05000395/LER-1985-001, :on 850216 & 27,due to Failure of Rod Control Sys,Reactor Shut Down,Per Tech Spec 3.1.3.Caused by Low Output from Pulser Oscillator Circuit & Erratic Output of Supervisory Buffer Memory Circuit,Respectively

:on 850216 & 27,due to Failure of Rod Control Sys,Reactor Shut Down,Per Tech Spec 3.1.3.Caused by Low Output from Pulser Oscillator Circuit & Erratic Output of Supervisory Buffer Memory Circuit,Respectively

ML20128L632
Person / Time
Site:	Summer
Issue date:	05/21/1985
From:	Dixon O, Koon A SOUTH CAROLINA ELECTRIC & GAS CO.
To:	NRC OFFICE OF ADMINISTRATION (ADM)
References
LER-85-001, LER-85-1, NUDOCS 8505310402
Download: ML20128L632 (4)

LER-1985-001, on 850216 & 27,due to Failure of Rod Control Sys,Reactor Shut Down,Per Tech Spec 3.1.3.Caused by Low Output from Pulser Oscillator Circuit & Erratic Output of Supervisory Buffer Memory Circuit,Respectively

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)
3951985001R00 - NRC Website

text

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NRC Feren 33g U S. NUCLElu REGULATORY COnesseBION

^3I APPROVED oms NO 3150 4 104 LICENSEE EVENT REPORT (LER)

F ACILeTV NAME III DOCKET NUMSER (2) 8 AGE G Virgil C. Summer Nuclear Station ois;oioio;3 9 5 i lorl 0, 3 i i R$d Control System Failure EVENT DATE 196 LER NUMBER (s}

REPORT DATE (7)

OTHER FACILITIES INVOLVED (S)

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AesTR ACT (Lmt to t400 soecen n e. epares*ere'v tow sone?e soece troewertree Imeel 1161 On February 16 and 27, 1985, the reactor was shutdown in accordance with Action Statement (b) of Technical Specification 3.1.3, " Moveable g

Control Assemblies," due to failure of the Rod Control System.

The failure on February 16 was attributed to a low output from a pulser oscillator circuit, and the failure on Feburary 27 was due to an erractic output of the supervisory buffer memory circuitry.

The pulser oscillator circuit was calibrated, and a new supervisory buffer memory card was installed.

There were no adverse consequences due to this event.

The unit was manually tripped af ter reducing reactor power.

All safety systems functioned as designed with the exception of one Feedwater Isolation Valve (FWIV).

After closure, FWIV-1611A cycled open approximately one half inch.

The Licensee believes the cycling is due to an internal hydraulic leak.

Repairs to the valve will be made during the next outage of sufficient duration, depending on the availability of spare parts.

In the interim, a non-permanent modification has been installed to insure feedwater isolation.

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• • paovEo Ous No. 3 iso-cio4 EXPIRES 8/3185 FACILITY NAME Ill DOCKET NUMBER (2)

LER NUMBER 16)

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TEXT (# more ap.ce as segunoct use -

' NMC Form J66Ns1(17)

At approximately 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br />, February 16, 1985 with the Plant at 100%

power, the Rod Control System was declared inoperable when the control rods failed to respond to a demand signal during manipulation of control rods for Delta Flux control.

Reactor power was reduced to 3% and the reactor was manually tripped at 1448 hours0.0168 days <br />0.402 hours <br />0.00239 weeks <br />5.50964e-4 months <br /> in accordance with Action Statement (b) of Technical Specification 3.1.3, " Moveable Control l

Assemblies."

The Licensee immediately requested the manufacturer provide a technical representative to assist maintenance personnel in repair of the Rod Control System.

Deficiencies identified during trouble-shooting were a low output voltage (249V versus 260V) of the Control Rod Drive Motor-Generator, and the pulser oscillator circuit was not in calibration.

The output voltage of the Motor-Generator was corrected.

The pulser oscillator card from the part-length rod control cabinet, which is not used on this unit, was installed and calibrated.

A test procedure was written and approved to allow movement of the control rods thirty (30) steps out and in, while running current traces of the rod coils.

A current trace on a rod coil in each group and a trace of the pulser oscillator output was run and found to be satisfactory.

It was determined that the rod motion failure was due to the out-of-calibration pulser oscillator card.

The applicable surveillance test was satisfactorily performed and the system declared operable at 0530 hours0.00613 days <br />0.147 hours <br />8.763227e-4 weeks <br />2.01665e-4 months <br />, February 18, 1985.

At 0135 hours0.00156 days <br />0.0375 hours <br />2.232143e-4 weeks <br />5.13675e-5 months <br />, February 27, 1985 with the Plant at 100% reactor power, while attempting to manipulate control rods for Delta Flux control, a rod control system failure urgent alarm annunciated and would not clear.

At 0705 hours0.00816 days <br />0.196 hours <br />0.00117 weeks <br />2.682525e-4 months <br /> with reactor power at 10%, the reactor was manually tripped in accordance with Technical Specifications.

The Licensee again requested the manufacturer provide a technical representative to assist maintenance personnel.

It should be noted that on this failure the alarm would not clear.

On the previous failure of February 16, the alarm cleared prior to the investigation by maintenance personnel into the failure.

The problem was determined to be with the direction (In/Out) signal.

The system was aligned to allow withdrawal of the control rods to 30 steps and to manually step the rods "In" to create the error and to allow tracing of the error signal.

The error signal was found to be originating at the output of the supervisory buffer memory card.

The card was replaced, and the system was satisfactorily tested and declared operable at 0225 hours0.0026 days <br />0.0625 hours <br />3.720238e-4 weeks <br />8.56125e-5 months <br />, February 28, 1985.

There were no adverse consequences due to this event.

The Licensee complied with the action as required by the Technical Specifications.

The Licensee plans no additional corrective action associated with the Rod Control System other than scheduled maintenance and testing.

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NRC F.rm 306A U 5. NUCLEGO CEQuLOTORY COMMISSION LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Areaoveo oMe No. airo-oio4 EXPIRES. 8/31/B$

FACILITY NAME 11)

DOCKET NUMSER (2)

LER NUMBER (6)

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Virgil C. Summer Nuclear Station o ls jo lo jo l 3l9 l5 8l5 0 l0 l 1

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. m v aew,> nn Un each reactor trip, all safety systems functioned as designed with the exception of Feedwater Isolation Valve 1611A.

After closure, the valve cycled open approximately one half inch, then cycled closed.

The period of the cycling was approximately thirty-two seconds.

The problem is believed to be an internal hydraulic leak.

Repairs will be made during the next outage of sufficient duration, depending on the availability of spare parts.

In the interim, a non-permanent modification has been installed that trips the Feedwater Booster Pumps for feedwater isolation.

4 C PORM 3664

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SOUTH CAROLINA ELECTRIC & GAS COMPANY post ospica 7se COLuusiA. SoufH CAROLINA 29218 o. w. o,noN. sa.

May 21, 1985 WCr PatslDENT NUCLEAn OpenartoNs U. S '. Nuclear Regulatory Commission Document Control Desk Washington, DC-20555 SU BJE CT :

Virgil C.

Summer Nuclear Station Docket No.'50/395 Operating License No. NPF-12 LER 85-001, Revision 1

Dear Sir:

Attached is Revision 1 to Licensee Event R' port #85-001 for the e

Virgil C.

Summer Nuclear Station.

This revision is being submitted to provide corrected information.- This-report was p r ev i ou s l y submitted on March 18, 1985, in accordance with the requirements of 10CFR50.73(a)(2)(i).

Sh ou ld there be any questions, please call us at y ou r convenience.

Very truly yours, O.

W.

Dixon, Jr.

RJB:0SB/ led Attachment ec:

V.

C.

Summer J.

F. Heilman T.

C.

Nichols, Jr./O.

W.

Dixon, Jr.

C.

L.

Ligon (NSRC)

E.

H.

Crews, Jr.

K.

E.

Nodland E.

C.

Roberts R.

A.

S t ou g h W.

A.. Williams, Jr.

C.

Pe r c iv a l D.

A.

Nauman C.

W.

Hehl J.

Nelson Grace J.

B.

Knotts, Jr.

Group Managers INPO Record s Center O.

S.

Bradham ANI Lib rary C.

A.

Price NPCF S.

R.

Hunt File

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