ML18153C111

LER 90-001-00:on 900108,one of Three RCS Average Temp Channel Inputs to Reactor Protection Sys Not Declared Inoperable After Deviating from Other Two Channels.Caused by Faulty Summator.Summator replaced.W/900205 Ltr

ML18153C111
Person / Time
Site:	Surry
Issue date:	02/05/1990
From:	Kansler M VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
90-001, 90-1, LER-90-001-01, LER-90-1-1, NUDOCS 9002230051
Download: ML18153C111 (4)

Text

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• VIRGINIA ELECTRIC AND POWER COMPANY Surry Power Station P.O. Box 315 Surry, Virginia 23883 February 5, 1990 U.S. Nuclear Regulatory Commission Serial No.: 90-001 Document Control Desk Docket No.: 50-281 Washington, D.C. 20555 License No. : DPR-37 Gentlemen:

Pursuant to Surry Power Station Technical Specifications, Virginia Electric and Power Company hereby submits the following Licensee Event Report

-for Unit 2.

REPORT NUMBER ..

90-001-00 This report has been reviewed by the Station Nuclear Safety and Operating Committee and will be reviewed by Corporate Nuclear Safety.

Very truly yours,

[t~

- ~

M. R. !Cansler -

Station Manager Enclosure cc: Regional Administrator Suite 2900 101 Marietta Street, NW Atlanta, Georgia 30323 9002230051 900205 PDR ADOCK 05000281 8 PDC

POW 28-06-01 NIIC Form :l~ U.S. NUCLEAR REGULATORY COMMISSION (S-83)

.,I LICENSEE EVENT REPORT (LERI APPROVED 0MB NO. 316G-0104 EXPIRES: 8/31/88 FACILITY NAME (11 DOCKET NUMBER 121 I PAGE 131 TITLE l*I Surry Power Station, Unit 2 Io I s I o I o I o I 218 11 1!0FIO 13 TAVE PROTECTION CHANNEL I DECLARED INOPERABLE DUE TO A FAULTY SUMHATOR EVENT DATE 151 LER NUMBER 161 REPORT DATE 171 OTHER FACILITIES INVOLVED 181 H y EAR YEAR ft? SEQUENTIAL NUMBER if? : REVISK>N NUMBER MONTH DAY YEAR FACILITY NAMES DOCKET NUMBERISI 01s1010101 I I 011 ols 9 0 9 lo - o lo 11 - olo o I 2 o Is 9lo o,s,o,o,o, I I THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Chock on* o, mo,* of rhofo!low,ng! 1111 OPERATING MODE IBI N 20.4021b1

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NO SUBMISSION DATE !151 I I I On January 8, 1990 at 2215 hours0.0256 days <br />0.615 hours <br />0.00366 weeks <br />8.428075e-4 months <br /> with Unit 2 at 100%-power, one of the three Reactor Coolant System (RCS) average temperature (Tavg) channel inputs to the reactor protection system was declared inoperable. With this channel inoperable and not in the trip mode, the minimum degree of redundancy required for the high steam flow/low Tavg Safety Injection protection logic specified in T.S.

Table 3.7.2 was not satisfied. The channel was placed in trip at 2230 hours0.0258 days <br />0.619 hours <br />0.00369 weeks <br />8.48515e-4 months <br />. The cause of the event has been attributed to a faulty summator in the Tavg circuit. The faulty summator had been installed earlier that day to replace. the existing summator.

Subsequent testing of the faulty summator could not duplicate the failure. The summator that had been removed earlier was temporarily reinstalled and the channel was satisfactorily tested and returned to service. The summator was subsequently replaced with a third summator modified with the appropriate noise filtration devices.

Repair and testing methods of failed instrumentation components will be enhanced following receipt of additional equipment currently being procured.

NRC Form 31111 19-831

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6-891 APPROVED 0MB NO. 3150-0104 EXPIRES: 4/30/92 LICENSEE _EV. REPORT (LERI ES IN*

ED BURDEN PER RESPONSE TO COMPLY WTH THIS ATION COLLECTION REQUEST: 50.0 HRS. FORWARD TEXT CONTINUATION COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (P-5301, U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO l'HE PAPERWORK REDUCTION PROJECT {3150-01041, OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON. DC 20503.

FACILITY NAME (11 DOCKET NUMBER (21 LER NUMBER (61 PAGE (31 YEAA SEQUENTIAL 1:::::::::: REVISION Surry Power Station, Unit 2 NUMBER ,:::::::-.: NUMBER o Is I o I o I o I z 1s I 1 9 Io oIo I 1 01 0 Oi 2 OF O j3 nxT /If mo,w - ~ ,wqultw, - addltkxw NRC Fomr Ji!il&C '*I (17) 1.0 Description of the Event On January 8, 1990 at 2215 hours0.0256 days <br />0.615 hours <br />0.00366 weeks <br />8.428075e-4 months <br /> with Unit 2 at 100%

power, during the performance of a surveillance test procedure, one of the three Reactor Coolant System (RCS) (EIIS-AB) average temperature (Tavg) channel (Channel I) inputs to the Reactor Protection System (EIIS-JE) was declared inoperable when it was noted to deviate greater than four degrees Fahrenheit from the other two channels. The Tavg protection channel provides an input to the over-temperature delta temperature reactor trip, overpower delta temperature reactor trip and the high steam flow/low Tavg Safety Injection (SI) logics. Technical Specifications (TS) allows six hours to place the bistables for the inoperable channels of over-temperature delta temperature and overpower delta temperature in trip, but does not specify a time limit to perform this action.for the Tavg input to the high steam flow/low Tavg SI channel. Consequently, while the channel was inoperable and not in the trip mode, the minimum degree of redundancy required for the high steam flow/low Tavg SI protection logic specified in T.S.

Table 3.7.2 was not satisfied and T.S. 3.0.1 was in effect.

2.0 Safety Consequences and Implications The over-temperature delta temperature and overpower delta temperature reactor trip logic and the high steam flow/low Tavg safety injection logic require two out of three redundant channel setpoints to be exceeded for actuation. Throughout the event, two channels remained fully operable and capable of providing a reactor trip or safety injection signal if required. In addition, the affected bistables were placed in the trip mode within fifteen minutes thereby providing the T.S. required degree of redundancy.

Therefore, the health and safety of the public were not affected.

3.0 Cause The cause of the event has been attributed to a faulty summator in the Tavg circuit (EIIS-IM). The faulty summator, a rebuilt spare, had been installed earlier NRC Form 388A (6-891

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.-, U.S. NUCLEAR REGULATORY COMMISSION APPROVED 0MB NO. 3150-0104 EXPIRES: 4/30/92 LICENSEE EVE.REPORT (LEA) ES* D BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD TEXT CONTINUATION COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (P-5301. U.S. NUCLEAR REGULATORY COMMISSION. WASHINGTON, DC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT 13150-01041, OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME 111 DOCKET. NUMBER 121 LER NUMBER 161 PAGE (31 Surry Power Station, Unit 2 o 1s Io Io Io I 21 s ,1 9 1o _ o p 11 _ o 1o o 13 oF o 13 TEXT (If,,,,,,. - * - - - . ua addltioMI NFIC Fann .JIIISA'1J 1171 that day per an Engineering Work Request (EWR) to replace the existing summator. The replacement was made to provide more noise filtration in the Tavg circuit to m1n1m1ze spurious alarms. Subsequent testing of the faulty summator could not duplicate the failure.

4.0 Immediate Corrective Action(s)

The channel was declared inoperable, and turbine power was reduced to 99% as a precaution. The affected bistables were placed in trip mode at 2230 hours0.0258 days <br />0.619 hours <br />0.00369 weeks <br />8.48515e-4 months <br />.

s~o Additional Corrective Action(s) ..

The summator that had been removed earlier per the EWR was temporarily reinstalled, and the channel was satisfactorily tested and returned to service. The summator was subsequently replaced with a third summator modified with the appropriate noise filtration devices.

6.0 Action(s) Taken to Prevent Recurrence Presently, failed instrumentation components are repaired and tested on site and stored for later use as replacement components. A review of the repair and testing methods was performed. It was determined that additional "burn in" time following the repair of the components was required to ensure satisfactory performance. Equipment is currently being procured to facilitate performance of this new repair and testing method, and the new method will be implemented upon receipt of the equipment.

7.0 Similar Events Unit 1 LERs: 88-023,87-032, 87-039,89-037 Unit 2 LERs: 88-018, 83-043.

In these events, components in the reactor protection instrumentation system failed decreasing the minimum degree of redundancy required by T.S.

8.0 Manufacturer/Model Number(s)

Hagan Summator Model III.

NRC Form 366A 1~91