ML19319B744

RO NP-33-77-36:on 770727,emergency Air Lock Interior Door Found Open & Exterior Door Equalizing Valve Found Partially Open,Violating Containment Integrity.Caused by Loose Bolt in Door Linkage.Bolt Secured & Key Installed in Linkage

ML19319B744
Person / Time
Site:	Davis Besse
Issue date:	08/22/1977
From:	David Brown, Lingenfelter J TOLEDO EDISON CO.
To:
Shared Package
ML19319B635	List: ML19319B634 ML19319B744
References
NUDOCS 8001270205
Download: ML19319B744 (3)

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TOLEDO EDISON COMPANY

) DAVIS-3 ESSE UNIT ONE NUCLEAR POWER STATION

(/ . SUPPLEMENTAL INFORMATION FOR LER NP-33-77-36 DATE OF EVENT: July 27, 1977 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Violation of Containment integrity dua to inoperabi-lity of Emergency Escape Lock.

Conditions Prior to Occurrence: The plant was in Mode 3, with Power (MWT) = 0 and Load (MRE) = 0.

Description of Occurrence: At 1045 hours0.0121 days <br />0.29 hours <br />0.00173 weeks <br />3.976225e-4 months <br /> on July 27, 1977, personnel were unable to gain access to Containment through the exterior door of the Emergency Lock.

The Emergency Lock was inoperable, placing the station in the Action Statement of Technical Specification 3.6.1.3.

At 1230 hours0.0142 days <br />0.342 hours <br />0.00203 weeks <br />4.68015e-4 months <br />, upon investigation to determine why no access could be made through exterior door, Maintenance personnel and Chicago Bridge & 1ron (C3&I) representa-tive (supplier of the airlocks) found the interior door open, and the equalizing

(-'S valve for the exterior door partially open which violates Containment integrity E ) (Technical Specification 3.6.1.1). The Shif t Foreman was icnediately notified of

\- / the situation,and Maintenance Work Order MWO 77-1563 was issued to repair the Emergency Lock.

Designation of Apoarent Cause of Occurrence: A nut had worked off allowing a bolt to partially drop out of the door linkage on the interior door rendering it inopera-ble. The bolt enters the door linkage from the bottom side with the nut on top.

Due to interferences, the bolt would not enter the door linkage from the top side.

It was concluded that the nut was not securely tightened on the bolt and that numer-aus openings of the door caused the nut to work off allowing the bolt to partially fall out of door linkage.

A key was found sheared in the linkage for the equalizing valve. It was concluded that personnel attempting to enter Containment (not knowing that interior door was open) tried to force open the exterior door causing the key to shear,which allowed the equalizing valve to crack open enough to violate Containment integrity.

Analysis of Occurrence: Since plant had not yet reached initial criticality, there was no threat to the health and safety of the public or station personnel. Contain-ment access was avai~able through the personnel lock.

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,A TOLEDO EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION I

SUPPLEMENTAL INFORMATION FOR LER NP-33-77-36 PAGE 2 1

Corrective Action: At 1330 hours0.0154 days <br />0.369 hours <br />0.0022 weeks <br />5.06065e-4 months <br /> on July 27, 1977, the bolt to the door linkage on the interior door was secured and a new key was installed in the linkage to the equalizing valve.

The Emergency Lock was declared operable and Containment integrity restored which removed the station from the Action Statement of Technical Specifications

3. 6.1.1 and 3. 6.1.3.

3 Maintenance personnel working with the Chicago Bridge & Iron representative perfor:ed a preventative maintenance inspection and repair (tightened loose fittings, replaced damaged parts, etc.) on the emergency lock to prevent recurrence. The Maintenance Engineer will implement a routine preventative maintenance program to further prevent recurrence.

Failure Data: Containment integrity was previously violated on July 24, 1977 (NP-33-77-35) due to a combination of planned action and personnel error in the Personnel Air Lock.

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