The inspectors opened a
URI to facilitate the completion of inspection and determination of whether a performance deficiency was associated with the start failure of the B ESCW chiller on May 13, 2017. Description: On May 13, 2017, while attempting to start the B ESCW chiller, the motor compressor immediately tripped on C phase instantaneous overcurrent relay actuation. The chiller was declared inoperable and immediate troubleshooting was conducted to determine the cause of the trip. The licensees initial investigation did not identify any electrical or mechanical issues with the compressor motor, supply breaker and electrical bus, or other chiller control components. While the calibration of the C phase instantaneous overcurrent relay was checked and found to be within specification, the licensee determined the most probable cause of the trip was an intermittent failure of this relay. The relay was replaced and subsequent post-maintenance testing of the chiller was successfully performed without any other chiller operational problems being identified. The chiller was returned to operability early May 14, 2017, following the completion of this post-maintenance testing. At the end of the inspection period, the licensees investigation into the cause of the start failure had just completed. A
URI is being opened for the NRC to review the licensees failure analysis and causal evaluation to determine whether the chiller start failure was reasonably within the licensees ability to predict or prevent and therefore a performance deficiency. This issue is being tracked as
URI 05000400/2017002-02, B ESCW Chiller Failure to Start
