ML17037C130

Letter Reporting an Orderly Shutdown on July 27, 1972 Due to Increasing Recirculation System Valve Packing Leakage within the Drywell

ML17037C130
Person / Time
Site:	Nine Mile Point
Issue date:	08/01/1972
From:	Schneider F Niagara Mohawk Power Corp
To:	Skovholt D US Atomic Energy Commission (AEC)
References
Download: ML17037C130 (6)

Text

AEC DISTRIBUTION FOR PART 50 DOCKET MATERIAL TEMPORARY FORM FI DATE OF DOC: DATE REC'D LTR iRMO RPT FROM'iagara Mohawk Power Corpo tion To:

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J. Schneider Mr. Skovholt 13202 8<<1-72 ORIG CC ('ENT 8.-4 2

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AEC PDR SENT LOCAL PDR CLASS: U PROP INFO No CYS REC'D DOCKET No:

0 220 DE IPTION: ENCLOSURES:

Ltr reporting an incident on 7-27-72~

regarding an increasing recirculation syst va5W packing leakage within the drywell."

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August 1, 1972 Mr. Donald J. Skovholt Assistant Director for Reactor Operations Division of Reactor Licensing 8 United States Atomic Energy Commission Washington, D. C. 20545

Dear Mr. Skovholt:

Re: Provisional Operating License: DPR-17 Docket No.: 50-220 Appendix A (Technical Specifications 3.3.1 a and 3.3.1 b) of Provisional Operating License DPR-17 for Nine Mile Point Nuclear Station, Unit Ol states:

3.3.1 a "After completion of the startup test program and demonstration of plant electrical output, the primary containment atmosphere shall be reduced to less than five percent oxygen with nitrogen gas whenever the reactor coolant pressure is greater than 110 psig and the reactor is in the power operating condition, except as. specified in "b" below."

3.3.1 b "Within the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period subsequent to increase of the reactor coolant pressure above 110 psig whenever the reactor is in the power. operating conditj.on, the containment atmosphere oxygen concentration shall be reduced to less than five percent by weight and maintained in this con-dition. Deinerting was commenced 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> prior to a major refueling outage or other scheduled shutdown."

An orderly shutdown of Unit 81, Nine Mile Point Nuclear Station was begun on July 27, 1972 due to increasing recirculation system valve packing leakage within the drywell. Following repacking of the affected valves, the unit was restarted on July 30, 1972 and reached 110 psig at 0700 that day.

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0 Mx. Donald J. Skovho1t Page 2 United States Atomic Energy Commission An agreement had been made prior to shutdown with National Cylinder Gas, a nitrogen gas supplier in Conshohocken, Pa. for delivery of two trucks of nitrogen on July 30, 1972. Normal inerting requires 4 - 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and could easily be accomplished that day, well within the required 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. However, unknown to station personnel, the gas supplier was having difficulty in obtaining drivers for the necessary two trucks of nitrogen. The startup of the Unit beyond 110 psig continued, based upon the prior agreement that nitrogen would be arriving for inerting that day. At midnight, July 30, 1972 with no nitrogen for inerting on site, it was deemed necessary by station personnel to hold thermal power to 1200 MN(t) and not continue with the normal scheduled startup until the drywell was inerted.

The first truck of nitrogen arrived at the station the morning of July 31, 1972 and inerting began immediately. The drywell atmosphere was reduced to less than five percent oxygen at 134S that day, reaching 3.9 percent at 1400.

The start up scheduled then continued.

The drywell atmosphere remained within specification following inerting and with the arrival of the second truck late in the evening, July 31, 1972 was reduced to its present level of one percent by weight of oxygen.

Very truly yours, F. J. Schn'eider Vice President e Operations

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