05000266/LER-1979-011-01, /01T-0:on 790804,while Proceeding to Cold Shutdown Condition,Containment Integrity Was Briefly Violated.Caused by Faulty Interlock Allowing Inside Containment Door to Open When Outside Door Was Already Open

/01T-0:on 790804,while Proceeding to Cold Shutdown Condition,Containment Integrity Was Briefly Violated.Caused by Faulty Interlock Allowing Inside Containment Door to Open When Outside Door Was Already Open

ML19208A108
Person / Time
Site:	Point Beach
Issue date:	08/14/1979
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19208A107	List: 05000266/LER-1979-011, Forwards LER 79-011/01T-0 05000266/LER-1979-011-01, /01T-0:on 790804,while Proceeding to Cold Shutdown Condition,Containment Integrity Was Briefly Violated.Caused by Faulty Interlock Allowing Inside Containment Door to Open When Outside Door Was Already Open
References
LER-79-011-01T, LER-79-11-1T, NUDOCS 7909120582
Download: ML19208A108 (2)

LER-1979-011, /01T-0:on 790804,while Proceeding to Cold Shutdown Condition,Containment Integrity Was Briefly Violated.Caused by Faulty Interlock Allowing Inside Containment Door to Open When Outside Door Was Already Open

Event date:
Report date:
2661979011R01 - NRC Website

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LICENSEE EVENT REPORT CONTROL BLOCK l

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l lh PLEASE PRINT OR TYPE ALL REQUIRED INFCRMATION) 1 6

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8 60 61 DOCK ET NUMBER ed 69 EVENT DATE 74

'S REPORT DATE 80 EVENT OESCRIPTION AND PPOBABLE CONSEQUENCES h At 0615 hours0.00712 days <br />0.171 hours <br />0.00102 weeks <br />2.340075e-4 months <br />, 8-3-79, while proceeding to a cold shutdown condition I

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with reactor coolant system at 393 psig and 343 degrees, containment I

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[ integrity was briefly violated.

The violation occurred when the inside I o

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containment door was opened with the outside door already open.

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f tainment integri ty was quickly reestablished by shutting the inside doorp lTS 15.3.6.A.a requires that containment integrity not be violated unlessl o

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,the reactor is in a cold shutdown condition.

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]Ordinarilv the inside and outside doors are prevented from being opened l o

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In this instance the inter-I lock failed due to a roll pin falling out of a connecting rod in the j

mechanism.

The interlock was repaired and satisfactorily tested along l

with a qualifying air test of the personnel hatch by 2045 hours0.0237 days <br />0.568 hours <br />0.00338 weeks <br />7.781225e-4 months <br />,8-4-79 l

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ATTACHMENT TO LICENSEE EVENT REPORT NO. 79-011/0lT-0 Wisconsin Electric Power Company Point Beach Nuclear Plant Unit 1 Docket No. 50-266 At 0615 hours0.00712 days <br />0.171 hours <br />0.00102 weeks <br />2.340075e-4 months <br />, 08/03/79, while proceeding to a cold shutdown condition with the residual heat removal system lined up to the reactor coolant system (reactor coolant pressure 393 psig, temper-ature 343*F), containment integrity was briefly violated.

The violation occurred as the result of an interlock's failure in the containment personnel hatch operating mechanism which allowed the inside door to be opened with the outside door already open.

Containment integrity was quickly reestablished by shutting the inside door after ambient and in-containment pressures equalized.

Two persons were at the outside containment door at the time of the incident and two by the inner door.

No one was injured in the event although one of the persons standing by the outer door was drawn into the air lock by the inrushing air, and was knocked down in the process.

Ordinarily the inside and outside doors are prevented from

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being opened simultaneously by a mechanical interlock.

In this instance the interlock failed dae to a roll pin falling out of a connecting rod in the mechanism.

Apparently, the roll pin had loosened from use.

The interlock was repaired and satisfactorily tested along with a qualifying air test of the personnel hatch by 2045 hours0.0237 days <br />0.568 hours <br />0.00338 weeks <br />7.781225e-4 months <br />, 08/04/79.

To prevent recurrence, high strength tape has been strapped around the connecting rod over the roll pin as a temporary measure, pending review of alternatives by the Manager's Supervisory Staff.

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