ML18136A316

LER 79-034/01T-0:on 791207,during Reanalysis,Discovered That When Radiation Alarm Setpoint Is Reached in Discharge Line of Air Ejectors of Units 1 & 2,trip Valves Divert Air to Containment.Caused by Valve Design Contrary to FSAR

ML18136A316
Person / Time
Site:	Surry
Issue date:	12/21/1979
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML18136A315	List: ML18136A314 ML18136A316
References
LER-79-034-01T, LER-79-34-1T, NUDOCS 7912270311
Download: ML18136A316 (2)

Text

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~ I During a recent analysis, a non-conservative feature was found that is contrary to an

~ FSAR commitment. When a radiation alam setpoint is reached in the discharge line of

[]JI] I the air ejectors of Units 1 & 2, trip valves divert air to the Containment. A CLS Hi

[o"Ts"l I signal will c~ose the Containment valve. If the CLS Hi signal is reset and a radiatiog

[QJ[) I alarm is still present, the valve will reopen without operator action. 'Tite CLS Hi signaO.

~ I is not reset until the Containment is sub-atmospheric. If a radiation alam is presentj,

((((I I a. release into the Containment will not affect the health & safety of the public.

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I Since the valve operates as designed, the discrepancy in valve operation was caused by

[III] ja design not in accordance with the FSAR. A detailed analysis has been initiated

[I]}] Ito provide for the conservative operation of TV-SV-102, 202 following the resetting of OJ)) I the CLS Ei signal.

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-- - e ATTACHMENT: Page 1 of 2 SURRY POWER STATION, UNIT 1 DOCKET NO: 50-280 REPORT NO: 79-034/0lT-O EVENT DATE: 12/7/79 TITLE OF EVENT: Discrepancy in Air Ejector Trip Valve Operation (TV-SV-102)

1. DESCRIPTION OF EVENT:

During a recent analysis, a non-conservative feature was found that is contrary to an FSAR commitment. The unreviewed safety question concerned a discrepancy in the operation of a Containment Isolation valve.

This event is reportable in accordance with Technical Specification 6.6.2.a.9.

2. PROBABLE CONSEQUENCES/STATUS OF REDUNDANT SYSTEMS:

The analysis revealed that when a radiation alarm setpoint is reached in_the discharge line of the air ejectors of Units 1 and 2, trip valves divert air to the containment. A CLS Hi signal will close the contain-ment valve. If the CLS Hi signal is reset and a radiation alarm is still pre*serit~ **the valve will *reopen without the operator taking manual action. However, the CLS Hi signal is not reset until the containment is sub-atmospheric. Therefore, if a_radiation alarm is present,~ release into containment will not affect the health and safety of the public.

3. CAUSE:

The non-conservative feature of the trip valve control system was caused by a design .that was not in accordance with the FSAR.

4. TI1MEDIATE CORRECTIVE ACTIONS:

_Upo:.i th.e discovery of the discrepancy in the trip valve operation, adminis-trative gui~elines were initiated to insure that prior to the resetting of the CLS Hi signal,*the air supply to TV-SV-102 would be isolated to prevent the valve- fro:i reopening without operator action. Appropriate action will be taken on TV-Sv-202 prior to unit startup.

5. SCEEDUI..ED COR..~CTIVE ACTION:

A detailed analysis has been initiated to provide for the conservative.

operarion of TV-SV-102, 202 following the resetting of the CLS Hi signal.

6. ACTION TAKEN TO PREVENT RECURRENCE:

Administrative action was taken to prevent the opening of the valve following the removal of the CLS Hi signal to conform to the FSAR commitment. An analysis has been initiated to insure that the valve functions in a conservative manner.

7. GENERIC IMPLICATIONS:

This event was identified at North Anna and found to be applicable at Surry.