05000287/LER-1981-007, Forwards LER 81-007/03L-0.Detailed Event Analysis Encl

Forwards LER 81-007/03L-0.Detailed Event Analysis Encl

ML20030C214
Person / Time
Site:	Oconee
Issue date:	04/28/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20030C215	List: 05000287/LER-1981-007, Forwards LER 81-007/03L-0.Detailed Event Analysis Encl 05000287/LER-1981-007-03, /03L-0:on 810329,inner Door Seal of Reactor Bldg Personnel Lock Found to Leak at Rate Greater than That Allowed by Procedure.Caused by Faulty Installation of Strong Backs.Gasket Shinned & Strong Backs Reinstalled
References
NUDOCS 8108250524
Download: ML20030C214 (2)

LER-1981-007, Forwards LER 81-007/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2871981007R00 - NRC Website

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• ' ' U C ;J ; 4 Powza Bu Lorno 4c2 Sourn Cucacu Srazzi, CitAatmTz, N. C. 28a42

i p.a.y 4 gn.g, April 28, 1981 w3WM O. PA R M E R, J R.

Tgttemong Anga 704 v cr Pats.orme 373-4083 Svtam PaoDuCHON Q, dst / s f

j N/(g Mr. James P. O'Reilly, Director g

2 N,g. y',I tb U. S. Nuclear Regulatory Commission

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Region II 101 Marietta Street, Suite 3100 A

Atlanta, Georgia 30303 9

.Q*g l'r' er 4

Re: Oconee Nuclear Station Qf j

O Docket No. 50-287

Dear Mr. O'Reilly:

Please find attached Reportable Occurrence Report RO-287/81-07. This report is submitted pursuant to Oconee Nuclear Station Technical Spec-ification 6.6.2.1.b(2), which concerns operation in a degraded mode per-mitted by a limiting condition for operation and describes an incident which is considered to be of no significance with respect to its effect on the health and safety of the public.

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truly yours,

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• _e William O. Parker, Jr.

JLJ/mwk Attachment Mr. Bill Lavallee

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cc: Director Office of Management & Program Analysis Nuclear Safety Analysis Center l

U. S. Nuclear Regulatory Commission P. O. Box 10412 Washington, D. C.

20555 Palo Alto, California 94303 l

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DUKE POWER COMPANY OCONFE UNIT 3 Report Number: R0-287/81-07 Report Date: April 28, 1981 Occurrence Date: March 29, 1981 Facility: Oconee Unit 3, Seneca, South Carolina Identification of Occurrence: Reactor Building Personnel Hatch Inner Door Inoperable Conditions Prior to Occurrence:

100% FP Description of Occurrence: During performance of the Reactor Building Personnel Lock Leak Rate Test, the inner door seal was found to leak at a rate greater than that allowed by the procedures. The inner hatch was declared inoperable at 0400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br /> on March 29, 1981. This constitutes operation in a degraded mode per Tech-nical Specification 3.6.3 and is thus reportable pursuant to Technical Specifica-tion 6.6.2.1.b(2).

Apparent Cause of Occurrence: The apparent cause of this incident was faul'ty in-stallation of the strong backs which resulted in an inadequate seal of the inner door gasket.

The leak, being found on the lower ri;ht hand corner, suggests that the strong backs in that corner were looser than the others. The looseness could be caused by the bolting torque not being converted to bolt tension,because of thread friction.or by bolt load on this strong back having been reduced by neigh-boring strong back bolts as they are tightened.

l Analysis of Occurrence: Because of the arrangement of this door, any build up of l

pressure in the Reactor Building would cause the door to seal tighter, effectively reducing, if not stopping, the leak. The outer door was operable during the tLne I

that the inner door was inoperable. The double seal design of the outer door would have stopped any release from the Reactor Building of radioactive materials in case of an accident, thus protecting the health and safety of the public.

Corrective Action

Immediate correctf.ve action taken involved shimming the gasket, reinstalling the strong backs, and retesting the seal.

Changes will be made to the strong back in,tallation procedures, " Installation and Removal of Strong Backs on Personnel Airlock", to provide for the following:

(1) Threads on strong back bolts will be cleaned and lubricated with either Moykcte Grapid Spray, Never Leez Pure Nickel Special, or Neolube.

(2) Bolts will be torqued in an alternating sequence as would any pressure vessel flange.

(3) At least one check pass will be made after the first torque sequence is completed.