ML20083Q021

Ao:On 730212,low Sample Flow Identified in Stack Monitor Sys.Caused by Moisture Freezing in Sample Line at 262-ft Elevation.Line Thawed Out

ML20083Q021
Person / Time
Site:	Oyster Creek
Issue date:	02/27/1973
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8302220516
Download: ML20083Q021 (2)

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A M ADisoN AVENUE AT PUNCH BOWL Ro AD e MoRRisToWN. N.J. 07960 e 539 6111 February 27, 1973 .

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Mr. A. Giambusso . 3 Deputy Director for Reactor Projects $ g- 7 Directorate of Licensing -

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United States Atomic Energy Commission U8 digE j 88Y '

Washington, D. C. 20545 Regulatory

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Dear Mr. Giambusso:

4. Nail Sectica

Subject:

Oyster Creek Station Docket No. 50-219 Failure of Stack Gas Monitoring System ,

This event is considered to be an abnormal occurrence, as defined in the Technical Specifications, Paragraph 1.15.B. Notification of this event, as required by the Technical Specifications, Paragraph 6.6.B, was made to the AEC Region I, Directorate of Regulatory Operations, on February 12, 1973.

At the beginning of the day shitt on February 12, it was recognized that low sample flow existed in the stack monitor system.

The filters were inspected and found not to be the cause of the low flow. Warm air was blown back through the sample line but no improve-ment in sample flow was realized. At 11:10 a.m., an orderly shut down-of the plant was initiated when it was determined the stack gas moni-toring system was no longer functioning properly. Increased surveillance of the continuous off-gas monitor was used to infer stack release rates during the period.

Upon investigation, the cause of the monitor flow problem was determined to be moisture freezing in the sample line at the 262 foot elevation where the line runs external to the stack. The line was thawed out and heat traced to prevent future freezing. At 3:40 p.m.,

sample flow was reestablished and the stack monitor was determined to -

be functioning properly. The plant shutdown in progress was then terminated.

Upon further investigation into thi~s occurrence by the Plant Operations Review Committee, it was recognized that on February 11 the stack gas filter had been changed due to noting a low sampic flow rate.

While the filter was being changed, the sampic line was blown out.with air. The monitor ficw returned to normal; however, later that day the flow rate again decreased and technicians were called in to check out the monitoring system. At this time, for a period of approximately three hours, the gaseous stack releases were not being properly monitored. '

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8302220516 730227 PDR ADOCK 05000219 S PDR . _ ,

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' February 27,.1973

The safety- significance attached to this- event is associnted with the. temporary. loss- of! gaseous effluent monitoring 'at the stack ~.~

liowever, during the-time the stack gas. sampling flow was reduced,'the

! off-gas monitor continued to provide continuous, related gaseous release

! monitoring. At no time did the activity indicated by these monitors increase above what they were reading prior to the stack gas sample flow problem. Samples of off gas analyzed-during this period showed l the stack release rate to be 8 x 104 uci/sec. The 1 131 concentration',

as determined by analysis of the charcoal cartridges in service during this period, showed an average release rate of .2 pei/sec.

l To prevent a recurrence of this event, the external portion-of the sample line has been insulated and heat tr' aced. In! addition, procedure 501, which covers the action required when receiving the stack gas sampic system low flow alarm, will be expanded to -clarify

( the operator action to be taken. This change will then be reviewed with all licensed personnel. '

.W Very truly yours, Gl*JCd f d&

Donald A. Ross i Manager, Nuclear Generating Stations pk Enclosures - (40) cc: Mr. J. P. O'Reilly, Director Directorate of Regulatory Operations, Region 1 5

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