05000369/LER-1981-011, Forwards LER 81-011/03T-0

Forwards LER 81-011/03T-0

ML20008E875
Person / Time
Site:	McGuire
Issue date:	03/04/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20008E876	List: 05000369/LER-1981-011, Forwards LER 81-011/03T-0 05000369/LER-1981-011-03, /03T-0:on 810210,both Pressure Seals on Inner Door of Lower Personnel Air Lock Failed.Caused by Hole in One Seal & Bubble in Other Seal.Seals Replaced & Returned to Manufacturer
References
NUDOCS 8103100426
Download: ML20008E875 (3)

LER-1981-011, Forwards LER 81-011/03T-0

Event date:
Report date:
3691981011R00 - NRC Website

text

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Dirun POWER COSIP.WY Powen Dtut. DING 422 Socin Cut;ucu SrnEnr.CuratorTz N C. coa w ww4 4 c.

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March 4, 1981

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• r Aata 'i S e t e.e **GCwC*04 3?F4793 Mr. J. P. O'Reilly, Director

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U. S. Nuclear Regulatory Commission

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Region II

/p 101 Marietta Street, Suite 3100 Atlanta, Georgia' 30303 g

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(h Re: McGuire Nuclear Station Unit 1

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Docket No. 50-369

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Dear Mr. O'Reilly:

Please find attached Reportable Occurrence Report R0-369/81-11. This report concerns failure of both pressure seals on the inner door of the lower person-nel air lock. This incident was considered to be of no significance with respect to the health and safety of the public.

- This report was inadvertently categorized as a 30-day report whereas it should have been a 14-day report. Consequently, this report is being submitted 8 days late.

V [y truly yours/,

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[x 7 William O. Parker, Jr.k ).

RNO:ses cc:' Director Mr. Bill Lavallee Office of Management and Program Analysis Nuclear Safety Analysis Center

U.-S. Nuclear Regulatory Commission P. O. Box 10412

. Washington, D.- C.

20555.

Palo Alto, California 94303' 4

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MCGUIRE NUCLEAR STATION INCIDENT REPORT Report Number: R0-369/81-il Report Date: February 17, 1981 Occurrence Date: February 9, 1981 Facility: McGuire Unit 1 Identification of Occurrence: Failure of Both Pressure Seals on the Inner (Reactor Building Side) Door of the Lower Personnel Air Lock Condition Prior to Occurrence: Mode 6, Initial Fuel Losding Description of Occurrence:

Both pressure seals on the inner door of the lower personnel air lock failed.

One seal had a hole in it and could not be inflated. The other could be inflated but a " bubble" indicated that total failure was imminent.

Apparent Cause of Occurrence:

It appears that ply separation was the caust of the seal failure.

McGuire has had problems with ply separation in an earlier design seal used on the personnel air locks. Eventually all of the old design seals were replaced. Seals made by the new design, with the fabric surrounding the infla*.ed section only, have been installed on all four of the Unit 1 person-nel air lock doors (eight seals) with only two seal failures.

Both defective seals were installed on the same door and at the same time.

The bad seals had as few or fewer cycles than any of the others which are still operating properly.

Analysis gj Occurrence:

The failure of both seals on one door is a loss of one out of two means of isolating the containment vessel through the lower personnel air lock. Outer (auxiliary building side) door seals remained operable. At the time of the occurrence, fuel movement was completed and the reactor head had been installed.

Containment integrity was no longer required per Technical Specification 3.9.4.

Since the fuel loading involved only new fuel and no fuel movement was underway the tire of the occurrence, health and' safety of the public were not affected.

at A similar occurrence during power operation would require locking the outer door closed until the inner door was repaired or the unit was brought to cold shutdown (Technical Specification 3.6.1.3).

The inner door on either personnel air lock

- probably could not be repaired without opening the outer door on the same per-sonnel air lock. Since this is not allowed during power operation, the unit would eventually have to be shutdown to repair the' door. A failure of one or more seals on each door of.a personnel air lock could compromise-the operability and possibly the integrity of the lock requiring the immediate_ shutdown of the unit.

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Corrective Action

The immediate carrective action was to replace the two defective seals uith Several courses of action will determine the permanent solution.

new ones.

The defective seals will be returned to the manufacturer who will attempt to determine if the problem is limited to one batch of seals, if the problem is generic to the manufacturing process, or if the problem is random in the manufacturing process.

Duke power Design Engineering and Quality Assurance will attempt to devise testing and/or inspection procedures which will prevent the purchase of additional defective personnel air lock door seals. An investigation will be made to determine which seals, if any, now installed en McGuire personnel air locks or in McGuire stock came from the same batch as the defective seals.