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Jersey Centra Power & Ligat Company g
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MADISON AVENUE AT PUNCH BOWL ROAD
- MORRIS g,,{", Public Utilities Corporation-Genotal January 28, 1974 N'
4 Mr. A. Giambusso Deputy Director for Reactor Projects
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United States Atomic Energy Commission 9-1 h'ashington, D. C. 20545 4e
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Dear Mr. Giambusso:
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Subject:
Oyster Creek Station i
normalbecur ce Report No. 50-219/74/6 Abnormal Occurrence Report in compliance with paragrap f
Technical Specifications.
of the Enclosed art. forty copies of this submittal.
4 Very truly yours, 2 M e
Donald A. Ross Manager, Nuclear Generat.ing Stations cs Enclosures Mr. J. P. O'Reilly, Director.
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Directorate of Regulatory Operations, Region I 9604180202 960213 PDR FOIA DEKOK95-258 PDR
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. OYSTER CREEK NUCLEAR GENERATING' STATION FORKED RIVER, NEW JERSEY 08731
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Abnormal 0ccurrence Report No. 50-219/74/6 Report Date:
January 28, 1974 at I
f Occurrence Date:
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% 0 -
2 This event is considered to be an abnormal occurrence as defined in the 2
Technical Specifications, paragraph 1.15B.
Conditions Prior to Occurrence:
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Routine pinnt startup was in prpgress.
The major ; plant parameters at the time of the event were as follows:
i Reactor Power
- 1075 MWt =340 MWe Recirculation Flow
- 7.4 x 10g'gpa Feedwater Flow
- 3.8 x 106 lb/hr Feedwater Temperature - 275'F Reactor Pressure
- 1020 psig
' Reactor Water Level.
- 78h Yarway; Description of Occurrence:
At 2030 on January 21, 1974, the primary containment inerting process l
was initiated by first performing a calibration on the torus /drywell 0
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. analyzer, as per the operating procedure. The torus atmosphere was then 2
j inerted with nitrpgen to 4.8% 02 as indicated in the drywell/ torus oxygen recorder and drywell inerting was then commenced.
During this process, 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 6.2%.
Since drywell inerting was already in progress, it was decided to 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% 0 2 content.
Prior to attain-
.ing this condition, the plant nitrogen supply reached a level where further consumption in the inerting process would have exhausted the operational supply needed for the ' nitrogen / air syst'em in the drywell, j
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Ab'norImal Occurrence Report No. 50-219/74/6
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i Page, 2
.An orderly plant-shutdown at a 30 We 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 I
reduced to 292 We at which time a temporary Technical Specification change was obtained which allowed operation at 50% reactor power with i
greater than 5% 02 concentration in the primary containment until 1230 on January 24, 1974.
Apparent Cause of Occurrence:
A misunderstanding of the operating procedure was the main cause of this i
The shift foreman in charge of this. operation misjudged the capacity event.
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 unable to meet the required delivery time.
Analysis of Occurrence:
De 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 ha.
been increased.
Corrective Action:
The nitrogen truck arrived at the site an'd inerting of the torus to less than 5% 02 concentration was completed by 2:40 p.m. on January 22, 1974.
he nitrogen purging procedare will, be revised to eliminate the chance 4
for misinterpretation by adding a caution statement informing the operator 3
that the nitrogen system with a full nitrogen tank is only capable of reducing the 02 concentration to approximately 4.5%.
L In addition, a Technical Specification change request will be initiated to i
allow operation when the primary containment is not inerted to less than the 5% 02 limit.
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Failure Data:
Not Applicable.
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