PNO-IV-98-066, on 981225,large Influx of Fish (Shad) Affected Unit 1 Intake Structure,Resulting in Degraded Available Circulating Water Pump Suction Pressure.Shade Runs Have Historically Occurred as Result of Cyclic Changes
| ML20198H950 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 12/29/1998 |
| From: | David Loveless, Marchall C NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| References | |
| PNO-IV-98-066, PNO-IV-98-66, NUDOCS 9812300061 | |
| Download: ML20198H950 (2) | |
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December 29,1998 4
as PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-IV-98-066 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by Region IV staff in Arlington, Texas on this date.
Facility Licensee Emeraency Classification Entergy. Operations, Inc.
Notification of Unusual Event Arkansas Nuclear 1' Alert
- Russelville, Arkansas Site Area Emergency Dockets
- 50-313 General Emergency X Not Applicable
Subject:
PLANT SHUTDOWN FOR GREATER THAN 72 HOURS FOLLOWING REACTOR TRIP On December 25,1998, a large influx of fish (shad) affected the Unit 1 intake structure, resulting in degraded available circulating water pump suction pressure. Operators began to reduce reactor power at 8:49 a.m. (CST) and inserted a manual trip 2 minutes later from 75 percent i
power. Following the trip, the Train B startup feedwater control valve failed at approximately 50 percent open. Operators isolated the line and used the emergency feedwater system to maintain water level in Steam Generator B. Plant staff repaired the valve prior to restart. Additionally, during an inspection of the reactor coolant system, operators identified a leaking valve in the cooling water line to Reactor Coolant Pump D and a small reactor coolant system leak on an incore neutron instrument housing flange. Technicians torqued the flange bolts to isolate the incore instrumentation leak and replaced the leaking cooling water valve.
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Shad runs have historically occurred as a result of cyclic changes in daily temperatures. As a
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result, licensee management maintained the reactor in Mode 3 for 2 additional days to determine that the shad peaks had abated prior to retuming the unit to power. In addition, i
i maintenance personnel modified the circulating water screens to improve the system's effectiveness in removing shad from the circulating water pump suction.
On December 27,1998, operators made the Unit 1 reactor critical at 10:30 p.m. and connected the main generator to the grid at 7:15 a.m. on December 28. They again manually tripped the reactor., however, from 7 percent power 8:35 a.m. on December 28 following another large shad influx. All major plant equipment functioned as designed. Licensee management stated that the unit would remain shut down for an unknown period of time to develop coping strategies for the unusually large shad runs and to consider designing and installation of additional intake screen modifications. As a result of observing startup activities, the resident inspectors observed the second reactor trip from the main control room.
Due to the use of a cooling tower, the shad influx did not affect Unit 2 during either Unit 1
. transient. Unit 2 remains operating at 84 percent power, coasting down to the end of the current operating cycle.
i The state of Arkansas will be informed.
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9812300061 981229 L
PDR I8dE 63 4
V O I vo o
Region IV received notification of this occurrence by telephone from the resident inspectors.
Region IV has informed the EDO, NRR, and PA.
This information has been discussed with the licensee and is current as of 4 p.m. on December
, 28,1,998.
Contact:
Charles Marschall David Loveless (817)860-8185 (817)860-8161
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