05000270/LER-1981-014, Forwards LER 81-014/01T-0.Detailed Event Analysis Encl

Forwards LER 81-014/01T-0.Detailed Event Analysis Encl

ML20031B414
Person / Time
Site:	Oconee
Issue date:	09/18/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20031B415	List: 05000270/LER-1981-014, Forwards LER 81-014/01T-0.Detailed Event Analysis Encl 05000270/LER-1981-014-01, /01T-0:on 810821,during Routine Surveillance Testing,Electrical Penetration EMV-2 Not Pressurized w/SF6 Dielectric.Caused by Failure of Insulator Bushing.Bushing Repaired & Local Leak Rate Test Completed
References
NUDOCS 8110010350
Download: ML20031B414 (3)

LER-1981-014, Forwards LER 81-014/01T-0.Detailed Event Analysis Encl

Event date:
Report date:
2701981014R00 - NRC Website

text

_.

DUKE POWER COMPANY Powra ButtotNo 422 SouTu Cnuncu Stazzr, CauntorTz N. C. asa42 WI LLI AM O. PA R W E R J R.

/*C F Pm(Si O f NT TEttPwC*st; AngA 704

" ~ " " *" '

September 18, 1981

\\$

'N Mr. James P. O'Reilly, Director N

U. S. Suclear Regulatory Commission

[.

U s

Region II h

I

=

g

.i e 1.. n... :... r,; i.: 10101 SEP3 0 101 M.n r iet t.i Street. Siil t e 3100 Ob b "'OQ%p y

Re: Oconee Nuclear Station Docket No. 50-270 b

V

Dear Mr. O'Reilly:

Please find attached Reportable Occurrence Report R0-270/81-14. This report is submitted pursuant to Oconee Nuclear Station Technical Specifi-cation 6.6.2.1.a(3). which concerns a potential degradation in containment integrity, and describes an incident which is considered to be of no sig-nificance with respect to its effect on the health and safety of the public.

My letter of September 4, 1981, addressed the delay in the preparation of this report.

(

Ve truly yours, /

./

,D w.s lj.#cL' 't 'f William O. Parker, Jr. A JFK/php Attactnent cc: Director Mr. Bill Lavallee Office of Management & Program Analysis Nuclear Safety Analvsis Center U. S. Nuclear Regulatory Commission P. O. Box 10412 Washington, D. C. 20555 Palo Alto, California 94303 Mr. F. Jape Resident Inspector-NRC Oconee Nuclear Station 9

19' 59 8110010350 010918'

~

PDR ADOCK 05000270 8

PDR-

DUKE POWER C0l@ANY OCONEE UNIT 2 REPORT NUMBER:

270/81-14 REPORT DATE:

September 18, 1981 OCCURRENCE b..E:

August 21, 1981.

"Ar * !.!TY : Oconee Nuclear Statton. 1*n i t 2

?. n.. a.

mith C.3ro!in.i A : l i e. y 0 e WsTimlys i:

!. l c. t t t..i :

• nc t t.i t !..it A:

,i'..

6 : :

.itscovered empty and could not be repressurized with SF G"

6 CONDITION PRIOR TO OCCURRENCE:

100% F.P.

DESCRIPTION OF OCCURRENCE. At N 1030 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.91915e-4 months <br /> on August 21, 1981, routine surveillance testing identified that ENV-2 electrical penetration (Power Supply for 2A1 RCP) was not pressurized with SF6 dielectric. Attempts were made to repressurize the penetration but were unsuccessful. Unit power level was decreased, the 2A1 RCP was removed from service and the affected penetratien was then isolated. A constant pressure from the SF6 supply was applied to the penetration and a liquid leak detector was applied to the outside containment end of the penetration. No leaks were discovered.

Based on the facts that one containment building boundary was' intact, the low probability of propagation of the leak from one end of the penetration to the other, and a previous safety analysis which had determined that operation with one containment pressure boundary intact was acceptable, it Tr.s decided to reenergize the penetration, restart the 2Al RCP and escalate back to full power.

Additional precautions were taken which consisted of the following:

1.

A " pancake" probe (RM-14) was attached to the' penetration enclosure.

This probe was monitored by Operations personnt1.

Since the art ivf -

in the containment was significantly higher than that in the penetratt6n room, any leakage from the containment was expected to be indicated by the probe.

2.

From August 21-25, 1981, the affected penetration was purged once per day with SF.

Commencing on August 25, 1981 a continuous N2 purge was 6

initiated on the penetration. These actions were to minimize any moisture buildup within the penetrations.

On September 13, 1981, following chutdown of Unit 2 for unrelated problems, supply was again applied to the penetration a constant pressure from the SF6 and Performance personnel inspected the containment and of the penetration in an attempt to pinpoint the failure for Maintenance personnel to repair.

Following unsuccessful attempts to locate the source of the leaks inside the containment, the outside containment end was again inspected. After supply pressure, the source of the leak was determined to reducing the SF6

Report Number 270/81-14 Page 2 be a leaking insulator bushing on the outside containment end of the pere-tration. Apparently, the velocity of the leakage was aufficient to prevent the l'. quid leak detector from locating the leakage source on the initial inspection performed on August 21, 1981.

The insulator bushing was repaired and a local leak rate test was satisfactorily completed.

The i.ss.it one of the two cor.tainment boundaries of the electrical pene-n.t.!cred to be pot. nt t a l ;'r im.ir e ont.iinnen t.lecrad.it ion.ind

.s.

. ;... : t.. !. I e pis

.u.uit t.'

! ci hn 1..i I :ipe. i : 4..i t i..n e i. 'i..'. 1.. i ( ! ).

APPARENT CAUSE OF OCCURRENCE: The apparent cause of this occurrence was the failure of one of the insulator bushings on the outside containment end of the penetration.

ANALYSIS OF OCCURRENCE:

Subsequent leak rate testing of penetration confinned j

one of the two contairment boundaries was intact.

Since containment integrity was always intact during this occurrence, this incident is considered to be of no significance with respect to safe operation, and the health and safety of the public were not affected.

CORRECTIVE ACTION

The failed insulator bushing was repaired and a local lecle rate test was successfully completed.

i l