USEC's Paducah, Ky., Gaseous Diffusion Plant declared an alert when powerful tornadoes tore through parts of the Midwest Sunday. The plant sustained damage, but it did not create a threat to the public or the environment.The uranium enrichment plant declared the alert at 2:17 p.m. According to a report filed with the Nuclear Regulatory Commission, USEC later confirmed the storm did not result in injuries or the release of hazardous material. While multiple facilities were damaged, the security fence and protected area remained secure. The alert ended at 6:06 p.m. the same day.A USEC spokesman told the Louisville Courier-Journal that winds from a nearby tornado damaged one of four enrichment production buildings, in addition to cooling towers and a switchyard. The plant had not been in operation since June. Damage was limited to the exterior of the building, and safety systems remained in operation. Across the Ohio River, three people died in or near Brookport, Ill., a few miles away.Unlike at power reactors, where events are divided into one of four categories, the NRC uses only two classifications for emergencies at nuclear fuel cycle facilities. An alert signifies an event that could lead to a release of radioactive material but is not expected to require an offsite response to protect the public.