ML20041A595

Updated LER 81-049/04T-0:on 811109,main Vent & Waste Gas Discharge Header Radiation Monitors Alarmed.Probably Caused by Gas Leakage Past VCT Supply Check Valve W/Vct Relief Valve Lifting at Below Setpoint Pressure

ML20041A595
Person / Time
Site:	Calvert Cliffs
Issue date:	02/09/1982
From:	Paris G BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20041A593	List: ML20041A592 ML20041A595
References
LER-81-049-04T, LER-81-49-4T, NUDOCS 8202220321
Download: ML20041A595 (2)

Text

NRC FOZM 366 U. S. NUCLE AR CEGULATOR Y CO*WISSION

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LICENSEE EVENT REPORT OU ORT DATE: 2-9'82 ComRotstoCleI l I I i i Ig i,tE ASE ,RiNT oR Tv,E Att REauinEo iNroRuATioNi l0 l 1B l9 l Ml Dl 7

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EVENT DESCRIPTloN AND PROBABLE CONSEQUENCES h 10121 l While in Mode 3 at 0914. the main vent and unste enn dinchnrco honanr I o 3 l radiation monitors alarmed denoting a radioactive release. Operators l 1

gol4l l immediately vented the volume control tank to the waste gas system. I inIsi l .t 0919, the radiation monitor alarms elected, terminating the event. I j o lc l l Sampling and calculations revealed that the instantaneous release rate l -

lol7ll was exceeded (E.T.S. 2.3.B.1). The health and safety of the public J loisi 1 was not affected. Similar events: none. l 7 g 9 80 SYSTEV CAUSE CAUSE C OY P. VALVE CODE CODE SUBCODE COYPONENT CODE SUBCODE SUBCODE l0jlj 1 B l Rl Blh dh Wh l V! Al T.] VI El Xlh l Xlh 9 10 11 12 13 18 13 h

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42 h W h lC l 7I ll 0] h 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS 21 lilo l l Event probably caused by leakage of gas past VCT supply check valve j i i l and VCT relief valve lifting at pressures below setpoint value. I j,,,,j Immediate action was to administratively limit VCT pressure tc l l,l3l l 50 PSIG maximum. Repairs on check valve and relief valve to be j

[ij4j l performed during next refueling outage. l 7 8 9 80 ST S  % POWE R OTHER ST ATUS E IS O R DISCO \t EHY DESCHIPTION l1 l5l [_D_j h l 0 l 0 l 0 l h l NA l lAl@l Operator Observation l A TIVITY CONTENT HELEASED OF RELE ASE AYOUNT OF ACTIVITY LOCAT'ON OF RELE ASE 7

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• s LER NO.' . 81-49/4T DOCKET NO. 50-318 LICENSE NO. DPR-69 EVENT DATE 11-09-81 REPORT DATE 02-09-82 ATTACHMENT EVENT DESCRIPTION AND PROBABLE CONSEQUENC55 (CONT'D)

On November 9,1981, at 0902 with Unit No. 2 in Mode 3, the Control Room Operator (CRO) commenced blended make-up to the Volume Control Tank (VCT) in response to a VCT low level alarm; Make-up was terminated at'0907 af ter the VCT. level alarm cleared. {At that point, VCT pressure was approximately 60 PSIG. At 0914, the main vent and waste gas discharge header radiation monitors alarmed. The CRO immediately vented the VCT to the waste gas system, observing VCT pressure at 63-64 PSIG. VCT s

pressure decreased to the low alat m setpoint at 0917, at which point the CRO secured the VCT vent to the waste gas system. At 0919, the radiation monitoring system alarms cleared, terminating instantaneous release rate thewasevent.7.02E5 Sampling M /seqfor the duration of the event. Thisand subse corresponds to 1.82 times the maximum instantaneous release rate specified in E.T.S.

2.3.B.I. The total release resulting from the event was 38.6 Curies,0.043% of the allowable quarterly release limit. This release resulted in a total dose at the site boundary of 0.llmR. Similar event: None. '

CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (CONT'D1

' Event probably caused by leakage of gas past VCT N7 /H2supply check valve (2-CVC-195) and the VCT relief valve (2-CVC-105-RV) lif ting at pYessure's approximately 6 PSI lower than the design setpoint of 7012 PSIG, thereby venting the VCT to the main vent.

Immediate action was to administratively limit VCT pressure to 50 PSIG maximum.

Subsequent action will be to reestablish the relief valve setpoint of 70 22 PSIG and to perform the necessary repsirs on the check vuve. 'This work is scheduled for the next refueling outage. .  :

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