Semantic search
Jump to navigation
Jump to search
| Entered date | Event description | |
|---|---|---|
| ENS 51282 | 1 August 2015 15:28:00 | At 1205 CDT on August 01, 2015, the station's Seismic Instrumentation generated a seismic event alarm that was determined to be invalid, based upon no seismic activity being felt on site and no activity detected in the area by either the National Earthquake Information Center or nearby nuclear plants. The instrumentation that actuated, recorded a value of 0.07 g on a single axis of one instrument, which is greater than the 0.02 g threshold value in the Emergency Action Level in the station's emergency procedures; however, no other instrument channel or axis indicated a valid event exceeding the 0.02 g threshold. Since the event alarm was determined to be invalid as described above, no EAL thresholds were met. The seismic instrumentation was declared non-functional since it would not generate a seismic event alarm during an actual event until the invalid event was reset. The alarm was reset through the alarm reset process. The seismic instrumentation alarm capability was restored and returned to service at 1250 CDT. This resulted in a Loss of Emergency Assessment Capability while the Seismic Instrumentation was out of service. This is a reportable condition in accordance with 10 CFR 50.72(b)(3)(xiii). The licensee has notified the NRC Resident Inspector. The licensee performed a channel calibration in response to the previous Seismic Instrumentation malfunction (see EN # 51263) and plans to perform more extensive troubleshooting in response to the latest malfunction. The licensee will notify the State of Illinois plant inspector. |