05000302/LER-1987-001, :on 861231,half-trip Signal Received on Main Steam Line Isolation Channel A.Caused by Faulty Light Emitting Diode (Led).On 870101,Tech Spec 3.0.3 Voluntarily Entered to Replace Led

:on 861231,half-trip Signal Received on Main Steam Line Isolation Channel A.Caused by Faulty Light Emitting Diode (Led).On 870101,Tech Spec 3.0.3 Voluntarily Entered to Replace Led

ML20209C790
Person / Time
Site:	Crystal River
Issue date:	01/29/1987
From:	Moffatt L, Eric Simpson FLORIDA POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
3F0187-25, 3F187-25, LER-87-001, LER-87-1, NUDOCS 8702040340
Download: ML20209C790 (4)

LER-1987-001, on 861231,half-trip Signal Received on Main Steam Line Isolation Channel A.Caused by Faulty Light Emitting Diode (Led).On 870101,Tech Spec 3.0.3 Voluntarily Entered to Replace Led

Event date:
Report date:
3021987001R00 - NRC Website

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j T.A.T_.,...~._.._...I On December 31, 1986, Crystal River Uni t 3 was operating at 39%

reactor power and producing 325 megawatts electric.

At approximately 2200 the Nuclear Operator received a half-trip signal on the "A" channel of the main steam line isolation (MSLI) for the "B" once through steam generator (OTSG).

The main steam isolation system is part of the Emergency Feedwater Initiation and Control (EFIC) System.

The operator determined the half-trip to be unwarranted and I

inadvertent.

Subsequent investigation identified a faulty light emitting diode (LED).

At 0025 on January 1, 1987, Technical Specification 3.0.3 was voluntarily entered and the EFIC actuation signal output breakers were temporarily opened to prevent spurious EFIC actuations while repairs were being performed.

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The f aul ty LED was repl aced.

The applicable post maintenance testing was satisfactorily, completed and the output signal breakers were then re-closed.

At 0042 on January 1, 1987, the EFIC system was returned to an operable status.and Technical Specification 3.0.3 was exited.

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EVENT DESCRIPTION

On December 31, 1986, Crystal River Unit 3 was operating at 39%

reactor power and producing 325 megawatts electric.

At approximately 2200 the licensed Nuclear Operator received a

h al f-tri p signal on the "A"

actuation c h a n rie l (initiated by "C"

cabinet) of the main steam line isolation (MSLI) for the "B"

once through steam generator (OTSG) [HX, ABl.

The main steam isolation system is part of the Emergency Feedwater Ini ti a ti on and Control (EFIC) System [JEl.

The operator determined the half-trip to be unwarranted-and inadvertent based upon instrumentation which indicated pertinent parameters were normal and stable.

Subsequent investigation identified a faulty light emitting diode (LED) [JE, XTl in the "C" EFIC cabinet.

Notifications were then made to the appropriate management personnel and the resident NRC inspector.

Based upon a previous Pl an t Review Commi ttee (PRC) evaluation of a similar event (LER 86-16); the man on call determined that during the repair activities the pl an t safety would be enhanced by temporarily disabling the automatic actuation function for both "A"

and "B" EFIC channels.

This would preclude the possibility of a

transient res ul ti ng from a

spurious EFIC actuation.

Thus permission was given to temporarily disable both EFIC channels (automatic functions only) and voluntarily enter Technical Specification 3.0.3.

The remote manual functions of the EFIC system remained completely operable from the control room.

At 0025 on January 1,

1987, Technical Specification 3.0.3 was voluntarily entered and one of the on-shift licensed operators was stationed as a dedicated operator at the EFIC controls.

Al thoug h the EFIC cabinets "A & B" remained energized, the actuation signal output breakers were temporarily opened to prevent spurious EFIC actuations while repairs were being performed.

The f aul ty LED was repl aced, the applicable post maintenance testing was sati sf actorily completed and the output signal breakers were then re-closed.

At 0042 on January 1,

1987, the EFIC system was returned to an operable status and Technical Speci fication 3.0.3 was exi ted.

CAUSE

The cause of the LED failure is unknown.

Technical Specification 3.0.3 was voluntarily entered to perform planned maintenance.

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Manually, all of the EFIC control functions were operable at all times.

All EFIC actuation parameters were observed to be within limi ts and EFIC was not actuated.

Al l repair activities were completed within the one hour time limit specified by Technical Specification 3.0.3.

This event did not have any impact on' the health and safety of the general public.

CORRECTIVE ACTION

The affected LED was replaced.

The root cause of the LED failure continues to be under review and evaluation by a special EFIC engineering task group which was established in early 1986.

PREVIOUS SIMILAR EVENTS

Eight previous similar events (voluntary entry into Technical Specification 3.0.3) have occurred at Crystal River Unit 3 and were reported in LERs 84-14 (two events), 85-01, 85-22, 85-29, 85-33, 86-11, and 86-16.

Four of these events were associated with the EFIC system and two of the four (85-22 and 86-16) were associated with LED failures.

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bb Power CORPOAATION January 29, 1987 3F0187-25 U.S. Nuclear Regulatory Commission Attn:

Document Control Desk Washington, DC 20555 Subject: Crystal River Unit 3 Docket No. 50-302 Operating License No. DPR-72 Licensee Event Report No. 87-001-00

Dear Sir:

Enclosed is Licensee Event Report (LER) No. 87-001-00 which is submitted in accordance with 10 CFR 50.73.

Should there be any questions, please contact this office.

Sincerely, 62 E. C. Simpson Director, Nuclear Operations Engineering and Licensing AEF/sdr Enclosure cc:

Dr. J. Nelson Grace Regional Administrator, Region II Mr. T. F. Stetka Senior Resident Inspector

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i GENERAL OFFICE: 3201 Thirty-fourth Street South (813) 866 5151 St. Petersburg, Florida 33733 P.O. Box 14042

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A Florida Progress Company