequences to the public health or safety as a result of this event. No similar occurrences were reported.

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