EN Revision Imported Date : 10/14/2019
EN Revision Text: PART 21 INTERIM NOTIFICATION - FAILURE OF A SIGNAL CONVERTER SUPPLIED TO COOPER NUCLEAR PLANT
The following is a summary of the information received from Engine Systems, Inc. via facsimile:
ESI was notified on April 6, 2019 that a signal converter (also called a signal conditioner) that sends the Reactor Core Isolation Cooling turbine speed to the turbine controller had failed. The converter is at the manufacturer's facility undergoing testing at this time and they have been unable to complete their evaluation within 60-days. The evaluation is expected to be completed by July 31, 2019.
The converter was only supplied to Cooper Nuclear Plant.
* * * UPDATE FROM DAN ROBERTS TO DONALD NORWOOD AT 1710 EDT ON 7/19/2019 * * *
The following is a synopsis of information received via facsimile:
On June 5, 2019, Engine Systems, Inc. (ESI) issued an interim report regarding an identified deviation for which ESI was unable to complete an evaluation within the 60-day requirement. Per the interim report, ESI committed to complete the evaluation by July 31, 2019. The evaluation is now complete and the deviation is determined to be reportable in accordance with 10 CFR Part 21.
ESI supplied the component which failed to comply or contained a defect. That part was a Signal Converter Transmitter, P/N SCT/4-20MA/4-20MA/24DC/-LIM-TA[DCM]. This component was only supplied to Cooper Nuclear Station.
The nature of the defect was that a power inverter transformer, internal to the signal converter transmitter, failed shorted. The transformer failure adversely affected other circuit board mounted components which prevented the device from functioning properly. The signal converter transmitter is a component of a turbine control panel. Within the panel, the transmitter is used to sense the customer's remote speed setpoint input signal and convert the signal which is transmitted to the turbine control. Since the signal converter transmits the customer's remote speed setpoint input to the turbine control, operability of the device is critical to operation of the RCIC turbine control system. Therefore, a failure of the signal converter would adversely affect the RCIC turbine control system and thus may affect the safe shutdown of the reactor.
At Cooper Nuclear Station, the failed component has been removed and replaced with a spare transmitter from a different batch. No further action is necessary.
For ESI, the previous design transformer (used in the failed transformer) was discontinued by the transformer manufacturer in 2016 which required the signal converter transmitter manufacturer to source a new transformer. The new transformer has the same functionality with a slightly different form factor which minimizes the potential for common cause failure with the original style transformer. Therefore, no additional actions are required since a different transformer is in current use. ESI has included a verification of the current transformer design in the commercial grade dedication package.
The names and addresses of the individuals reporting this information are:
John Kriesel Engineering Manager Engine Systems, Inc.; 175 Freight Rd. Rocky Mount, NC 27804
Dan Roberts Quality Manager Engine Systems, Inc.; 175 Freight Rd. Rocky Mount, NC 27804
Notified R4DO (Proulx) and the Part 21/50.55 Reactors E-mail group.
* * * UPDATE FROM DAN ROBERTS TO DONALD NORWOOD AT 1643 EDT ON 10/11/2019 * * *
The following is a synopsis of information received via facsimile:
Subsequent to the issue of the report on July 19, 2019, ESI became aware of another potential defect with the same device. As a result, ESI has amended the report to expand the extent of condition.
ESI supplied the component which failed to comply or contained a defect. That part was a Signal Converter Transmitter, P/N SCT/4-20MA/4-20MA/24DC/-LIM-TA[DCM]. This component was only supplied to Cooper Nuclear Station.
The nature of the defect was that four circuit board mounted components (two transistors, a capacitor, and a diode) failed, causing the device to go to zero output. These prevented the device from functioning properly.
Corrective actions for Cooper Nuclear: As stated above, no further action is necessary.
Corrective actions for ESI for the subsequent failure: ESI has been unable to positively determine the root cause; however, correspondence with the signal converter manufacturer indicates this may be related to the previous style transformer. While no anomalies were detected with the transformer, the failed components are electrically connected to the transformer. Verification of the current style transformer is performed in the commercial grade dedication package.
The names and addresses of the individuals reporting this information are:
John Kriesel Engineering Manager Engine Systems, Inc.; 175 Freight Rd. Rocky Mount, NC 27804
Dan Roberts Quality Manager Engine Systems, Inc.; 175 Freight Rd. Rocky Mount, NC 27804
Notified R4DO (Kellar) and the Part 21/50.55 Reactors E-mail group. |