ML20035C584
| ML20035C584 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 04/05/1993 |
| From: | Stimac S COMMONWEALTH EDISON CO. |
| To: | Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9304080143 | |
| Download: ML20035C584 (5) | |
Text
.
Commonwocith Edison i
m 1400 Opus Place Downers Grove, lilinois 60515 April 5, 1993 Dr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Attn:
Document Control Desk
Subject:
Zion Station Unit 2 Eagle 21 Process Protection System Periodic System Performance Report NAC_ Docket No. 50-304
Reference:
April 10, 1992 letter from S.F. Stimac to T.E. Murley
Dear Dr. Murley:
Commonwealth Edison Company (CECO) committed via the reference to provide NRC periodic performance reports related to the Zion Unit 2 Eagle 21 Process i
Protection System.
The installation and testing of Eagle 21 was recently
)
completed at Zion Unit 2.
Pursuant to this commitment, please find enclosed j
one copy of " Zion Station Unit 2 Eagle 21 System Performance Report," dated April 5, 1993.
As described in the reference, additional performance reports 1
will be submitted periodically throughout the first Unit 2 operating cycle with Eagle 21.
Please direct any questions you may have to this office.
Respectfully, Stephen F. Stimac 1
Nuclear Licensing Administrator
]
Enclosure cc: A. Bert Davis, Regional Administrator - RIII C.Y. Shiraki, Project Manager - NRR J.D. Smith, Senior Resident Inspector - Zion Office of Nuclear Facility Safety - IDNS 1
ZNLD/2571/1 080010 9304080143 930405 h
t PDR ADOCK 05000304 P
ZION STATION UNIT 2 EAGLE 21 SYSTEM PERFORMANCE REPORT April 5, 1993 LNSIALLAIIDN_AND START-UP TESTING Several days after Westinghouse testing was completed in Protection Set III, rack #12, the Test Sequence Processor (TSP) was found in the " Diagnostic Failure" mode.
Action Taken: The TSP board was reseated and reset.
The rack was checked on a daily basis, and several days later the same condition appeared.
The TSP board was then replaced.
Cause:
The cause of the board failure is presently unknown.
The defective board was sent 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.
i Due to a design drawing discrepancy between Internal Hiring Diagrams and the Process Block Diagrams, the Eagle Partial Trip (EPT) boards in rack #11, terminal frame 5 and rack #15, terminal frames 7 and 8 were configured as j
internally pswered for the Refueling Water Storage Tank (RHST) Low and Low-Low Level alarm channels.
Each EPT circuit board is divided into four identical trip channels.
These trip channels can be either externally powered or internally powered.
EPT channels that are used for alarm purposes only are typically externally powered.
This error was discovered during Site Acceptance Testing (SAT).
Action Taken: The boards were removed and reconfigured for external power on site. All subsequent SAT tests were satisfactory and no apparent damage to the boards resulted from this error.
The appropriate design drawings were revised to reflect an externally powered configuration for the RHST channels.
Cause:
The cause is attributed to a design drawing discrepancy.
Typically, most channels on EPT boards are internally powered since they provide trip signals.
However, the RHST channels provide annunciation only, and are externally powered by the annunciator system.
Since very few externally powered channels exist, the reviewer could have easily misinterpreted the configuration on design drawings. All other EPT boards at Zion were tested satisfactorily for proper function and configuration.
ZNLD/2571/2
4 INSJALLATIo w Dl IARI.UP TES11NG_(Continuedl During Eagle 21 construction testing performec by CECO, it was observed that loss of the secondary 15Vdc power supply would not produce a trouble light in rack #12, Protection Set III.
The Eagle 21 system is designed to actuate a test panel trouble light, and send an error j
signal to the Man Machine Interface, on loss of either the primary or j
secondary power supplies.
Action Taken:
Originally, the problem was thought to be a defective Digital to Digital Converter (DDC) board.
The board was replaced, but the problem was still present.
The original DDC board was reinstalled, and the secondary power supply was replaced.
This did not eliminate the problem.
Further investigation revealed a pin on the connector for the sense signal, at the Multibus backplane was not properly seated.
The pin was reinstalled and results of retests were satisfactory.
Prior to the secondary power supply replacement, it was observed that the power indicating Light Emitting Diode (LED) for 15Vdc power supply was blown on the original unit.
The power supply voltages were verified to be correct.
However, this power supply was not reinstalled when the actual root cause of the problem was discovered.
The power supply was sent to Westinghouse for LED replacement.
Cause:
When pin type connectors are mated there is the potential for pin misalignment.
In order to insure that this type of problem does not go undetected multiple stages of rack testing were performed before the rack was declared operable.
The power supply with a blown LED was sent back to Westinghouse for repair.
The root cause is believed to be a defective LED.
This component failure has no impact on the ability of the power supply to perform its intended function.
ZNLD/2571/3
INSIAl.LAUDN_AND START-UP TESllNG_1 Continued 1 During Eagle 21 construction testing, performed by CECO personnel, it was observed that the test panel test point for Loop B Steam Flow was not supplying a signal.
This signal is an indication of Steam Flow transmitter output, and is a direct connection from the Eagle Analog Input board (EAI) J4 connector to the Eagle test panel.
Action Taken:
The J4 connector was removed from the EAI board to verify continuity.
It was then observed that the connector pin, associated with the test point signal, was in the wrong pin hole location.
The appropriate documentation was initiated to record the finding.
The connector pin was also relocated to reflect design drawings.
Subsequent testing was performed satisfactorily.
Cause:
The cause for this event is attributed to manufacturing error.
Testing performed by Westinghouse, at the factory and onsite, should have identified this problem.
However, one possible explanation for the error is that since the Digital Voltmeters used for testing hold the previous value read, if not zeroed, a value from the previous test point could have been read as measurements were taken across the test panel.
In order to insure this problem is not prevalent in other racks, multiple stages of testing were performed. All other racks were determined to be free of this problem.
During Eagle 21 Power Up Sequence testing, it was observed that the rack #3, Protection Set I, Loop Calculation Processor (LCP) startup time was unacceptably fast. This LCP is supposed to start in approximately 2 seconds, testing showed start times as low as 300ms.
Action Taken:
The rack #3 Power Distribution Panel, which houses the time delay relays for rack component startup, was replaced.
Subsequent retesting showed acceptable start times for all rack #3 components.
Cause:
The cause of this failure is presently unknown.
The affected Power Distribution Panel was shipped 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.
ZNLD/2571/4
4
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OPlRAU0NALPIREORM8ELUhrSughda1Ih 29.19331 On February 13,.1993, Unit 2 was in Mode 3 at an RCS temperature of 455 degrees and increasing, when operating personnel noticed that the Loop B Tave indicator was pegged low.
The Loop B Delta T/Tave channel is processed through rack #15 of Protection Set IV.
Action Taken:
Dynamic information for the Delta T/Tave channel was reviewed on the Eagle Man Machine Interface.
It appeared that the signal coming into Eagle 21 from the Resistive Temperature Detectors (RTDs) was causing the problem.
The Delta T/Tave channel RTD wiring was inspected and compared to other Protection Set Delta T/Tave channel RTD wiring.
It was then discovered that a wiring problem existed.
It was determined that the Loop B RTDs were installed per one of three design drawings that illustrate the associated rack wiring.
However, the drawing used was incorrect, and resulted in the RTDs being connected in such a way that Eagle RTD Input 1
(ERI) boards sensed a negative input signal and consequently caused the channel to fail low.
The RTD wiring was changed to reflect the correct design drawings.
The channel was returned to service with no further problems.
The appropriate actions were initiated to correct the drawing found to be in error.
Cause:
The associated wiring was performed under a Field Change Request (FCR) to an existing Eagle 21 modification drawing package.
This FCR correctly described the internal wiring in rack #15, but incorrectly described the associated field wiring.
This was due to a transposition error of terminal point numbers for field wiring locations. All other Delta T/Tave channel RTD wiring was verified to be correct subsequent to the initial faliure.
7NLD/2571/5
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