ML19347C797
| ML19347C797 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 01/28/1974 |
| From: | JERSEY CENTRAL POWER & LIGHT CO. |
| To: | |
| References | |
| AO-50-219-74-6, NUDOCS 8103040554 | |
| Download: ML19347C797 (2) | |
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sg P.W c F;h. 07 OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Abnormal Occurrence Report No. 50-219/74/6 i
i h,EltGt0[.y Report Date:
.'A January 28, 1974
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'd) YTh January 22, 1974 Identification of-Occurrence:
Twenty-four hours after placing the mode selector switch into RUN, the
. torus atmosphere contained 6.2% 0, which is above the limit of 5.0*6 0-2 2
This event is considered to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15B.
Conditions Prior to Occurrence:
. Routine plant startup was in progress.
The major plant parameters at the time of the event were as fo11owsM1 ; ;5??x j
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X; Reactor Power
- 1075 MWt =340 MWe Recirculation Flow
- 7.4 x 10 gpm
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j;g 39 374 s
j Feedwater Flow
- 3.8 x 106 lb/hr LT
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' Feedwater Temperature - 275'F
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Reactor Pressure
- 1020 psig Q,
- 3 j3 Reactor Water Level
- 78" Yarway i-N
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Description of Occurrence:
At 2030 on January 21, 1974, the primary containment inerting process I
was initiated by first performing a calibration on the torus /drywell 02 analyzer, a' per the operating procedure. The torus atmosphere was then.
inerted with nitrogen to 4.8% 02 as indicated in the drywell/ torus oxygen recorder and drywell inerting was then commenced. During this process, j
. a "zero check" on the analyzer showed that the instrument "zero" was low.
Correcting this condition brought the indicated 02 level in the torus to l-6.2%.
Since drywell inerting was already in progress, it was decided to i.
reinert the torus after drywell inerting was complete. Due to a misunder-standing of the procedure on the part of the shift foreman, an attempt was made to inert the drywell to less than 1% 02 content.
Prior to attain-(ng this condition, the plant nitrogen supply reached a level where further consumption in the inerting process would have exhausted the operational
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supply needed for the nitrogen / air system in the drywell.
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Abnormal Occurrence Report No. 50-219[74/6 Page 2 An orderly plant shutdown at a 30 MWe rate was started at 1000 on January 22, 1974, 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after going into the RUN mode. Power was reduced to 292 MWe at which time a temporary Technical Specification change was obtained which allowed operation at 50% reactor power with greater than 5% 02 concentration in the primary containment until 1230 on January 24, 1974.
Apparent Cause of Occurrence:
A misunderstanding of the operating proceaure was the main cause of this event. The shift foreman in charge of this operation misjudged the capacity of the plant nitrogen system.
In addition, the foreman was informed that a nitrogen truck was enroute and would arrive Tuesday. morning with the additional nitrogen needed to complete the inerting process. Unfortunately, due to internal problems, the nitrogen vendor was unabic to meet the required delivery time.
Analysis of Occurrence:
The significance of this event lies in operating the reactor at power with an inadequately inerted containment which, under design bases LOCA conditions, would have created a condition whereby the probability of ex-periencing an explosive concentration of oxygen and hydrogen in the con-tainment would have been increased.
Corrective Action:
The nitrogen truck arrived at the site and inerting of the torus to less than 5% 02 concentration was completed by 2:40 p.m. on January 22, 1974.
The nitrogen purging procedure will be revised to eliminate the chance for misinterpretation by adding a caution statement informing the operator that the nitrogen system with a full nitrogen tank is only capable of reducing the 02 concentration to approximately 4.5%.
In addition, a Technical Specification change request will be initiated to allow operation when the primary containment is not inerted to less than the 5% 02 limit.
Failure Data:
Not Applicable.
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