05000219/LER-1980-033-03, /03L-0:on 800806,24-h After Reactor Mode Switch Was Placed in Run,Torus Oxygen Concentration Found in Excess of 5%.Caused by Torus Oxygen Analyzer Out of Calibr & Reduced Flow Capability of Nitrogen Purge Sys

/03L-0:on 800806,24-h After Reactor Mode Switch Was Placed in Run,Torus Oxygen Concentration Found in Excess of 5%.Caused by Torus Oxygen Analyzer Out of Calibr & Reduced Flow Capability of Nitrogen Purge Sys

ML19337A258
Person / Time
Site:	Oyster Creek
Issue date:	08/28/1980
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19337A238	List: 05000219/LER-1980-033, Forwards LER 80-033/03L-0 05000219/LER-1980-033-03, /03L-0:on 800806,24-h After Reactor Mode Switch Was Placed in Run,Torus Oxygen Concentration Found in Excess of 5%.Caused by Torus Oxygen Analyzer Out of Calibr & Reduced Flow Capability of Nitrogen Purge Sys
References
LER-80-033-03L, LER-80-33-3L, NUDOCS 8009090381
Download: ML19337A258 (4)

LER-1980-033, /03L-0:on 800806,24-h After Reactor Mode Switch Was Placed in Run,Torus Oxygen Concentration Found in Excess of 5%.Caused by Torus Oxygen Analyzer Out of Calibr & Reduced Flow Capability of Nitrogen Purge Sys

Event date:
Report date:
2191980033R03 - NRC Website

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8 80 81 DOCICET NuuSER 88 89 EVENT DATE 74 75 REPORT QATE 80 EVENT DESCRIPTION AND PRO 8A8tE CONSEQUENCES h 7

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FITI l On Wednesday, August 6,1980, at approximately 0939 hours0.0109 days <br />0.261 hours <br />0.00155 weeks <br />3.572895e-4 months <br /> (24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> l

ITTTl I after the reactor mode switch was placed in RUN), the torus oxygen con-1: -

I o i A l 1 centration was found to be in excess of 5% in violation of T.S. 3.5. A.6.

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io #s: 1 Containment inerting at reduced capability was in progress at the time.

I lo is i l A reactor shutdown was commenced while the inerting orocess continued.

l l o l 71 l At 1003 the shutdown was terminater' when the torus oxygen concentration l

i ois ; l was reduced,-and remained below, 5%.

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33 34 35 38 37 40 el 42 43 44 47 CAusE DESCRIPTICN AND CORRECTIVE ACTIONS h li l a l l The cause of this occurrence is attributed to the torus oxycen analvrer l

L' L2_J l being out of calibration and to the reduced flow caeabilitv of the l

I: 121 i nitrogen purge system.

A reactor shutdown was commenced.

The nitrocen I

Ld.3J Lourge system was made to operate at a creater flew rate. and after about I

y 1 1/2 hour, the torus oxygen was less than St.

The shutdown was terminated.

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t i s so Ross 201-455-878h PHONE:

NAME OF PREPARER

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I' Jersey Central Power & Ught Company 2)

Madison Avenue at Punch Bowl Road Monistown, New Jersey 07960 (201)455-8200 OYSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 2'

Licensee Event Report Reportable Occurrence No. 50-219/80-33/3L Report Date August 28, 1980 Occurrence Date r

August 6, 1980 Identification of Occurrence The primary containment atmosphere was not reduced to less than 5.0% oxygen concentration within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after the reactor mode selector switch was placed in the RUN mode as required by Technical Specifications paragraph 3.5. A.6.

This event is considered to be a reportable occurrence as defined in the Tech-nical Speci fications, paragraph 6.9.2.b(2).

Conditions Prior to Occurrence The plant was operating at steady state power.

Plant parameters at the time of occurrence were:

Power:

Reactor, 1544 Wt Electrical, 463 We Flow:

Recirculation 11.6 x 104 gpm Feedwater 5.35 x 10' lb/hr Stack Gas Activity:

1.6 x 103 pCi/sec Descriotion of Occurrence On Wednesday, August 6,1980, at approximately 0939 hours0.0109 days <br />0.261 hours <br />0.00155 weeks <br />3.572895e-4 months <br /> (24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> af ter plac-

~ j ing the reactor mode switch in RUN) the torus oxygen concentration was greater than 5.0%.

Containmen: Inerting was in progress at the time and had been since about 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br /> on August 5, 1980.

The Nitrogen Purge System, however, was discovered to be operating in a reduced status due to a faulty high temperature cutout switch in the nitrogen purge vaporizer.

This rendered one set of the vaporizer beaters inoperable making it

_ Jersey Cen:ral P:wer & Uger Comcany :s a Verncer cf :re General Pucic Utttes Sys:em l-

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- Reporttblo-Occurrsnca No. 50-219/80-33/3L Pcga 2 t1 August 28,.1980-i necessary to reduce the nitrogen purge rate.

Two other sets of heaters were also operating' in a reduced status. At 0050 on August 6, the torus oxygen con-

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centration indicated 5.0% at which' time a nitrogen purge of the drywell was s ta'rted. At about 0830 on August 6, a calibration of the drywell and torus oxy-4 gen analyzers was performed. After the calibration, -the indicated oxygen con-centrations in the drywell and torus were 3.6% and 7.3%, respectively. The purge was shifted back -to the torus but the oxygen concentration could not be reduced to less than 5.0% by 0939 hours0.0109 days <br />0.261 hours <br />0.00155 weeks <br />3.572895e-4 months <br />.

The indicated torus oxygen concentra-

.tlon at 0939 was about 6.2%.

At that time a reactor shutdown was commenced while the inerting process continued. At 1003 hours0.0116 days <br />0.279 hours <br />0.00166 weeks <br />3.816415e-4 months <br /> the shutdown was termi-nated when the torus oxygen concentration was reduced to, and remained below, 5.0%.

Apparent Cause of Occurrence The cause of the occurrence was attributed to the indicated torus oxygen concen-tration increasing following instrument calibration compounded by the nitrogen purge system operating in a reduced status.

Another contributing factor in the event was that the drywell oxygen analyzer was operating without a sample pump. This requires the operators to estimate when the drywell oxygen concen-tration is less than 5%. The drywell must then be pressurized in order to obtain sample flow to the analyzer.

in this Instance the drywell indicated 3.6% oxygen after calibration.

Had the operators had continuous indication of drywell oxygen they could have shifted the nitrogen purge back to the torus early enough.to reduce the torus oxygen to less than 5.0% within the required time.

Analysis of Occurrence The containnent atmosphere control system is designed to maintain an inert atmos-phere within the primary containment to preclude energy releases from a possible hydrogen-oxygen reaction following a postulated loss of coolant accident which could jeopardize the Integrity of the containment.

Conservative estimates of the hydrogen produced following the postulated loss of coolant accident with the operation of either core. spray system show that the hydrogen produced from the metal-water reaction would result in a hydrogen concentration of 0.4% in the primary containment. This concentration is significantly below the concen-tration at which hydrogen can be ignited in air.

However, inerting of the pri-mary containment was included in the proposed design and operation to preclude the possibility of an energy release within the primary containment from a hydrogen-oxygen reaction under more severe conditions than could be foreseen.

in iaddition, considering the drywell oxygen concentration was reduced to less than 5.0% ar.d the torus oxygen concentration was above 5% (6.2%) for only a short length of time, the safety significance of this event is considered minimal.

Corrective Action

A reactor shutdown was commenced'while N2 purging operations continued.

The high temperature cutout switch in the nitrogen purge vaporizer was jumpered out allowing the system to operate at a greater flow rate.

At 1003 hours0.0116 days <br />0.279 hours <br />0.00166 weeks <br />3.816415e-4 months <br />, the torus 02 concentration was reduced to less than 5% and the shutdown was terminated.

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. Reportable.0ccurrence No. 50-219/80-33/3L Page i,

August 28, 1980-J!

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Failure Data.

1 1ki CEXI Electric Vaporizer I'

' Cryogenic Experts,- Inc..

Serial #100E-36

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