ML20037B520
| ML20037B520 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Oyster Creek  |
| Issue date: | 04/20/1972 |
| From: | Finfrock I JERSEY CENTRAL POWER & LIGHT CO. |
| To: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20037B519 | List: |
| References | |
| NUDOCS 8010140637 | |
| Download: ML20037B520 (2) | |
Text
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O JersefCentral Power & Light Company M ADtSON AVENUE AT PUNCH BOWL RO AD e MORRISToWN, N.J. 07960 e 539 6111 April 20, 1972
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L..,'..c 999 Dr. Peter A. Mo.ris, Director Division of Re..: tor Licensing
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Dear Dr. Morris:
Subject:
Oyster Creek Station Docket No. 50-219 Loss of Secondary Containment Integrity The purpose of this letter is to report to you a violation of a Limiting Condition for Operation in that Secondary Containment Integrity was not maintained as required by Specification 3.5.B.l.
of our Technical Specifications.
On April 11, 1972, during performance of a routine weekly surveillance test of isolation of the Recctor Building and initiation of the Standby Gas Treatment System due to simulated high radiation lec els on the Reactor Building Operating Floor and in the Reactor Building Ventilation Exhaust ducts, the supply dampers for the Reactor Building Ventilation System failed to close as required.
As a result of this failure, Secondary Containment was not in effect.
Isolation of the Reactor Building Ventilation System supply damper l's initiated by "b" contacts from the Reactor Building Ventilation System supply fans, SF1-12, SF1-13, and SF1-14 wired in series. however, due to an electrical problem with supply fan 1-13, which resulted in the discovery that the motor was shorted, its supply breaker was racked-out.
Thus, the logic control circuit for the da=pers was " opened", the normal situation with the fans in operation. When the remaining fans were tripped during the surveillance test conducted at 2:00 a.m. on
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April 11, 1972, the logic control circuit was still open, the damper control relays remained de-energized, and the dampers did not close.
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Dr. Peter A. Morris Page II April 20, 1972 The logic circuit was restored by disconnecting the =otor leads from the breaker and racking-in the breaker. At 9:20 a.m.
on April 11, 1972, an operability check of Reactor Building Isolation was conducted and proved to be satisfactory. A caution tag was placed at the fan control switches in the Control Room to notify operators that if a. supply fan breaker is racked-out,the Reactor Building supply damper isolation control logic is defeated unless a jumper is installed in the breaker cabinet. A similar caution note is being stenciled locally on the supply fan. breakers.
As noted in the FDSAR, the primary objective of the Secondary Containment System is to minimize ground level release of airborne radioactive materials and to provide for controlled elevated release of the building atmosphere under accident conditions. The conta~nment systems, Primary and Secondary, provide the principle mechanis= for mitigation of accident consequences. The off-site accident consequences, however, are relatively insensitive to the Reactor building in-leakage rate as long as the Standby Gas Treatment System can maintain the building at a vacuum.
In this particular instance, the supply and exhaust f a. ' tripped, the exhaust dampers closed, and the Standby Gas Treatment System was initiated. With the above situation, the air supply to the building was not only via the varicus in-leakage paths but also, and no doubt primarily, via the Reactor Building supply da=pers.
Any accident conditions postulated that require secondary containment in determining environ = ental releases would, under these conditions, have a second path permitting release of the Reactor Building air at approximately a 60-foot elevation.
In order to prevent a reoccurrence of this incident, a circuit design change will be implemented that will permit a Reactor Building supply fan breaker to be racked-out for =aintenance without defeating the Reactor Building supply damper isolation logic. Until this. design change can be implemented, a. standing order will be issued instructing plant personnel in the appropriate practice to be followed to avoid defeating the Reactor Building supply damper isolation logic.
Very truly yours, 0
J ll' Ivan R. Finfrock Jr.
Manager, Nuclear Generating Stations IRF/pk Enclosures cc: Mr. J. ?. O'Reilly, Director Division of Co=pliance, Region I
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