United States Nuclear Regulatory Commission - Protecting People and the Environment

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REGION I  MORNING REPORT     PAGE  2                    FEBRUARY  8, 1995

Licensee/Facility:                     Notification:

Niagara Mohawk Power Corp.             MR Number: 1-95-0020
Nine Mile Point 1                      Date: 02/08/95
Lycoming,New York                      SRI PC                             
Dockets: 50-220
BWR/GE-2                              

Subject: PLANT SHUTDOWN DUE TO PROBLEMS WITH AGASTAT RELAYS              
                                                                         
Reportable Event Number: N/A

Discussion:

At 8:30 p.m., on February 7, 1995, Nine Mile Unit 1 commenced a normal   
plant shutdown after identifying that three (of eight) Agastat relays in 
the power supplies for the analog trip subsystem (ATS) of the reactor    
protection system (RPS) were not functioning.  The specific relays       
provide annunciation on power supply failure.  Several weeks earlier     
during scheduled fuse replacement, it was noted that the ATS power       
available indicating light in the control room did not extinguish when   
expected. A work order was initiated to repair the system; the failed    
relays were found yesterday during troubleshooting activities.           
                                                                         
ATS is the portion of RPS that includes the relays associated with the   
various parameters that feed the protective circuitry to initiate        
protective actions, such as reactor scram or core spray actuation. The   
three relays that failed were 24 VDC Agastat relays, model FGPBC750. The 
relays are normally energized, and deenergize to trip.  The ATS cabinets 
were installed circa 1980, and most of the relays are original equipment.
Investigation continues to determine whether other 24 VDC relays which   
supply RPS trip, emergency core cooling system initiation, and           
containment isolation signals, or the other Agastat 110 VAC and 125 VDC  
relays in the ATS cabinets are also affected. Preliminarily, NMPC feels  
that aging coupled with the temperature inside the cabinets caused the   
failures.                                                                
                                                                         
NMPC did not declare any equipment inoperable, but took what they        
considered prudent action to comply with the most restrictive limiting   
condition for operation (LCO) on potentially affected emergency core     
cooling system components. This required initiation of a shutdown within 
one hour and cold shutdown within the next ten hours. As of the time of  
this report, the reactor coolant system is at 178 degrees F and the      
shutdown cooling system is in operation.  The plant was scheduled to     
begin a refueling outage on February 11, 1995.                           

Regional Action:

The resident inspectors will continue to follow this issue.              

Contact:  Lawrence Doerflein         (610)337-5378
          Barry Norris               (315)342-4041

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