ML20206N811
| ML20206N811 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 08/08/1986 |
| From: | Haynes J ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| 1-SR-86-053, 1-SR-86-53, ANPP-00049-JGH, ANPP-49-JGH, NUDOCS 8608260402 | |
| Download: ML20206N811 (3) | |
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Arizona Nuclear Power Project P O. BOX 52034 e PHOENIX, ARIZONA 85072-2034 August 8, 1986 ANPP-00049-JGH/TDS/JEM-96.03 Mr. John B. Martin, Regional Administrator Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Region V 1450 Maria Lane, Suite 210 Walnut Creek, CA 94596-5368 Subject.
Palo Verde Nuclear Generating Station (PVNGS)
Units 1 and 2 Docket No. STN 50-528 (License NPF-41)
Docket No. STN 50-529 (License NPF-51)
Special Report-1-SR-86-053 File: 86-020-404
Dear Mr. Martin:
Attached please find Special Report (1-SR-86-053) prepared and submitted pursuant to Emergency Plan Implementing Proedure-02. This report discusses the NOTIFICATION OF UNUSUAL EVENT that occurred on August 6, 1986.
If you have any questions, please contact T. R. Bradish, Compliance Supervisor at (602)932-5300 Ext. 6936.
Very truly yours, W
. G. Hayn66 ice President Nuclear Production JGH/JEM/dh
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PALO VERDE NUCLEAR GENERATING STATION UNITS 1 AND 2 Notification of Unusual Event of August 6, 1986 Docket Nos. 50-528, 50-529 License Nos. NPF-41, NPF-51 Special Report 1-SR-86-053 At 0423 MST on August 6, 1986, the NRC Operations Center was notified via the Emergency Notification System, of the declaration of a NOTIFICATION OF UNUSUAL EVENT for the Palo Verde Nuclear Generating Station. The NOTIFICATION OF UNUSUAL EVENT was declared pursuant to Emergency Plant Implementing Procedure -02,' which requires the reporting of a reactor trip which is complicated by concurrent or subsequent events or conditions.
Prior to the events which initiated the reactor trips, Unit 1 was in Mode 1 (POWER OPERATION) operating at 100 percent power with generator output at 1308 MWe. Unit 2 was in Mode 1 (POWER OPERATION) at 7 percent power with the generator off-line.
At 0412 MST on August 6, 1986, Startup transformer NAN-X03 tripped resulting in a loss of power to four (4) Unit 1 and five (5) Unit 2 13.8 KV and 4 16 KV buses. Unit 1 loss of power (LOP) affected buses NAN-S05, NAN-S03, NAN-801 and Engineered Safety Features (ESP) bus PBA-S03 Unit 2 LOP busses affected were NAN-S06, NAN-SO4, NAN-S02, NBN-S02, and ESF PBB-SO4 The deenergization of 13 8 KV buses resulted in two (2) Reactor Coolant Pumps (RCP) in each unit being tripped. At 0412 MST, a reactor trip signal was initiated from the Coro Protection Calculator (CPC), flow projected low DNBR, tripping both Units 1 and 2.
The LOP on the ESF buses initiated a Diesel Generator (DG) start in both units on their respective buses. The DGs started and supplied their respective buses as designed. The LOP also affected the Radiation Monitoring System (RMS) which initiated the following ESF functions:
1.
Containment Purge Isolation Actuation Signal (CPIAS).
2.
Control Room Essential Filtration Actuation Signal (CREFAS).
3 Fuel Building Essential Ventilation Actuation Signal (FBEVAS).
FBEVAS was actuated in Unit 2 only, as it was in bypass in Unit 1.
All systems operated satisfactorily in both units.
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At 0414 based upon a conservative evaluation conducted by the shift supervisor, a Notification of Unusual Event (NUE) was declared in response to the degraded electrical conditions, degraded Reactor Coolant System (RCS) flow and the concurrent Unit 2 trip. At 0432, Unit 1 had reenergized the required buses through the startup transformer NAN-X01 and restarted the two RCPs at 0455 The NUE was terminated at 0459 Unit 2 completed reenergization at 0513 AT 0438 and 0530, Unit 1 and Unit 2 reset ESF actuation signals i
respectively. The DGs were unloaded and shut down in Unit 1 at 1154 and in Unit 2 at 0833 The transient did not result in any challenges to fission product barriers or result in the release of radioactive materials. This event continues to be evaluated.
A Licensee Event Report will be submitted within 30 days to further describe this occurrence.
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