ML19289E713

LER 79-012/03L-0 on 790419:oxygen Level in Suppression Chamber Atmosphere Was Greater than 5%.Caused by Sensitivity of Sampling Sys & Position of Sample Flow Control Valve. Oxygen Analyzer Recalibr;Level Now Below 5%

ML19289E713
Person / Time
Site:	Oyster Creek
Issue date:	05/17/1979
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19289E709	List: ML19289E708 ML19289E713
References
LER-79-012-03L, LER-79-12-3L, NUDOCS 7905290017
Download: ML19289E713 (3)

Text

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7 8 60 61 DOCKET NUMBER 6e O EVENT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h O 2 l On AorIl 19_ 1979. In violatInn of T E_ t _ C; _ A _ A _ the nvvnen Inval in the l 0 3 i suppression chamber (torus) atmosphere was greater than 5%. Prior to a 1 0 4 I surveillance calibration test of the torus oxygen analyzer, the torus 1 0 s I oxygen concentration was recorded as 4%. After the ant l yzer calibra- l 0 6 l tion Was completed, the torus oxyaen level measured as hiah as 5.75%.

O 7 1 The oxygen concentration was reduced to below 5% by inerting with nitro- l 0 a gen in less than two hours after the abnormality was discovered. I 80 7 8 9 SYSTEM CAUSE CAUSE C OY P. VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE 7

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47 CAUSE OESCRIPTION AND CORRECTIVE ACTIONS h i O l The cause of this incident is attributed to a combination of the sensi- l 11 liI I tivity of the samolina system and the oosition of the samol e flow con- 1 i 2 l trol valve. The analyzer was recalibrated af ter torus inerting was com- l ti]3l l pleted and the oxygen level was verified to be below 5%. The torus ox- l gl ygen concentration will normally be kept below 3% in the future. I 7 8 9 80 ST S "4 POWER OTHER STATUS DIS O RY DISCOVERY DESCRIPTION 1 5 d @ l0l9 9l@l NA l l L l@l Surveillance Calibration ACTIVITY CONTENT RELEASED OF RELE ASE AMOUNT OF ACTIVITY LOCATION OF RELEASE NA l l NA l l7t_[6_] 8 9

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NAME OF PREPARER PHONE 201-455-8478 {

Jersey Central Power & Light Company j{y e(f ( l-

,wy p[1i . Madison Avenue at Punch Bowl Road Morristown, New Jersey 07960 (201)455-8200 OYSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Licensee Event Report Reportable Occurrence No. 50-219/79-12/3L-0 Report Date May 17, 1979 Occurrence Date April 19, 1979 Identification of Occurrence Violation of the Techn! al Specifications, paragraph 3.5.A.6, when the primary containment atmosphere oxygen level was greater than 5%. This event is con-sidered to be a reportable occurrence as defined in the Technical Specifica-tions, paragraph 6.9 2.b.2.

Condi tions Prior to Occurrence The plant was being operated at steady state power.

Power: Electrical, 670 MWe Reactor,1912.1 Mwt Flow: Feedwater, 7.146 x 10 0 lb/hr Recirculation, 14.9 x 10 4gpm Description of Occurrence On Thursday, April 19, 1979, at approximately 1540 hours0.0178 days <br />0.428 hours <br />0.00255 weeks <br />5.8597e-4 months <br />, the Instrument De-partment completed a surveillance calibration test on both the drywell and torus oxygen analyzer. Prior to the calibration, the torus oxygen concentra-tion was recorded at approximately 4.0%. The torus oxygen concentration was measured at 4.9% during the calibration. Af ter placing the oxygen analyzer back in service, the oxygen concentration started to increase. At 1540 hours0.0178 days <br />0.428 hours <br />0.00255 weeks <br />5.8597e-4 months <br />, it was determined that the oxygen level in the torus was reading greater than 5% by volume. The Operations Department started preparations to inert the torus immediately and commenced inerting the torus at 1632 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.20976e-4 months <br /> at which time the oxygen concentration level was approximately 5.75% by volume. The torus oxygen concentration was reading below 5% by volume at 1647 hours0.0191 days <br />0.458 hours <br />0.00272 weeks <br />6.266835e-4 months <br /> as a result of inerting operations.

2025 153 Jersey Central Power & Lght Company is a Member of the Genera! Puttc Utsties System

Reportable Occurrence No. 50-219/79-12/3L-0 Page 2 May 17, 1979 Apparent Cause of Occurrence The cause of the occurrence was a combination of the sensitivity of the sampling system and the position of the flow control valve.

Analysis of Occurrence The primary containment inerting system introduces a nitrogen atmosphere into the primary containment. The system is capable of reducing and maintaining the oxygen content of the atmosphere to a level not to exceed 5% by volume. The control system is designed to maintain an Inert atmosphere in the primary con-tai nment to preclude energy releases from a possible hydrogen-oxygen reaction following a postulated loss-of-coolant accident which could jeopardize the in-tegrity of the primary containment.

After surveillance testing, the plant Operations personnel recognized the dis-crepancy in the oxygen level, investigated, and corrected the situation in a timely manner.

Corrective Action Another calibration on the torus oxygen analyzer was performed af ter inerting which verified that the oxygen concentration was below 5% by volume. The flow control valve was adjusted to maintain correct flow to the torus oxygen analyzer.

In order to account for the uncertainties caused by the sensitivity of the sam-pling system and the flow control valve, the torus oxygen concentration will be kept less than 3 0%.

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