05000287/LER-1983-005, Forwards LER 83-005/01T-0.Detailed Event Analysis Encl

Forwards LER 83-005/01T-0.Detailed Event Analysis Encl

ML20073N027
Person / Time
Site:	Oconee
Issue date:	04/13/1983
From:	Tucker H DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20073N030	List: 05000287/LER-1983-005, Forwards LER 83-005/01T-0.Detailed Event Analysis Encl 05000287/LER-1983-005-01, /01T-0:on 830314,supply Valve on Reactor Bldg Cooling Train B Failed.Caused by Main Feeder Breaker Tripping on Overcurrent.Breaker Reset,Overcurrent Trip Setting Increased & Setting Procedures Will Be Evaluated
References
NUDOCS 8304220359
Download: ML20073N027 (2)

LER-1983-005, Forwards LER 83-005/01T-0.Detailed Event Analysis Encl

Event date:
Report date:
2871983005R00 - NRC Website

text

E DUKE POWER GOMPANY P.O. BOX 33189 CHARLOTTE, N.C. 28242 og TE1.EPHONE HAL B. TUCKER

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(704) 373-4531 ww.m emmenomier April 13, 1983 23 IPR l9 12 y : 5i Mr. James F. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303 Re: Oconee Nuclear Station Docket No. 50-287

Dear Mr. O'Reilly:

Please find attached Reportable Occurrence Report R0-287/83-05. This report is submitted pursuant to Oconee Nuclear Station Technical Specification 6.6.2.1.b(2) which concerns operation in a degraded mode permitted 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.

Very truly yours, f8. G L p44 Hal B. Tucker JCP/php Attachment cc: Document Control Desk U. S. Nuclear Regulatory Commission Washington, D. C. 20555 INPO Records Center Suite 1500 1100 circle 75 Parkway Atlanta, Georgia 30339 Mr. J. C. Bryant

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NRC Resident Inspector Oconee Nuclear Station Mr. E. L. Conner, Jr.

Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555

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- or Duke' Power Company Oconee Nuclear Station Report Number: R0-287/83-05

Report Date: April 13, 1983 Occurrence Date: March 14, 1983 Facility:.0conee Unit 3, Seneca,-South Carolina Identification of Occurrence: -Unit 3 Reactor Building Cooling Train inoperable due to an inoperable-valve Conditions Prior to Occurrence:.100% FP Description of Occurrence: On March 14, 1983 at 1313,-the supply valve to the Unit 3 "B" Reactor Building Cooling Unit (RBCU) failed to open during an Engineered Safeguards (ES) test. The valve and the RBC train.were both declared inoperable, thus placing Unit 3 in a degraded mode per Technical Spec-ification 3.3.5.c.(2).

After several attempts to'open the valve proved unsuccess-ful,.the breaker was checked and found. tripped.

. Apparent Cause of Occurrence: The cause of this ine'ident was component failure.

The main feeder breaker to Valve 3LPSW-566 tripped on overcurrent during monthly -

testing which involves partially opening the valve by the generation of an Engineered Safeguards (ES) signal.' The overcurrent trip setting was found to

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be at the minimum setpoint, which is general practice after a valve motor has-been installed, which will allow the valve to operate. This is done to give the equipment the~ maximum protection possible.

Analysis of Occurrence: Two independent ES systems, the Reactor Building Spray (RBS) and the Reactor Building Cooling System, are designed to remove heat from the Reactor Building (RB) following a Loss of' Coolant Accident (LOCA). The~RBS System alone is capable of limiting the containment pressure,,after a LOCA, below the RB design pressure. A failure of 3LPSW-566 to open after a LOCA would only make the "B" RBCU inoperable. The "A" and "C" RBCUs would still be available to remove. heat.- The health and safety of the public were not compromised.

Corrective Action

The immediate corrective action involved having the main feeder breaker to the valve' motor operator reset, and the valve successfully

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tested. Later, ~ the valve motor operator was verified to be working properly.

The overcurrent. trip setting on the breaker was then increased from the minimum.

The practice of setting the overcurrent trip setting at the lowest possible value on ES valves will be evaluated.