The Unusual Event was declared by operators at 8 a.m. CST after Unit 2 experienced a transformer explosion in an electrical switchyard. The interruption of electrical power to Unit 2 caused protective systems to shut down the reactor.

Operators will keep the Unit 2 reactor offline while the cause of the explosion is investigated and a determination is made on what repairs are necessary. Unit 1 remains operating at about 95% power.

No radiation releases have been reported. Power is being supplied to Unit 2 by an emergency diesel generator and one source of offsite power and plant conditions are stable. There are normally two sources of offsite power.

An Unusual Event is the lowest of four nuclear emergency classifications and means events indicate a potential degradation of the level of safety of a plant. The NRC’s senior resident inspector assigned to the site is inside the plant’s control room monitoring the licensee’s response to the event.