ML20084H072
| ML20084H072 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 11/03/1969 |
| From: | Kelcec G JERSEY CENTRAL POWER & LIGHT CO. |
| To: | Morris D US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20084H075 | List: |
| References | |
| NUDOCS 8304270482 | |
| Download: ML20084H072 (4) | |
Text
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Jersey Centgl Power & Light Cg1pany/p' ff'g j g.
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New Jersey Power'& Light Company fg8 At MADISON AVENUE AT PUNCH UOWL.
OAD ORRISTOWN. N. J. e Jefferson 9-0111
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Dr. Peter A. Morric Director Division of Reactor Licencing United States Atomic Ener y Conniccion Wachington, D. C.
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Dear Dr. Morric:
Re: Report of Abnormal Occurrence Oycter Cre nuclear Generating Station - Unit No. 1 September 9, 1969
- SUBJECT, TurbinbInitialPrecoureRegulator(operatin6orelectricpreccureregulator) malfunction cauced an unplanned reactor trip at the Oycter Creek Huclear Generating Statien of the Jercey Central Power & Light Company on September 9, 1969 Reference AEC Operating Licence DPR-16, Technical Specification, thereof,Section I - Definitionc, Sub-Paragraph 1.150, and Section 6 3
" Actions to be Taken in the Event of an Abnormal Occurrence in Plant Operat$on."
SITUNfIO?i The start-up testing of the Oycter Creek reactor vac in progrecc with the reactor in the " Start-Up Mode" at a power level of approximately 40 MWT and 9'(0 poig. The reactor van steaming with cteam being cupplied to the steam jet air ejectors, the turbine gland coal cycten and being dumped to the condencern throuch the bypaco valvec. The electric proccure regulator vac controlling the reactor preocure; the back up or mechanical precoure regulator van cet at approximately 1020 poig and the Qne load limit vac cet at zero
'(preventing any control valve opening). The control room operator van in the procccc of adjusting the electric precoure regulator cet point when the regulator cignal vent full ceale and caused the bypacc valves to go full open.
The reactor began to depreccurize. The operator then raised the cet point to its maximum cetting, but the regulator ctill called for full oper. The reactor ceram occurred at 2:16 p.m. on September 9,-1969 The next operator action was the clocing of t,he incide main steam icolation valvec which cauced an increase in reactor preccure and a decrease in reactor level. Approximately
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104 ceconde after the ceram, the reactor low-low level trip occurred causing g
[G8b reactor icolation, containment icolation, core spray and contairrnent spray preliminary actuation, emercency dieselc to idle, recirculation pumps to trip, standby gac treatment cycten operation and icolation condencer operation.
Reactor level ber;an to increace at approximate 3y 105 to 2 ceggdge go 8304270402 691103*
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0,,vembe,3, 1gc, Dr. Peter A. Morric rese 2 US AEC l
SITUATION (continued) feedvater flow increase and at approximately 320 seconda due to isolation condencer valvec opening. When water level returned to 12' 2" above the core (at approximately 180 ceconda), the operator tripped the core spray pumps while reactor preocure vac still around 600 poig.
CAUSE IJTD RESULTS Examination of station recordo dicclosed the fact that due to depreocurization, the ind$ cated recircuhtien loop flove decreaced to and pasced through zero
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vhien brought the flow biased trip line down to the operating power level and cauced the reactor to trip. The otrcng downscale output of the recirculation flow meacuring circulta vac apparent 3y due to depreocurization effects at the flow nozzlec and to the fact that the instrument calibration at ambient condi-tionc reculted in a negative flow input at operating temperatures.
The depreccurization of the reactor veccal caused by the open bypaca valvec vac terminated with the el.ocure of the incide main stream icolation valves approximately ninety reconds after the bypaca valvec had been opened. After the reactor had been chut down, the electric precoure regulator vac ctill j
calling for full bypacc valve opening. While checking the circuitry, the signal' cleared and it vac not poccible to dotermine the exact cauce of the failure.
CORRECTIVE ACTION TAKEN The amplifier and its output circuitry that cupplied the cignal to open the bypass valvec vac removed from the electric regu htor and returned to the manufacturer's chop for tecting. As of thic date, no official report of the tect results has been received. The defective amplifier vac replaced with identical equipment and has operated satisfactorily ever since. In addition, a power cutoff cvitch vac installed on the main control panel at the location of the electric regulator controls co that if a similar cituation chould M
develop, the operator can cut off all power to the regulator and cauce the f
valvec to move in the cloce direction. With the electric regulator out of service in thic : anner, the mechanical or backup regulator will take over the y reactor operating preocure control cyctem. Operating personnel have also been instructed to be prepared to adjuct feedvater flow due to the manual 7
operation of the feedvater control during thic light loud period and to run two condencate pumps to incure adequate feed pump suction at all times.
NUCLEAR SAFETY SIGUIFICANCE d
rrecoure regulator malfunctions have been analyzed and discuccion of the effect of opening the bypaca va'.ves is presented in the FDSAR, Section VII-8-1 as reviced 11/1/67 and Figure VII-8-b ac revised 12/19/67. As stated therein, blowdown from the hot c:andby condition leads to the moct rapid depreocurization rate.
In thc actual event,the depreocurination rate vac lecc than the previouc3y (actual data superimpoced on attached Figure VII-8-la) analyzed cace.
There vac a decrease in reactor water temperature of approximate 3y 125 F in 5 minutes l
for an average rate of 23 F per minute. All measured veccel metal temperaturec l
Dr. Peter A. Morrin Page 3 November 3, 1969 US AEC l
NUCIFAR SAFF/IT SIGIIFICAUCE (continued) indicated a rate of change of lecc than 100 F/ hour and all auxiliar/ cystems activated,by the low-low water level signal functioned properly.
CGICIU31Gi In conclusion, trc transient accociated with this event van less severe than the previously analyzed zent ac precented in the FDSAR and all nuclear safety l
oynteran functioned properly.
l Very truly yours, A
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peorgeKelcee Manager of Generating Stations GK/Je cc: Mr. R. W. Kirkman Director Division of Compliance Region I 9
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OYSTER CREEK NUCLEAR POWER PLAdT 3o dN11010'13 UNIT NO.1. F ACILITY DESCRIPTION Visd 3HOSS3Hd Ar $AFETY ANALYSIS REPORT Pressure Regulator Malfunction -
1600 MWt - Sheet 1 s
FIGURE Vll.8 la
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