ML20127L471

Provides NRC Periodic Performance Repts Related to Zion Unit 1 Eagle 21 Process Protection Sys

ML20127L471
Person / Time
Site:	Zion File:ZionSolutions icon.png
Issue date:	01/21/1993
From:	Stimac S COMMONWEALTH EDISON CO.
To:	Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
References
NUDOCS 9301270167
Download: ML20127L471 (5)

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_ ) 1400 Opus Placs s Downers Grove, lulnois 60515 January 21,1993 Dr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear R ulatory Commission Washinuton, D. 20555 Attention: Document Control Desk

Subject:

Zion Station Unit 1 Eegle 21 Process Protection S tem Penodic System Performance eport NBC_DocheLNoJ0 295

References:

(a) April 10,1992 letter from S.F. Stimac to T.E. Murley, (b) September 23,1992 letter from S.F. Stimac to T.E. Murley.

Dear Dr. Murley:

Commonwealth Edison Company committed via reference (a) to provide NRC periodic performance reports related to the Zion Unit i Eagle 21 Process Protection System. Pursuant to this commitment, please find enclosed one copy of " Zion Station Unit 1 Eagle 21 System Performance Report," dated January 21,1993. This is the second periodic report for Unit 1. The first periodic report was submitted via reference (b). As described in reference (a), additional performance reports will be submitted periodically throughout the first Unit 1 operating cycle with Eagle 21.

Please direct any questions you may have to this office.

Respectfully,

<. ~ C i

~ Stephen F. St mac Nuclear Licensing Administrator Enclosure cc: A. Bert Davis, Regional Administrator - Rlli C.Y. Shirakl, Project Manager - NRR J.D. Smith, Senior Resident inspector - Zion Office of Nuclear Facility Safety -lDNS

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i ZION STATION UNIT 1 ,

EAGLE 21 SYSTEM PERFORMANCE REPORT JANUARY 21,1993  ;

This performance report covers the period from September 15,1992 to January 15,1993. During this period the following events relative to Unit 1 Eagle 21 '

performance occurred.

On August 25,1992*, Unit 1 was increasing power level when Loop A Overpower Delta T Turbine Runback alarm was received. This occurred at approximately 96% power. The unit operators backed down in power to approximately 93.5% and held steady. In parallel with this it was observed that the Delta T/Tavg Indicators were fluctuating on the control board. As a result, Unit I was hold below approximately 96% and an investigation began. i Action Taken: As a result of troubleshooting and discussions with Westinghouse, it was determined that a 2 second lag function off of the RTD's was missing irom the Eagle 21 software design.

Westinghouse was asked to reevaluate the Delta T/Tavg design with the 2 second lag function included. Setpoint changes were initiated to include the 2 second lag into the Eagle 21 software. Subsequent testing was satisf actorily performed. As a result of the setpoint changes, Unit 1 is now capable of operating at 100% power.

Cause: The causel factor for this event was inadequate design configuration and analysis.

Historical files show that Sostmen Narrow Range RTD's were replaced with Rosemount RTD's. The Rosemount RTD's had a much faster response time than the Sostman RTD's.

Because of the faster response time, Westinghouse recommended using a special summator in the previous analog system to calculate Tavg with a built in 2 second lag capability. The 2 second lag filtered out the temperature fluctuations the fast acting RTD's generated. The 2 second lag function within the special summator was not identified during the Eagle 21 modification process, due to the f act that lead / lag functions are usually performed by Hagan modules specifically designed to perform a lead / lag funct!on. This special summator, with bu41 in lag, was an exception.

Additionally, the Instrument Data Sheets describing the special summator did not specify a time constant. The only documentation of the lag function was in the Instrument Maintenance procedure.

Preliminary investigation of this event was in progress at the time that the previous report was prepared.

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, ~ Coune (cont'd): As a result of the omission of the 2 second lag, the tem aerature fluctuations Generated by the RTD's were evic ont on the control room Indicators as well as the analog outputs from the respective Tavg channels. The configuration management controls currently in place ensure that design changos are accurately reflected in design documents. As a result, the 2 second lag has boon incorporated into the unit 2 design.

On September 25,1992, a Eagle Analog Input (EAI) buard in rack 11 was found out of calibration during a channel functional tost for a steam generator prossure loop. The EAl board was unable to be calibrated back into tolorance.

Action Taken: The EAl board was replaced and subsequent testing was satistactorily performed.

Cause; The cause of the board failure is presently unknown. The board was sont to Westinghouse for failure analysis and warranty repair.

Failure analysis results will be provided in the next periodic performance report after the results are available.

On December 5,1992, Rack 12 began producing PROTECTION SET lll TROUBLE" and " PROTECTION CHANNEL TROUBLE" alarms.

Troubleshooting of Rack 12 then began. l Action Takon: As a result of troubleshooting, it was determined that the Rack 12 primary 15 volt power supply had failed. The Loop Calcuiation Processor / Primary Power Supply Drawer was i replaced and subsequent testing was successfully performed, i l

Causo: The cause of the power supply failure is presently unknown.

The ower supply was sent to Westinghouse for failure anal sls and warranty repair. Failure analysis will be prov ed in the next parlodic performance report after the results are available.

On December 16,1992, Unit 1 was in Mode 1 (Power Operations). The  ;

instrument Maintenanco Departmont was perform!ng channel functional teste on steam generator feedwater flow and steam generator steam flow channels in Rack 3. During the performance of the channel functional tosts, test points are calibrated using the High Precision Digital to Analog Converters (HPDACs). Test points on the front of the test panel are used for this purpose.

During this stage of the functional test, no values could be obtained from test oolnts 9,10,11, and 12. As a result of this observation, testing was halted on 1he affected loops and troubleshooting began.

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o. Action Taken: As a result of troubleshooting,it was discovered that the #2 i HPDAC in Rack 3 was defective. The board was replaced and subsequent testing was successfully performed. i Cause: The cause of the board failure is presently unknown. The board was sent back to Westinghouse for failure analysis and warranty repair. Fallure analysis results will be provided in 1 the next periodic performance report after the results are  ;

available. l On January 3,1993 Rack 10 began producing

• PROTECTION SET ll TROUBLE and " PROTECTION CHANNEL TROUBLE" alarms.

Troubleshooting of Rack 10 then began. l Action Taken: As a result of troubleshooting, it was determined that the i Rack 10 primary 15 volt power supply had failed. The Loop 'l Calculation Processor / Primary Power Supply Drawer was  ;

replaced and subsequent testing was successfully performed.

Cause: The cause of the power supply failure is presently unknown.

The ower supply was sent to Westinghouse for failure anal sis and warranty repair. Failure analysis will be prov ed in the next periodic performance report after the results are available.

As discussed in the first Ea board failures for which no "gleanalysis allure 21 system performance had been report, there were three obtained from Westinghouse prior to submitting the report, Failure analysis results have since been received and are provided below:

when the Unit On August o perator noticed 14,1992, that the Unit Loo) 1 C was Tavg in Mode 2channe instrument (Hot Standby)l was spiking high.

However, the channel was st 11 within the channel check acceptance criteria with respect to the other Tavg channels. The Tavg channel is processed by Eagle 21. As a result of this observation, the MMI was connected to rack 10 and troubleshooting began.

Action Taken: As a result of troubleshooting, it was determined that the associated Eagle Analog Output board in rack 10 was defective. The board was re was successfully performed.placed and subsequent testing Cause: The board was sent to Westinghouse for failure analysis and warranty repair. The results of the analysis found that the spiking output was due to a defective precision isolation amplifier. A possible cause of the defective isolation amplifier is random component failure.

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Durin a Commonw: ith Edison Instell tion cnd siert up t: sting, en EPT bo rd in

. rack 11 produced a " PROTECTION CHANNEL TROUBLE" alarm.

On July 13,1992, during Eagle 21 operational performance, an XHT board in rack 10 began generating spurious " PROT ECTION CHANNEL TROUBLE" Action Taken: The boards were replaced. Subsequent testing was satisfactorily performed.

Cause: The boards were sent to Westinghouse for failure analysis and warranty repair. After evaluation, tne failures could not be duplicated. A possible cause of these occurrences is loose connections. These could have occurred durin y rack installation at the site, or during equipment testing. E owever, since all subsequent testing has been satisfactorily performed, and the problemn have not recurred, no further

- action is deemed necessary 1

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