ML20084G844

Ro:On 720203,loss of 125-volt Dc Voltage on Bus a Occurred Causing Feedwater & Recirculation Pumps to Trip.Operating Personnel Instructed to Review Procedures for Proper Operation of Dc Sys

ML20084G844
Person / Time
Site:	Oyster Creek
Issue date:	02/23/1972
From:	Finfrock I JERSEY CENTRAL POWER & LIGHT CO.
To:	Morris P US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084G835	List: ML20084G844 ML20084G848
References
NUDOCS 8304270019
Download: ML20084G844 (2)

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V' Jersey Central Pdweh) v I

Light Company M A'DISoN AVENUE AT PUNCH DoWL Ro AD e MoRHIST oWN, N.J. 07960 e 539-6111 February 23, 1972

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- w Dr. Peter A. Morris, Director , EO.

Division of Reactor Licensing

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'$O United States Atomic Energy Commission g ~

Washington D.C. 20545 ,

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Dear Dr. Morris:

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Subject:

Docket 50-219 Nw-Oyster Creek Station Loss of 125V DC Bus "A" -- February 3, 1972 On February 3,1972, electrical maintenance personnel requested the "A" Battery M.G. set be taken out of service and the load placed on the static charger. This involves opening a set of D.C. contactors from the Control Room and the opening of a breaker and the closing of another in the Battery Room.

Two cperators were aispatched to the Battery Room to perform the switching necessary to place the static charger in service and remove the M.G. set from service. The D.C. contactor on "A" M.G. set was opened from the Control Room, which placed the 125V DC "A" Bus load on the batteries. Then, instead of closing static charger tie to "A" Bus, the operator opened the "A" battery main breaker, which removed all feed from the 125V DC "A" Bus causing a loss of voltage. Prior to the start of the job, the Control Room Operator had reviewed the written procedure with the operators. As explained in my letter of February 22, 1972 that describes a similar incident that occurred on January 22, 1972, the loss of 125V DC voltage on the'"A" Bus caused the "A", "C", and "E" Recirculation Pumps to trip and the reener-gizing of the Bua caused the "A" Feedvater Pump and Cleanup i System to trip.

3 lb Following the incident, power was restored to 125V DC l _((

d* "'" Bus by closing the "A" Battery Main Breaker which energized t.c "A" Bus. The "A" Battery M.G. set was subsequently started "A" Feedwater Pump was immediately ljb b

4 s.d placed on the Bus.

restarted. Recirculation Pumps were restarted one at a time, and the Cleanup System was returned to service after the

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Recirculation System was normal.

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p V V Dr. Peter A. Morris Page II February 23, 1972 l

All plant parameters responded normally with the following results:

! Electrical load dropped from 640 MWe to 346 Ise and leveled I off at h00 !Ge;brecirculation flow dropped from 1.56 x 105 gpm to 5 7 x 10 gpm then leveled off at 6.5 x 10 hgpm; core power dropped initially to 2h% and immediately t

returned to 60". and leveled off at 65%; vessel water level I dropped from lh' 3" above the active fuel to 13' 6" above the active fuel; the "B" and "C" Feedwater Pumps were in l a run-out condition and level increased to 15' before dropping and leveling off at 13' 5" above the active fuel; and reactor pressure dropped from 1018 pai6 to l 965 psig.

The transient response was slightly different from the simil'ir trip which occurred on January 22, 1972 for the following l two reasons; 1) The "D" Recirculation Pump scoop tube was locked in the manual position due to oscillations, which are being investigated, causing the recirculation flow and electrical load to remain slightly higher; and 2) The Feedwater Pump and l Cleanup System trip did not occur ir"aediately but ware deleyed l approximately 1-1/2 minutes, which is the time it took the Shift l Foreman to reach the Battery Room and restore power to the 125V

! DC "A" Bus and, as previously discus.:cd, this caused the Feedwater Pump and Cleanup System trip.

All station operating personnel have been instructed to review the procedures for proper operation of the DC System.

We are enclosing twenty-five copics of this report.

Very truly yours, <

OY) i Ivan R. Finfro ):, Jr .

Manager, Nuclear Generating Stations IRF/pk Enclosures cc: Mr. J. P. O'Reilly, Director Division of Compliance, Region I

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