ML20064G176

/03X-1 on 780728:particulate Filter & Charcoal Filter Were Clogged.Caused by Driving Mechanism of RM-RMS-159 Filter Being Jammed

ML20064G176
Person / Time
Site:	North Anna
Issue date:	12/01/1978
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20064G174	List: ML20064G171 ML20064G176
References
LER-78-063-03X, LER-78-63-3X, NUDOCS 7812070195
Download: ML20064G176 (2)

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J3 34 35 37 40 di 43 44 CAUSE DESCHIPTION AND CORRECTIVE ACTIONS li l o l l The filter for RM-RMS-159, containment particulate monitor became cloaced because the I l i li l I driving mechanism for the continuous filter became .iammed. Charcoal filtor fnr I i1 i2i lRM-RMS-160, gas radiation monitor, was also cloqqed. I t

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Attachment:

Paga 1 of 1 Docket No. 50-338 .

Report No. LER/R0 78-063/03L-1 Event Description On 7-28-78, while investigating a simultaneous Hi and to flow alarm in the sample line for containment particulate moaltor, RM-RMS-159, and cdntainment gas radiation monitor, RM-RMS-160, the particulate filter and charcoal filter were found to be clogged. When the particulate filter (a continuous filter) was advanced and the charcoal filter replaced, the indicated radiation levels ,

increased setting off the hi-hi radiation alarms. Therefore, both chan~nels were indicating a radiation level less than actual. The containment gaseous ,

activity and containment particulate activity monitors are required to be opera-ble by T.S. 3.3.3.1 and T.S. 3.4.6.1. This is reportable by 1.S. 6.9.1.9.b.

Probable Consequences / Redundant Systems

( Entry into the containment is restricted at this time due to high neutron radiation levels; therefore, the low indication of radioactivity in the con-tainment would not affect personnel exposure. The process vent particulate monitor (RM-GW-101) and process vent gas monitor (RM-GW-102) monitored any releases from containment via the containment vacuum pumps. Event had no effect on health or safety of public.

Cause Description The filter for RM-RMS-159 became clogged because the driving mechanism for the contiquous filter became jammed. The charcoal filter for RM-RMS-160 was also clogged. Present procedure is to change the particulate filter on RM-RMS-159 whenever the filter runs out. The charcoal filter is normally '

changed only when there is low flow through the sample line. No explanation for simultaneous Hi and to flow alarms in the sample line is apparent.

Immediate Corrective Action ,

The particulate filter for RM-RMS-159 was unjammed and advanced and the ,

charcoal filter for RM-RMS-160 was replaced resulting in hi-hi radiation "

alarm. The setpoints for the alarms were reset to health physics recommenda- i tions.

i Future Corrective Action RM-RMS-159 will be checked for alarm conditions at the frequency required by the applicable periodic test. The appropriate periodic test (1-PT-37) will be changed accordingly.

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