Headquarters Daily Report

                         OCTOBER 03, 1997

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                    REPORT             NEGATIVE            NO INPUT
                    ATTACHED           INPUT RECEIVED      RECEIVED

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PRIORITY ATTENTION REQUIRED  MORNING REPORT - REGION I  OCTOBER  3, 1997

Licensee/Facility:                     Notification:

Public Service Electric & Gas Co.      MR Number: 1-97-0054
Salem 2                                Date: 10/03/97
Hancocks Bridge,New Jersey                                                
Dockets: 50-311
PWR/W-4-LP                            

Subject: REACTOR TRIP DUE TO DATA ACQUISITION SYSTEM INTERACTION         
Reportable Event Number: 33019                         

Discussion:

At 7:14 a.m., October 2, operators manually tripped the Salem Unit 2     
reactor from full power due to a trip of both steam generator feedwater  
pumps.  Event Notification 33019 provides the details of the reactor     
trip.                                                                    
                                                                         
The licensee has identified the cause of the trip as an undesirable      
interaction between data acquisition system (DAS) equipment and plant    
instrumentation.  The DAS had been previously installed to monitor       
performance of the advanced digital feedwater control system (ADFCS)     
throughout the licensee's integrated test program.  Just prior to the    
trip, a DAS power supply unexpectedly failed which caused the sensed     
steam generator feedwater pump (SGFP) discharge pressure to drop by      
approximately 100 psi.  Actual SGFP discharge pressure remained normal.  
The sensed low pressure caused the ADFCS to attempt to restore pressure  
by raising SGFP speed which caused the low suction pressure condition    
that generated the SGFP trip signal.  The licensee is planning to        
disconnect the DAS prior to plant startup.                               
                                                                         
Regarding the test equipment interaction, Information Notice (IN) 95-13, 
Potential for Data Collection Equipment to affect Protection System      
Performance, describes the likely interaction mechanisms for this type of
plant behavior.  The IN notes that the mere deenergization of a DAS can  
cause a rapid change in impedance that can have a direct and undesirable 
effect on plant instrumentation.  This provides a plausible explanation  
for the feedwater perturbation.  The licensee is continuing to           
investigate this matter.                                                 

Regional Action:

The Resident Inspectors will continue their review of the licenseeþs     
corrective actions.                                                      

Contact:  G. Scott Barber            (610)337-5232
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