IR 05000325/1979042
| ML19344D768 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 03/13/1980 |
| From: | Kellogg P, Ouzts J, Riley B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML19344D765 | List: |
| References | |
| 50-325-79-42, NUDOCS 8004280157 | |
| Download: ML19344D768 (4) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION
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REGION 11 101 MARIETTA ST N.W SUITE 3100
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ATLANTA, GEORGIA 30303
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Report No. 50-325/79-42 Licensee: Carolina Power and Light Company 411 Fayetteville Street Raleigh, North Carolina 27602 Facility Name: Brunswick Docket No. 50-325 License No. DPR-71
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Inspection at Brunswick site near Southport, North Carolina Inspectors:
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3 /i3 (9o J. E. Ouzts '
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Date Signed 0 6 Yla,L -
alisiec B. W. R'
Date Si ned Approved by:
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.Y/f D P.f c. Chief, RONS Branch I$atelSigned SUMMARY Inspection on November 27-29, 1979 Areas Inspected This special, announced inspection involved 25 inspector-hours on site in the area of Unit I reactor trip that occurred on November 20, 1979.
Results
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Of the area inspected, no apparent items of noncompliance or deviations were identified.
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DETAILS
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1.
Persons Contacted Licensee Employees
- A. C. Tollison, Jr., Plant General Manager
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- J. M. Brown, Operations Manager
- S. E. Thorndyke, Operations Supervisor
- George Milliken, Maintenance Manager
- L. V. Wagoner, Engineering Manager G. F. Blackmon, Jr., Shif t Specialist
- R. M. Poulk, NRC Coordinator
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Other Organizations
- D. J. Kemppaimen, General Electric, Brunswick Operations Engineer
- M. L. Crenshaw, Schenectady, New York
- A. E. Coulter, General Eletric, Salem, Virginia
- Attended one or more exit interviews 2.
Exit Interview The inspection scope and findings were summarized on November 28 and 29, 1979, with those persons indicated in Paragraph I above.
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3.
Licensee Action on Previous Inspection Findings
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Not inspected.
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Unresolved Items Unresolved items were not identified during this inspection.
5.
Event Description On November 20, 1979, Unit 1 experienced a reactor trip at 1:35 p.m. from full power while in normal operation. The following conditions existed at the time of the scram:
a.
Unit 2 was out of service.
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The 230 KV transmission line between Delco and Fayetteville was not in service. This line normally carries power to a heavy load center.
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Approximately 40 seconds after the reactor scram, the main generator reverse power relay operated taking the generator off line.
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6.
Subsequent corrective actions taken, initiated, or planned are as follows:
Unit 1 Generator automatic voltage regulator has been better tuned by a.
vendor personnel to optimize its ability to handle marF nal stability i
situations.
Consideration will also be given to similar tuning on
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Unit 2.
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Operations annunciator procedure will be modified to not attempt rebalance at voltage regulator in manual and to limit time in manual
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to that necessary only to reset annunciator.
c.
Carolina Power and Light Company will perform further transmission j
system stability studies and recommendations will follow to minimize
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Brunswick generators experiencing electrical instability.
d.
The vendor, General Electric Co., is considering issuing an information letter to its customers concerning voltage regulator settings v3 system stability.
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Loss of UPS The loss of UPS was particularly reviewed by the inspectors and the personnel from NRC headquarters to determine the cause and significance. The cause of the MPS loss was determined to be a component problem in the sensing circuit that controls the static transfer switch which resulted in a total momentary loss of UPS. Following repairs the UPS equipment was thoroughly retested and proven operable. Special temporary recording and monitoring of certain UPS parameters was discussed. The plant will record El and E2
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bus voltages as AC inputs to UPS, D. C. voltages from two battery sets as D. C. inputs to UPS and the UPS AC output voltage. Control room annunciator actuations and static switching automatic actions will be separately logged for thirty days.
The problems, trouble shooting and retesting of UPS, were closely followed also by J. T. Beard and I. Ahmed of NRC, Bethesda.
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Plant procedures pertaining to UPS operation were carefully reviewed by the
inspectors for adequacy.
l The general expereince history of the UPS at Brunswick was discussed with plant mangement. Except for problems which occurred in very early operation l
at this equipment, experience and availability over the last two years has been very favorable.
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-2-Generator was producing 40 mvars with a power factor close to unity.
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d.
The 230 KV bus voltage at the unit switchyard was at the lower end (230 KV) of the normal operating range (228-235 KV).
The first indications of off normal conditions and operator and equipment actions were as follows:
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" Generator Field Overexcitation" alarm came in a spurious unexpected fashion considering the total event.
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Operator went to annunciator procedure and also verified generator output and field voltage were normal.
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Operator checked transfer volt meter (TVM) and found normal.
h.
Operator shifted from auto to manual control on generator voltage regulator. The overexcitation alarm cleared. Transfer response was slow and the TVM response was not as expected. The terminal voltage of the generator was dropping and the generator began to slip out of synchronization with the transmission system.
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The operator took correct action to adjust voltage of voltage regulatcr
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but generator was too far out of sychronization. The " generator field overexcitation" alarm again came in momentarily.
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Emergency busses El and E2 and RPS busses dropped out on undervoltage relays at approximately 205 KV switchyard voltage.
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Uninterruptable Power Supply (UPS) was lost due to equipment malfunc-tion which isolated the inverter from the UPS bus when voltage to bus E2 was lost. This resulted in an approximate 14 second power loss to Unit I computer causing a loss of event recall which in turn made analysis of total event more difficult.
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Diesel Generators started and restored power to UPS through E2 bus.
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Coast down of the Reactor Protection System (RPS) Mg began and reactor m.
scrammed and main steam Isolation Valves (MSIV) closed.
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Reactor water level decreased, HPCI and RCIC received start signals.
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At the time HPCI was out of service for maintenance. Later at 1:55 p.m.
HPCI was placed in service. RCIC experienced an overspeed trip due to a connector failure in governor feedback circuit. Five to ten minutes later RCIC was manually started successfully. A second CRD pump was started. Reactor vessel water stabilized and started recovery from a low of -40 inches.
Three reactor pressure relief valves cycled open and closed.
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