Transformer fires trigger emergency shutdown at Waterford 3 nuclear plant

What happened

Two transformers caught fire in the main transformer yard at Entergy's Waterford 3 nuclear generating plant in Killona. According to the Nuclear Regulatory Commission, the fires led to an emergency SCRAM, a rapid shutdown of the reactor by insertion of its control rods, and the plant's emergency director declared an unusual event, the lowest emergency classification, at 12:09 a.m. on a Friday. A local fire department responded, but the plant's own fire brigade put the fire out.

The unusual event ended at 2:21 a.m. after the fire was extinguished. The generator had not restarted at the time of reporting, and Entergy said the related work should take several weeks. Plant officials notified the Federal Emergency Management Agency and Louisiana emergency officials. The NRC said the fire was contained on site, there was no danger of a radiation release, and no public notification was required because the event did not pose a threat to public health and safety.

Contributing factors

The source does not report why the transformers caught fire.

Lessons learned

1. Keep an on-site fire brigade able to extinguish electrical fires in a main transformer yard, including when an outside fire service also responds.
2. For a low-level nuclear emergency, record clearly which regulators and emergency officials were notified and why no public warning was required.
3. Plan for the plant to remain in a safe shutdown for several weeks while main-yard transformer repairs are scheduled.

Source

nola.com