05000369/LER-1981-036, Forwards LER 81-036/01T-1.Detailed Event Analysis Encl

Forwards LER 81-036/01T-1.Detailed Event Analysis Encl

ML20009C331
Person / Time
Site:	McGuire
Issue date:	05/05/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20009C332	List: 05000369/LER-1981-036, Forwards LER 81-036/01T-1.Detailed Event Analysis Encl 05000369/LER-1981-036-01, /01T-1:on 810414,during Mode 3 Failure of One Seal of Lower & Upper Personnel Air Lock Occurred.Caused by Pressure Exceeding 55 Psi & Door Not Properly Aligned.Seal Inflation Reduced & New Seals Installed
References
NUDOCS 8107200468
Download: ML20009C331 (3)

LER-1981-036, Forwards LER 81-036/01T-1.Detailed Event Analysis Encl

Event date:
Report date:
3691981036R00 - NRC Website

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May 5, 1981 373.o.3

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Mr. James P. O'Reilly, Director U. S. Nuclear Regulatory Commission

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Dear Mr. O'Reilly:

Please find attached Revision 1 to Reportable Occurrence Report R0-369/81-36.

This report concerns loss of containment integrity due to multiple personnel air lock seal failures.

This incident was considered to be of no significance with respect to the health and safety of the public.

Very truly yours,

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2 William O. Parker, Jr.

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Director Mr. Bill Lavallee Office of Management & Program Analysis Nuclear Safety Analysis Center U.S. Nuclear Regulatory Commission P. O. Box 10412 Washington, D. C.

20555 Palo Alto, CA 94303 f]

41 8107200468 810505 PDR ADOCK 05000 S

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McG'.%E FUClJAR STATION INCIDENT REPORT Report Number:

81-36 Report Date:

April 27, 1981 Occurrence Date: April 14, 1981 Facility:

McGuire Unit 1 Identification of Occurrence:

Seals on the upper and lower personnel air locks failed.

Conditions Prior to Occurrence: Mode 3 Description of Occurrence: On April 14, 1981 failure of one seal of the lower personnel air lock and one seal of the upper personnel air lock occurred. Both of these seals failed while the door was closed.

Apparent Cause of Occurrence:

The seals were designed and manufactured for an operating pressure of 55 to 60 psi.

The operating pressure being used was approximately 90 psi.

In addition, the seals were not designed to be inflated while unconstrained.

This puts too much stress on the inner fabric eventually causing it to tear.

The doors were not properly aligned, so that even if the door was closed when the seal was inflated, the seal was effectively uncon-strained.

This combination of circumstances led to repeated failures of the seals.

Analysis of Occurrence:

The lower personnel air lock auxiliary building door was partly open when a seal on the reactor building door failed.

The auxiliary building door stopped, as designed.

The interlock was overriden to close and secure the door. Nbintenance personnel were sent through the upper air lock to work on the lower air lock.

While they were inside containment, a seal on the upper air lock auxiliary building door failed.

The NRC was informed that containment integrity would have to be violated to allow maintenance personnel to exit containment.

This constituted a reportable occurrence pursuant to Technical Specification 3.6.1.1.

Corrective Action

The lower personnel air lock seal was replaced and immediate corrective action was taken to decrease the probability of further seal failures.

Seal inflation pressure was reduced from 90 psi to 60 psi. A limited access program was instituted so that personnel could only enter or exit the containment once an hour.

Discussions with the manufacturer resulted in the following long term solution.

Seal inflation pressure will be maintained at 60 psi.

The doors will be re-aligned and shim plates will be added to eliminate any large sealing gaps.

New seals, designed for an operating pressure of 90 psi, will be installed as soon as possible.

Delivery is expected within two weeks.

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Safety Analysis

The only safety impact occurred when the containrent integrity was violated.

However, since only new fuel is in the core, the health and safety of the public were not affected.

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