ML20044A552
| ML20044A552 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 06/20/1990 |
| From: | Tucker H DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9006290200 | |
| Download: ML20044A552 (3) | |
Text
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l Duke hwer Conutq flu U h k' l'a tha 3314s Ike l'enutent ChurInte, N C 28.'42 NucIrar l*rodut tion (IN)373 4DI l
DUNC POWER June 20, 1990 U. S. Nuclear l'ogu3atory Counission Attn i)ocument Cont rol Donik Washington, D.C.
20555
Subject:
Catawba Nuclear Stat.lon, Urit 2 Docket No. 50-414 Special Hoport Contlement Pursuant to Technical Specifications 6.9.2 and 4.8.1.1.3, pleano find at tached a Special Report concerning Unit 2 Diosol Conorators 2A and 211 invalid failures on May 21, 1990, and Juno 12, 1990, respectively.
Very truly yours.
hi N r-s
- 11. 11. Tucko r Milli 2/lca Attachmont xc Mr. S. D. Ebnoter i
Regional Administrator, R11 U. S. Nuclour Regulatory Commission 101 Mariottc Stroot NW,Suito 2000 Atlanta, Georgia 30323 l
Dr. K. Jabbour i
Office of Nuclear Regulatory Regulation U. S. Nuclear Regulatory Counission Ono Whito Flint North j
Mail Stop 1 4112 5 Washington, D.C.
20555 Mr. W. T. Orders NRC Resident inspector Catawba Nuclear Station j
i 9006290200 900620 gff b 1
- F'llR : ADOCK 03000414 r
S PDC i
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m SPECIAL REPORT CATAWBA NUCLEAR STATION DIESEL GENERATOR 2A 7 2B INVALID FAILURE DURING OPERABILITY TESTING OF ENGINE PROBLDi INVESTIGATION REPORT NO. 2-C90-0177 & 2-C90-0195 INCIDENT INVESTIGATION REPORT NO. C90-048-2 & C90 053-2 i
An invalid failure (Start //605) of Diesel Generator (D/G) 2A occurred on May 21, 1990, at 0845 hours0.00978 days <br />0.235 hours <br />0.0014 weeks <br />3.215225e-4 months <br />. The failure occurred on the closing of the D/G breaker when synchronizing to the energized bus during the monthly operability performance test, PT/2/A/4350/02A. Thoro have boon zero valid failures in the past 20 valid starts and two valid failures in the past 100 valid starts for D/G 2A.
After discussions with the operator involved in this evolution there was a strong reason to believe the " voltage control" raiso pushbutton was depressed instead of the " speed increaso" pushbutton. This caused t.he power factor to be reduced and caused a reverso power trip.
The operator also stated that line voltage may have been higher than diesel output voltage which also would have tripped the D/G on reverse power.
Since this trip was duo to either an operator error or an equipment malfunction that is not needed in an omorgency start (the reverse power trip is not functional in an emergency start. because the D/G la designed to be loaded onto a dead bus),
this start attempt was classiflod as an invalid failure per Regulatory Guido 1.108. The operator subsequently successfully closed the output breaker and loaded the D/G.
Following this invalid failure, work requests 46437 OPS and 46438 OPS vere written. Work request 45437 OPS verified the calibration of the volt motors to ensure the accuracy of the meter indication the operator was observing.
Work request 45438 OPS will check the reverso power rolay for proper operation during the Unit 2 refueling outage.
Based on the outcomo of the first work request and the discussion with the operator, it was initially concluded that this trip of the breaker on 5/21/90 was caused by operator error.
This was the second incident of an invalid failuro in the past two months due to a reverse power relay actuation.
A special report was sont in on 5/17/90 for a similar situation for 2B Diosc1 Generator which occurred on 4/18/90. The first incident on 4/18/90, was attributed to an isolated case of individual operator error. The basis for this determination was no equipment malfunction could be identified and the frequent opportunities for the operators to preform the D/G paralleling evolution with no previous incidences of reversed power trips due to operator error.
Since this was the second occurrence of this type incident, it became apparent the root cause may not have been an isolated individual operator error. The previous corrective actions at that time included discussing the evolution / procedure with the operator involved. Because of the operator training deficiency implied by the second event, additional training on this evolution will be provided to all operators during operator requalification training.
In addition, this event has been discussed during Shift Supervisors Staff mootings.
e e
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SPECIAL REPORT CATAWBA NUCLEAR STATION DIESEL GENERATOR 2A 7 2B INVALID FAILURE DURING OPERABIh!TY TESTING OF ENGINE PROBLIM INVESTIGATION REPORT No. 2-C90-0177 & 2-C90-0195 INCIDENT INVESTIGATION REPORT NO. C90-048-2 & C90-053 2 Since the second Invalid Failure on 5/21/90, the station has had an additional reverso power trip, on D/G 28.
This invalid failure occurred following the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> survol11anco run on 6/12/90 (Starts 584 and 585).
This situation was slightly different in that the D/G had just completed its 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> run and was being used to maintain the loads on 2ETB switch gear while its source of power was being swapped from the normal supply of 2ATD to its alternato supply of SATB.
When tho Diosol Generator was parallolod to 2ETB at the beginning of the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> run, no problem was encountered with the breaker. Thoro has boon ono valid f ailuro in the past 20 valid start.s and three valid failures in the past 100 valid starts for D/G 2B.
Operators and Station management. woro very sensitivo to the previous Invalid Failures t. hat. had occurred due to operator errors. Thoroforo, prior to closing the breaker to SATB, two non-licensed operators along with the Unit Supervisor, vortfled proper indicaticn at the local control panol in the Diosol Generator Room. The Operator at t he Controls (OATC) also verify the indication prior to closing the breaker in the control room. When the breaker to the alternato source was closed the D/G output breaker tripped open on reverso power.
Power was not lost to equipment energized f rom the ossential bus.
It was verified by multiplo observors that no operator error was involved in this occurrenco.
Prior to shut. ting the D/G down the Diosol Conorator output breaker was reclosed twice to verify it would closo.
Following this invalid failure, additional work request 46377 OPS was writton to verify propor operation of the relay onco again on 2B D/G.
This additional event indicates the possibility of a root cause not.
associated with operator error.
A special t.csting program is being developed to furt. hor investigato and bot. tor ovaluato the proper functioning of the components involved in this circuitry while Unit 2 is in its refueling outago. This report will be updated after D/G 2A and 2B are returned to service from planned maintenanco during the present outage to provide the details and Iindings of the testing program.
The D/G 2A and 2B woro both availablo during thoso periods as the reverse power relay trip and associated synchronizing circuitry are being bypasson on an omorgency start. The bus is shed and t. hon the D/G breaker is closed and the essential loads are put on to the bus which la supplied solely irom the D/G at. that timo.
Thorofore the operability of the D/G's are not affected by this circuitry.
The test surveillanco interval is onco por thirty-ono days for both Dional Generators which is in compliance with Technical Specification 4.8.1.1.2 table 4.8-1.
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