ML20057B416
| ML20057B416 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 09/16/1993 |
| From: | Simpkin T COMMONWEALTH EDISON CO. |
| To: | Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9309210318 | |
| Download: ML20057B416 (5) | |
Text
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O_1 Commonwesith Edisen 1400 Opus Place V
Downers Grove, Illinois 60515 September 16, 1993 Dr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Attention: Document Control Desk
Subject:
Zion Station Unit 1 Eagle 21 Process Protection System Periodic System Performance Report NRC Docket No. 50-295
References:
(a)
April 10, 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 1 Eagle 21 Process Protection System.
Pursuant to this commitment, please find encloced one copy the subject report for the interval of May 16, 1993 through September 15, 1993.
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.
Respectful.ly, M.
T.W. Simpk n Nuclear Licensing Administrator TWS/gp Enclosure cc:
Regional Administrator - RIII l
C.Y. Shiraki, Project Manager - NRR l
J.D.
Smith, Senior Resident Inspector - Zion Office of Nuclear Facility Safety - IDNS i
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ZION STATION UNIT 1 I
EAGLE SYSTEM PERFORMANCE REPORT Spurious Protection Set " Trouble" alarms have been periodically generated from Protection Set III since March 1, 1993.
This is'
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part of the on going investigation identified in the previous i
Unit 1 Eagle 21 Performance Report.
Action Taken: On May 21, 1993, and July 10, 1993 diagnostic EPROM's were installed in racks 11 and 12 of Protection Set III.
This was done because the speed that the spurious alarms would annunciate and clear made it difficult to utilize the Man Machine Interface (MMI) to capture the error codes
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associated with the alarms.
To resolve this problem, Westinghouse modified the software in the Test Sequence Processor (TSP) to capture and output the error code when an alarm is generated.
j On August 15, 1993, a spurious alarm from Protection Set III rack 11 was generated.
The error code that caused the alarm was a 302, which means a bistable tripped when the Loop t
Calculation Processor (LCP) did not call for the channel to be tripped.
An investigation into the alarm revealed that the control room did not receive indication of a bistable trip to validate i
the error code.
l On August 27, 1993, a' spurious alarm was generated
[
l on Protection Set III rack 12.
The error code l
l that was generated was a 204, which means that there was a communication failure between the TSP l
and LCP.
Root Cause:
It has been decided to keep the EPROM's in Protection Set III to see if the same error codes are repeated.
An update will be provided in a follow up report.
On June 21, 1993, a " Channel Set Failure" alarm was received j
from Protection Set I.
Action Taken: An investigation into the alarm revealed that the TSP for rack 3 had halted.
Attempts to use the MMI to obtain an error code were unsuccessful due j
i to the TSP being in a non-functioning state.
Several attempts were made to reboot the TSP by l
depressing the reset push button on the status panel.
Each attempt to reboot the TSP was unsuccessful.
As a result of this,.the TSP board 1 of 4
i i
l was replaced and the nece.ssarv checks performed to confirm that the board was functioning properly.
Root Cause:
The cause of the failure is unknown at this time.
The board has been returned to Westinghouse for a failure analysis.
Results of the failure analysis j
will be provided in a follow up report.
l On July 23, 1993, a " Channel Set Failure" alarm came in from Protection Set I.
Action Taken: An investigation into the alarm ' revealed that the LCP for rack 2 had halted.
The MMI was plugged into rack 2 to determine what error code was associated with the alarm.
Error code 104 was displayed, which means a LCP/ TSP communication failure.
The Data Link Handler (DLH) board on the LCP side of the card cage was replaced.
Prior to replacing the board, the LCP was successfully rebooted by depressing the reset push button on the status panel.
It was decided to proceed with the replacement of the DLH board in case there was an intermittent problem with it.
Root Cause:
The board has been returned to Westinghouse for a failure analysis.
Results of the failure analysis will be provided in a follow up report.
During a lightning storm on July 25, 1993, a "RTD Failure" and a
" Trouble" alarm came in from Protection Set IV.
Action Taken: A walk down of Protection Set IV revealed that i
rack 15 was the source of the alarm.
The MMI was utilized to determine which Resistive Temperature i
Detector (RTD) was the problem.
The dynamic display on the MMI revealed that 1TE-441 was reading higher than 1TE-440.
Resistance readings of the loop revealed that the RTD was open.
The RTD was removed from scan via the MMI and is scheduled to be replaced during the upcoming outage.
Root Cause:
A lighting strike is being attributed to the root cause of the RTD failing open.
On August 15, 1993, a " Trouble" alarm came in from Protection Set I.
Action Taken: A walk down of Protection Set I revealed that rack 1 was the source of the' alarm.
An examination of the rack indicated that the LED 2 of 4
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for the Primary 15 volt power supply was out.
The error code obtained from the MMI confirmed that the Primary 15 volt power supply had failed.
The power supply was replaced and the appropriate i
power supply adjustments and voltage verifications were performed.
Root Cause:
The cause of the power supply failure is presently unknown.
The power supply will be returned to i
Westinghouse for a failure analysis.
The results of the failure analysis will be provided in a follow up report.
On August 26, 1993 a " Channel Set Failure" alarm came in on Protection Set I.
Action Taken: An investigation into the alarm revealed that rack 2 was the source of the alarm.
A inspection of the rack revealed that the LCP had halted.
The MMI was plugged in to read the error code.
Error code 104 was displayed, which means a communication failure between the LCP and TSP.
Several attempts were made to reboot the LCP by j
depressing the reset push button on the status panel.
Each attempt was unsuccessful.
As a result of this, the LCP board was replaced, and j
the necessary functionals were performed to verify j
that the rack was functioning normally.
l Root Cause:
The root cause of the board failure is unknown.
The LCP board has been sent back to Westinghouse for a failure analysis.
The results of the analysis will be submitted in a follow up report.
On August 30, 1993, a " Trouble" alarm was received from Protection Set I in conjunction with the bistable for FC-532 High Steam Flow Safety Injection tripping.
Act on Taken: An investigation into the alarm revealed that Rack d
3 was the source of the alarm.
The MMI was used to determine what error was associated with the alarm.
Error code 302 was displayed, which means that the a bistable channel is tripped when the LCP is not calling for the channel to be tripped.
The EPT board was replaced, and the appropriate funtionals performed to verify the operability of the new board.
Root Cause:
The cause of the 532 channel on the EPT board failing is not known.
The board has been sent back to Westinghouse for a failure analysis report.
When the results of the report are known it will be submitted in follow up report.
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On September 1, 1993, a " Channel Set Failure" and a " Trouble" alarm were received from Protection Set I.
Action Taken: A visual inspection of rack 1 revealed that the LED's for the status panel and the secondary power supply were cycling on and off.
A check of the LCP revealed that it was functioning properly.
Further inspection of the rack revealed that the light within the power distribution panel rocker.
switch, was cycling on and off at the same frequency as the LED's on the tester panel and secondary power supply.
The power distribution i
panel was suspected to be the source of the problem.
An inspection of the power distribution panel revealed that the wrong rocker switch was blinking.
The light on the TSP rocker switch should have been cycling based on the fact that l
the Tester side of the rack was cycling, but it i
was the light on the LCP rocker switch which was cycling.
It was discovered that the in coming field cables for the power distribution panel were swapped.
This resulted in the LCP being powered from the secondary power supply, and the TSP being powered from the primary power supply.
This had no impact on the f. unction of_ the rack during normal operation.
The timing sequence of the new power distribution panel was verified to be correct prior to installation.
The field wiring was corrected to the proper configuration.
Functionals were performed for several loops in the rack to ensure that the TSP and all its associated hardware did not suffer any damage as a result of the power supply cycling on and off.
Root Cause:
The failure of the power distribution panel is being attributed to a faulty timing relay within the panel.
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