ML20005B688

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Responds to 810715 Ltr Re Butterfly Isolation Valve Leakage Integrity Tests.Due to Design of Subatmospheric Containment Used at Facility,Svc Conditions Do Not Warrant More Stringent Testing Requirements.Test Means Will Be Forwarded
ML20005B688
Person / Time
Site: Beaver Valley
Issue date: 08/27/1981
From: Carey J
DUQUESNE LIGHT CO.
To: Varga S
Office of Nuclear Reactor Regulation
References
NUDOCS 8109010224
Download: ML20005B688 (3)


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August 27, 1981 ISfrector of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Attn: Mr. Steven A. Varga, Chief q\ g ,)

Operating Reactors Branch No. 1 dy Division of Licensing Washington, DC 20555 97

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Reference:

Beaver Valley Power Station, Unit No. 1 Docket No. 50-334, License No. DPR-66 g y hf Butterfly Isolation Valve Leakage Integrity Tests ,,

Centlemen: 4Wy We have carefully reviewed your letter of July 15, 1981, and the design i

and test data related to the purge supply and exhaust valves. Based upon our review and consideration of the unique nature in the design of the sub-atmospheric containment used at Beaver Valley, we believe that the service conditions to which these valves are exposed do not warrant more stringent testing requirements than those already in effect. We propose that we continue with our present Type C Test Program for these dampers which we find adequate for the following reasons:

1. The current test data indicates total penetration leakage at these valves to be:

Purge Supply Dampers 1.118 SCF/ DAY Purge Exhaust Dampers 1.65 SCF/ DAY Air Ejector Isolation 35.84 SCF/ DAY

2. The location and system design for these dampers is such that they are not subjected to severe environmental conditions or significant seasonal temperature vi.riations. They are only used during cold shutdown and, therefore, are not cycled frequently enough in an 18 month test period to degrade the resilient seats and cause excessive leakage. The Technical Specifications limit the containment temperature during operation to 75-105F.

l 3. A subatmospheric containment, by design, provides the operator continuous monitoring of containment leakage from all atmospheric sources. The operator is provided with alarms and in.lications that enable him to rapidly detect conditions indicative of gross inleakage to the containment.

4. The Containment Vacuum Pumps' capacity is typically low enough (%5 scfm) that continuous operation would be required to compensate for excessive leakage from any source. This fact in itself alerts the operator to the potential of a deteriorating condition which would initiate identification of the source. pfoOj 1

/l0 8109010224 810827 PDR ADOCK 05000334 P PDR

Beaver Valley Power Station, Unit No. 1 Docket No. 50-334, License No. DPR-06 Butterfly Isolation Valve Leakage Integrity Tests Page 2

5. The Containment Depressurization System by design, returns the containment to a subatmospheric condition within 60 minutes after a DBA and therefore, these dampers would not be a source of continuous discharge to the environment following a LOCA.
6. The containment air partial pressure limit is governed by the Technical Specifications and is calculated and logged every 12 hores. Integrated readings are also taken each shif t as a means for determining gross leakage rates from the containment.

We feel that existing controls and available instrumentation alert super-vision to this type of degradation in a more expeditious manner than relying on semi-annual testing of these penetrations.

We are presently awaiting vendor information on expec*ed seat life for .

these valves under our specified service conditions, prior to implementing a specific test program.

t If our proposal is satisfactory to your staff we will implement administrative requirements to test the referenced penetrations on .2 priority basis during any period when excessive leakage into the containment has been identified.

Our test means and action level will be forwarded under separate cover contingent on your response to our submittal.

Ve ry tr y yours, t

J. J. Carey l

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O Beaver Valley Power Station, Unit No. 1 Docket No. 50-334, License No. DPR-66 Butterfly Isolation Valve Leakage Integrity rests Page 3 cc: Mr. D. A. Beukman, Resident Inspector U. S. Nuclear Regulatory Commission Beaver Valley Power Station Shippingport, PA 15077 U. S. Nuclear Regulatory Commission c/o Document Management Brat.ch Washington, DC 20555

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