ML20090D390
| ML20090D390 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 09/07/1973 |
| From: | Bartlett J NIAGARA MOHAWK POWER CORP. |
| To: | Skovholt D US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| 8843, NUDOCS 8302280065 | |
| Download: ML20090D390 (2) | |
Text
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s NIAGARA MOHAWK POWER CORPORATION NtACARA MOHAWK soo eme soutevano west 12)
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9 Mr. Donald J. Skovholt Assistant Director for Reactor Operations Division of Reactor Licensing United States Atomic Energy Commission Washington, D. C.
20545 Re:
Provisional Operating License: DPR-17 Docket No.: 50-220
Dear Mr. Skovholt:
Pursuant to your request, we are reporting as an abnormal occurance the loss of the stack ga:, monitors for a period of approximately 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> on June 26, 1973.
The plant' was starting up following the Spring refueling outage with the reactor at approximately 1460 MWt. Reactor output was being increased slowly in an attempt to precondition the fuel' assemblies and maintain the future stack gas release rate at as low a value as possible.
Stack gas activity at this time was approximately 8500 pCi/see well within all limits. There are two IcVels of continuous monitoring of the radioa'ctivity level of the effluent gases removed from the main condenser by the steam jet air-ejector system. The Off-gas monitors which were continually monitoring the radioactivity level of the gaseous effluent which is eventually released to the stack, are located prior to the holdup pipe and the stack. Using information from the off-gas monitors the stack release rat-un be determined. The stack gas monitors continuously monitor the ace fi:- of the gas released thru the stack.
These monitors see the r.AH at
.ty level of the same gas as the off gas monitors after a ho. ty..
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/ minutes and dilution of the gas with ventilation air from the plant.
At 1745 hours0.0202 days <br />0.485 hours <br />0.00289 weeks <br />6.639725e-4 months <br /> #12 stack sample pump tripped and could not be restarted. (Subsequent investigation revealed a bound motor).
- 11 stack sample pump was out of service and not piped-up at this time, awaiting an oil reservoir jar. The reservoir jar was leaking and although the pump would operate it would require ce stant monitor of the oil level.
- 11 stack sample pump was piped up and placed in service at 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br />.
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Mr. Donald J. Skovholt September 7, 1973 U.S. Atomic Energy Commission During the period of time the stack gas monitors were out of service the off gas monitors showed only a variation of 4 Mr/hr.
It is important to note that the stack gas monitors provide only an alarm function. The off gas monitors which were functioning normally, provide for automatic closure of the isolation valve in the off gas line at the maximum release rate and their operation is the limiting condition for operation. The information from the stack gas monitoring system is used in preparation of plant radioactive effluent reports and demonstrating compliance with maximum release rates.
Before the stack release rato would have reached a point where the health and safety of the general public would have been endangered, the off gas monitors would have isolated the off gas line to the stack.
To prevent similar future occurances of this event a third sampling pump will be used as a spare and employed whenever one of the two normal sample pumps are out of service.
Very truly yours, e>
6M (W M -
()JamesBartlett Executive Vice President Operations and Engineering JB:cm I
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