ENS 49249
ENS Event | |
|---|---|
07:05 Aug 8, 2013 | |
| Title | Alert Declared Due to a Switchgear Explosion That Supplies Safe Shutdown Equipment |
| Event Description | The licensee reported that there was an explosion in a non-safety related electrical bus (Bus 1E2). The bus is designated as a safe shut down bus. The licensee has classified this event as an Alert based on an EAL entry condition of "an explosion of sufficient force to damage permanent structures or equipment within the Protected Area." The licensee is still investigating what loads come off this bus but no safety-related loads have been identified at this time. The plant is currently stable at 92% power. Power was reduced due to the loss of moisture separator reheaters on the secondary side as a result of this event. There is no ongoing fire as a result of the bus explosion. No personnel were injured. No damage to other equipment has been identified at this time.
The licensee has notified state and local authorities and the NRC Resident Inspector. Notified DHS SWO, DOE, FEMA, HHS, DHS NICC, USDA, EPA, FDA and NuclearSSA via email. NRC PAO (Brenner) notified.
Auxiliary bus 1E2 (safe shutdown equipment bus) is de-energized due to the explosion. The Alert was declared due to the explosion affecting safe shutdown equipment." The licensee also noted that the event was initially classified as an Unusual Event at 0234 EDT and then upgraded to an Alert classification at 0305 EDT when the bus was determined to supply safe shutdown equipment. The licensee has notified the NRC Resident Inspector.
No offsite assistance was requested during this event. The licensee verified that there was no fire. It was noted that the licensee is in Technical Specification Action Statement 3.8.1.1 for the "B" Emergency Diesel Generator being out of service. The EDG is out of service due to loss of power to the "C" and "D" air compressors. The licensee was uncertain if the loss of these air compressors was related to the event. The licensee has notified the NRC Resident Inspector. R2DO (Shaeffer) and NRR EO (Hiland) notified.
The licensee terminated the Alert declaration at 0533 EDT based upon no fire at Bus 1E2 and verification that Bus 1E2 is de-energized and disconnected from all electrical systems. The licensee remains at 92% power. The only noted safety related equipment that was impacted is the "1B" Emergency Diesel Generator which has been declared inoperable due to loss of power to associated air compressors "1C-SB" and "1D-SB. The licensee has notified the NRC Resident Inspector. R2DO (Shaeffer), NRR EO (Hiland) and IRD MOC (Morris) notified. Notified DHS SWO, DOE, FEMA, HHS, DHS NICC, USDA, EPA, FDA and NuclearSSA via email. NRC PAO (Brenner) notified.
It has been determined that operability of the 1B Emergency Diesel Generator (EDG) was not affected by the damage to 480 volt auxiliary bus 1E2. The 1C and 1D starting air compressors for 1B EDG did not lose power and thus the 1B EDG was operable. The NRC Resident Inspector has been notified. Notified R2DO (Shaeffer). |
| Where | |
|---|---|
Harris  North Carolina (NRC Region 2) | |
| Reporting | |
| Emergency class: | Alert |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration | |
| Time - Person (Reporting Time:+-3.83 h-0.16 days <br />-0.0228 weeks <br />-0.00525 months <br />) | |
| Opened: | Maria Powers 03:15 Aug 8, 2013 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Aug 10, 2013 |
| 49249 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (92 %) |