ML19332C386

LER 89-021-00:on 891022,inadvertent LOCA Initiation Signal Occurred During Monthly Channel Calibr & Functional Test. Caused by Technician Miscommunication.Involved Technicians counseled.W/891121 Ltr

ML19332C386
Person / Time
Site:	Brunswick
Issue date:	11/21/1989
From:	Harness J, Jones T CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
BSEP-89-1048, LER-89-021, LER-89-21, NUDOCS 8911280048
Download: ML19332C386 (5)

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- Cp&L Carolina Power & Light Company Brunswick Nuclear Project i

P. O. Box 10429 Southport, NC 28461-0429 l November 21, 1989 L

FILE: B09-135100 10CFR50.73 SERIAL: BSEP/89-1048 U.S. Nuclear Regulatory Commission i.

ATTN: Docuuent Control Desk Wanhington DC 20555 BRUNSWICK STEAM ELECTRIC PLANT UNIT 1 DOCKET NO. 50-325 1.ICENSE NO. DPR-71 l LICENSEE EVENT REPORT 1-89 021 Gentlemen:

[. In accordance with Title 10. to the Code of Federal Regulations, the enclosed k

Licensee Event Report is submitted. This report fulfills the requirement for a written report within thirty (30) days of a reportable occurrence and is in accordance with the format set forth in NUREG-1022, September 1983.

Very truly yours, i

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! J. L. llarness, General Manager

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..tC,<t,,......,,,,..,..,,,,,,,,,,..,oi Unit I was at 100*4 power and the Emergency Core Cooling Systems were operable in standby readiness. During the performance of the monthly channel calibrat. ion and functional test of RilR-LPCI, ADS, CS, Low Level 3 and liPCI, RCIC Low Level 2 Division 1 Trip Unit Channel Calibration, IMST-RIIR22M, an inadvertent LOCA initiation signal occurred. The event was caused by a technician communicating the wrong terminal leads to another technician performing the meter connections and by the failure of the technicians to identify voltage on the terminal points involved. The involved technicians have been counseled and the vent will be reviewed with appropriate Instrumentation and Cont rol (1&C) personnel, Direction on the proper use of test leade will be provided by the 1&C Electrical subunit managers. A review of appropriate procedures is being conducted to evaluate the feasibility of removing resistance checks from these procedures. The safety significance of this event is minimal in that the systems functioned as designed, no emergency vessel injection occurred and the plant remained stable throughout the event.

Past similar events include LER's 1-87-17, 1-88-01, 2-88-21, and 2-89-03.

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7 Event Inadvertent LOCA initiation signal during MST performance.

Initial Condition 3s Unit I was at 100*. power. The liigh Pressure Coolant Injection System (llPCI)

[ (EIIS/BJ), Reactor Core Isolation Cooling system (RCIC) (EIIR/BN), Automatic Depressurization System (ADS) (EIIS/*), A and B Residual lleat Removal / Low Pressure Cooling Injection system (RIIR/LPCI) (Ells /DO) and the A and B Core Spray system (CS) (EIIS/BM) were operable in standby lineup. The monthly channel calibration and functional test of RilR-LPCI, ADS, CS Low Level 3 and

!!PCI, KCIC Low Level 2 Division 1 Trip Unit Channel Calibration was in progress in accordance with haintenance Surveillance Test (HST) IMST-RilR22M (rev. 5).

Event Description On October 22, 1989, the Instrumentation and Control (ISC) technicians were performing steps 7.27.27.4 through 7.27.27.6 of 1HST-RilR22M. Steps 7.27.27.4 and 7.27.27.5 verify that zero volts AC and DC exist between terminals BB-104 and BB-105 in panel ill'i-P627 indicating that contacts 1_and 2 of 1-E21-K8A are closed. Step 7.27.27.6 verifles that there is zero ohms resistance between the terminal points. Relay E21-K8A closes when analog trip unit B21-LTS-N031C-4 transmits a Low Ltwel 3 signal. The closing of E21-K8A energizes relays E21-K10A, K100, and K11 A which result.s in the starting of the A CS pump, alignment of A CS for injection (if a reactor low pressure permissive is satisfied), isolation of Instrument Air (Ells /LD) from the drywell, starting of the four Diesel Generators (Ells /EK), tripping of drywell cooling fans, closure of the Reactor Fullding Closed Cooling Water (RBCCW) lleat Exchanger Isolation Yalve (1-SW-V106) (EIIS/*/11X/ISV) and other LOCA logic signals. At approximately

.1015, the techi.ician reading the procedure and observing the meter saw infinite ohms instead of zero. The technician holding the test leads on the l . terminals removed them, pushed back the rubber boots on the alligator clips to ensure contact and reapplied the 1 cads to the same terminals. When reapplying L the leads, the technicians heard relays change state in the involved cabinet and immediately withdrew the 1 cads. The action of the relays resulted in an .

inadvertent h0CA initiation signal when the leads were placed on the terminals. The technicians noted that. they had placed the leads on terminals BB-104 and BB-103 instead of BB-104 and BB-105 as required by the MST. They  !

immediately went to the Control Room and informed Operations that they had caused the LOCA initiation signal.

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As a result of the LOCA initiation signal, the 1A Core Spray pump started, all four Diesel Generators started, four drywell chiller fans tripped, instrument air to the drywell isolated, and 1-SW-V106 throttled closed to the 20'. open position as designed. After verifying that a valid initiation signal did not exist, Operations secured the 1A CS pump. The affected systems were placed back in their normal lineup at approximately 1030 after the plant was stabilized. The MST was completed without further incident.

Event _ Investigation ,

3 The circuitry associated with steps 7.27.27.4 through 7.27.27.6 of IMST-RHR22M is the Division 1. CS Low Level 3 (LL3) LOCA logic. Given a LL3, signal the involved logic energizes relays E21-K10A, K100, and KilA resulting in the actions observed by the operators. In accordence with its Division Il circu~itry, the CS B pump did not initiate because m)v Division 1 circuitry was involved.

During this event the technician reading the procedure and observing the volt / ohmmeter (VOM) stated the wrong terminals to the technician performing the meter connections (i.e.: BB-103 and BB-104 instead of BB-104 and BB 105).

Approximately 15 minutes prior to this event, terminals BB 103 and BB-104 had been used to verify closed contacts associated with Relay E21-K7A via steps 7.4.27.4 through 7.4.27.6. It is believed that a mindset resulting from the recent use of these contacts combined with inattention to detail resulted in the first technician improperly stating the terminal numbers to the second technician.

IMST-RHR22M utilizes a voltage and then a resistance check to verify that relay contacts are closed when required by the procedure. In this case, a poor electrical connection resulted in the observed zero volts and infinite c'ams on the meter. The involved technicians did not reverify zero volts after pushing back the rubber boots on the alligator clips. When the leads were reapplied to the terminals, a solid electrical connection wcs achieved through the low resistance circuitry of the ohmmeter and the closed contacts of E21-K8A resulting in the LOCA initiation. The proper use of test leads is a skill related task that is covered in the I&C/ Electrical training quslification program. In this case, probe type leads with sharp points would have provided a better electrical connection than the alligator clips for the momentary voltage and resistance checks required by the MST.

Root Cause This event had two causes. One was the error of the technician in j communicating the wrong terminal leads and the other was the f ailure of the l

technicians to identify voltage on the terminal points involved.

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Corrective Actions ,

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1. The technicians involved have been counseled.

2. This event will be reviewed with appropriate Instrumentation and Control personnel by November 30, 1989.

3. Direction will be provided by the 16C/Electsical Subunit managers as to the proper use of test 1cada for momenta y checks during maintenance evolutions by Ncvember 30, 1989. .

4. A review of the procedures involved to test this logic, 152MST-Ri!R22M and 23M revealed that the method for verifying closed contacts is not the  :

same between procedures. Both MST RilR22M procedures use the voltage and [

resistance check methods to verify closed contacts whereas the MST-RilR23tf procedures only use a voltage check. The removal of the resistance check would greatly reduce the consequences of an error s.uch as occurred in

.this event. An investigation will be done to determine the feasibility and technical acceptability of removing resistance checks from these '

procedures by January 1'390.

5. This event will be reviewed by Maintenance Real-Time Training by January 15, 1990.

Event Assessment The safecy significance of this event. is considered minimal in that the systems functioned as designed, no emergency injection to the reactor vessel occurred and the plant remained stable throughcut the event.

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