ML20084G848

Ro:On 720122,while Verifying Alarm Actuations,Loss of 125-volt Dc Voltage on Bus a Occurred.Loss of Voltage Caused Feedwater & Recirculation Pumps to Trip.Appropriate Switches Will Be Caution Tagged

ML20084G848
Person / Time
Site:	Oyster Creek
Issue date:	02/22/1972
From:	Finfrock I JERSEY CENTRAL POWER & LIGHT CO.
To:	Morris P US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084G835	List: ML20084G844 ML20084G848
References
NUDOCS 8304270023
Download: ML20084G848 (2)

Text

- ,

O i

y .

O .

n. r .

Jersey Central Power & Light Company M ADISoN AVENUE AT PUNCH BOWL Ro AD e MoRRISToWN, N.J. 07960 e 539 6118 February 22, 1972 t- O j j g ,

0) t ;/

I ( {w- 3i Dr. Peter A. Morris, Director b '"

Division of Reactor Licensing 2 EEB 25872*

i United States Atomic Energy Commission @"- g pg vra Jf Washington D. C. 20545 WW

/ ru.ht r s b./

m scs . .

Subject:

Docket 50-219 Ih h Oyster Creek Station j Loss of 125V DC Bus "A" -- January 22, 1972 l On January 22, 1972, while verifying alarm actuations, the 125V DC control feed to bl60V "A" bus was changed from 125V DC Bus "A" to 125V DC Bus "B" and immediately returned to "A". The loss of I DC voltage on h160V "A" control bus caused the holding voltage to be lost on the polarizing coils for the Reactor Recirculation Pump M.G.

ret field breakers which caused a trip of Recirculation Pumps "A",

i "C", and "E". In addition, the "A" Feedvater Pump was lost when auxiliary relay PSX, which monitors feed pump suction pressure and pump oil pressure, lost D.C. power which put it in a tripped condi-tion. The immediate reclosing of the D.C. feed back to "A" bus caused the trip coil to be energized before the PSX contacts returned to normal. The same condition was experienced on the t Cleanup System from auxiliary relay TSX vhich normally monitors the Cleanup System Main Recirculation Pump discharge temperature.

The "A" Feedvater Pump was immediately restarted. The Recirculation Pumps were restarted one at a time and the Cleanup

, System was returned to service after the Recirculation System was '

normal.

i h All plant parameters responded normally with the following

-jig rt results:

f Electrical load dropped from 642 MWe to a lov of 316 MWe i )) andthenleveledoffat336MWe;recireglationflow

/* dropped from 1.60 x 105 gpm to 4.8 x 10 gpm; core power dropped initially to 20% and immediately returned to 50%;

vessel water level dropped from 13' 9" above the active (h 'O

?"*R88dMgh yr PDR 1,

, .- f n 949 copy SENTREGION_ #

t m

• ~

. , t

-\  ! '

(u

, , (/

Dr. Peter A. Morris Page II February 22, 1972 fuel to 12' 9" above the active fuel; the "B" and "C" Feedvater Pumps were in a run-out condition and level increased to approximately 14' 9" at which point the run out reset and level returned to 13' 9" above the fuel; and reactor pressure dropped from 1018 psig to 960 psig.

In view of this incident, all appropriate switches will be CAUTION tagged and appropriate precautions will be added to all plant operating procedures. In addition, electrical maintenance personnel have been instructed to review station procedures prior to deenergizing any DC circuits and an investigation will be made of the possibility of making circuit modifications that would eliminate future probicms of this nature.

We are enclosing twenty-five copies of this report.

Very truly yours,

$(b)l 7! 2-Ivan R. Finfrock J.

Manager, NucIe'ar, Generating Stations IRF/pk Enclosures cc: Mr. J. P. O'Reilly, Director Division of Co:apliance, Region I

~