ML20215J322
| ML20215J322 | |
| Person / Time | |
|---|---|
| Site: | Mcguire |
| Issue date: | 04/29/1987 |
| From: | Tucker H DUKE POWER CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NUDOCS 8705070364 | |
| Download: ML20215J322 (5) | |
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Dmm POWER GOMPANY P.O. BOX 33180 CHARLOTrE. N.C. 28949 HALH. TUCKER Tetzenons.
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afU05. RAS PapeccTleet April 29, 1987 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C.
20555
Subject:
McGuire Nuclear Station Docket No. 50-370 Diesel Generator Failure Special Report Gentlemen:
Please find attached a Diesel Generator failure report submitted pursuant to Technical Specification (T.S.) 6.9.2 as specified in T.S. 4.8.1.1.
This report concerns an invalid failure of Diesel Generator 2A due to management failure to give adequate instructions.
This event is considered to be of no significance with respect to the health and -
safety of the public.
Very truly yours, d4 k. '
Hal B. Tucker SEL/42/jgm Attachment xc:
Dr. J. Nelson Grace American Nuclear Insurers Regional Administrator, Region II c/o Dottie Sherman, ANI Library U.S. Nuclear Regulatory Commission The Exchange, Suite 245 101 Marietta St., NW, Suite 2900 270 Farmington Avenue Atlanta, GA 30323 Farmington, C'"
06032 Mr. W.T. Orders ifr. Darl Hood NRC Resident Inspector U.S. Nuclear Regulatory Commission McGuire Nuclear Station Office of Nuclear Reactor Regulation Washington, D.C.
20555 INPO Records Center M&M Nuclear Consultants Suite 1500 1221 Avenue of the Americas 1100 Circle 75 Parkway New York, NY 10020 j g Atlanta, Georgia 30339
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9705070364 870429 I
l PDR ADOCK 05000370 t
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Invalid Failure of. Diesel Generator 2B Due to a Management Failure to Give Adequate Instructions INTRODUCTION On March 30,1987, at 1129, during the performance of a routine diesel
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generator' operability test, Diesel Generator 2B. (D/G 2B) experienced an invalid failure following a normal start. Periodic Maintenance (PM) was being performed on a pressure switch which trips the diesel when in the' manual-start /run mode if the cooling water pressure is below the setpoint. Due to a breakdown in communications, the Operators were unaware that the pressure switch was isolated and removed when they started D/G 23.
D/G 2B tripped on a low cooling water pressure trip signal. This trip. circuit is bypassed during an emergency start; therefore, this trip constitutes an invalid failure. The pressure switch was replaced and unisolated. A successful diesel generator operability test was then completed by 1202.
Unit 2 was in Mode 1, Power Operation, at 100% power, at the time of this incident.
This incident has been attributed to a management deficiency because management failed to adequately instruct Operations personnel on the conditions for operation of the D/G.
BACKGROUND-Each unit'at McGuire Nuclear Station (MNS) has two independent Diesel Generators (D/Gs). As part of the' Essential Power. System,'they provide standby AC power to-the equipment required to safely shut down the reactor in the event of the loss of normal power. The D/Gs also supply' power to the safeguard equipment as required during a major accident coincident with a loss of normal power (blackout).
Esch D/G has two start /run circuits: a manual circuit for routine operation and an emergency start /run circuit actuated by the Safeguards Systems. For i
l added protection during routine operation, there are several trip circuits connected in. series with the manual start /run circuits to shut the diesel down. Many of these trips are completely bypassed during a start up initiated
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by the Safeguards Systems.
j Diesel Generator Cooling Water System (KD) pressure is measured by KD Pressure Switch 5051 (KDPS 5051), which has contacts in series with the diesel start /run circuits. During a manual start, relay 2TRA provides a bypass around KDPS-5051 for 20 seconds. After the 20 second delay the bypass I
contacts open, and if KDPS 5051 is not closed (indicating inadequate cooling i
-water pressure), the start /run circuits for the diesel automatically open and the diesel shuts down. During an emergency start, another non-timed relay bypasses KDPS 5051.
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l DESCRIPTION OF EVENT t
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Maintenance personnel began a series of PMs on D/G 2B on March 30,1987, at approximately 0830. 'By approximately 0900, they were preparing to calibrate KDPS 5051, and contacted the Operations Shift Supervisor to advise that the
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manual start circuits for the diesel would be inoperable while they were
' working on KDPS 5051 and that the work would take approximately one hour.
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Maintenance personnel, hereafter called the KDPS Crew, were cleared to begin
. work.
Work on another PM was also in progress, on the Voltage Regulator, ~ but by a Ldifferent Maintenance crew, hereafter called the VR Crew. This PM was of a nature that would disable the D/G 2B emergency start /run circuit and all log entries had been made at 0600 to document this and declare D/G 2B inoperable in preparation for.the FM work. The work on the Voltage Regulator had been finished by approximately 1030.'
In consonance with the Integrated Scheduling program, the post maintenance retest for the Voltage Regulator work and the periodic operability surveillance test were to be done at the same time so that only one diesel start would be required instead of two.
The VR Crew completed their work and contacted the Control Room at approximately 1030 to arrange for the post maintenance retest diesel start.
Control Room personnel contacted the Operations Periodic Test Group and asked to have the operability test run. Two operators responded; Operator A went to the Control Room and Operator B went to the D/G 2B Room to conduct the test.
An Operations Engineer who had responsibility for the D/Gs also went to the 4
D/G 2B Room to render whatever assistance might be required. The two Opera-1 tors were unaware of either maintenance activity at this point, believing they were simply running the routine operability test.
The Operations Shift Supervisor and the Operations Engineer were both aware of the maintenance
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activities.
j Between approximately 1000 and 1030, the KDPS Crew discovered a frayed wire on j
the pressure switch (KDPS 5051), isolated the instrument line, removed the pressure switch, and took it to the Maintenance shop for further evaluation.
They were not in the D/G 2B room when Operator B and the Operations Engineer arrived to conduct the operability test.
I-Shortly af ter 1100, Operator. B in the D/G 2B Room called Operator A in the Control Room for confirmation that it was alright to start the diesel. The r
l Operations Shift Supervisor agreed, provided that Maintenance personnel were finished with their work. He was referring to the KDPS Crew but did not specifically identify them. This information was relayed to Operator B in the D/G 2B Room. Operator B asked the Operations Engineer to check with the Maintenance crew across the room to see if they were finished.
It was the VR Crew, which was waiting on the diesel start for the retest. They indicated they were through and the Operations Engineer relayed this information to Operator B.
l At 1129, D/G 2B was manually started (start No. 503, Invalid failure), and 20 seconds later it tripped on a Low Cooling Water Pressure signal.
The cause was recognized almost immediately by the Operations Shift Supervisor and was confirmed by Operator B in the D/G 2B Room. The KDPS Crew was contacted; they
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completed the PM, reinstalled the pressure switch, and unisolated the instru-l ment lines. Then at approximately 1202, D/G 2B was again started (start No.
504 Valid success) and the operability test was successfully completed.
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CONCLUSION This incident resulted in an invalid failure of D/G 2B.
Unit 2 D/Gs still have six valid failures in the last one hundred valid starts. The test frequency at the time of this failure was every three days and thic frequency did not change as a result of this failure.
The Operations Shift Supervisor assumed that everyone involved was aware of both maintenance activities and that one activity (the Voltage Regulator PM) was obviously complete because the crew had called in to have the diesel started for the retest. Therefore, :b2 his mind, the condition for running the diesel generator was obviously related to the other maintenance activity (KDPS 5051.PM). Had he pursued the evaluation of the second maintenance activity a little further, he would have discovered that it had not been completed.
The Operations Engineer in the D/G 2B Room did not see the KDPS Crew and assumed they were finished. When asked to check to see if they were finished, it seemed logical to him that the reference was to the VR Crew who were present in the room.
Had he checked further into the pressure switch work, he probably would have discovered it was not complete.
This incident has been attributed to management deficiency because management failed to ensure that instructions were clear and concise on the conditions necessary for the operation of the D/G.
An Operating Schedule is published on a weekly basis which shown all scheduled PM work and operation of all four D/Gs. Through an oversight the PM on the KD pressure switches was not shown on the current schedule, but the work had been assigned to a M intenance crew anyway. The schedule is only updated once a a
week; therefore, add on work would not always be shown until the next update.
A copy of the Operating Schedule was available in the Control Room.
A review of past McGuire reports indicates there have been several where communications errors have resulted in reportable events. Most are attributed to personnel errors or deficiencies in administration. None of the corrective actions would have prevented this incident because they relate to the specifics of the' individual incidents only.
This incident is not Nuclear Plant Reliability Data System (NPRDS) reportable.
ADDITIONAL CORRECTIVE ACTIONS None
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SAFETY ANALYSIS In this incident, D/G 2B tripped on a Low Cooling Water Pressure signal. This trip function is completely bypassed on a D/G actuation by the Safeguards Systems. The Cooling Water system was fully functional, but the instrument line had been isolated and the pressure switch could not function.. There was
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no impact on plant safety, no Technical Specifications were violated or action statements entered, and no violation of the Safety Analysis in the Final Safety Analysis Report occurred as a result of this incident.
There were no personnel injuries, personnel overexposures, or releases of radioactive material as a result of this incident.
The health and safety.of the public were not affected by this incident.
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