"The Nuclear Regulatory Commission is working closely with operators at three nuclear plants to ensure continued safe and secure operations in the aftermath of Hurricane Katrina. As a precautionary measure, the Waterford 3 nuclear plant near Taft, La., shut down when a hurricane warning was issued for St. Charles Parish on Saturday. It remains in an Unusual Event, the lowest of four emergency action levels. Electrical power for key safety systems on site is being supplied by the plants standby diesel generators, following a loss of offsite power caused by instability in the regional electrical grid."
Nuclear Regulatory Commission: http://www.nrc.gov/