period of outage. An NRC Unusual Event, the lowest level of emergency classification, was declared due to loss of power exceeding 15 minutes. Additionally, a small oil leak was found on one generator. Due to widespread transmission grid damage from the storms, Browns Ferry was unable to produce power for the grid and significant blackouts occurred throughout the Southeastern United States. January 2015 A drain line leaked 100-200 gallons of water containing tritium levels above acceptable EPA drinking water standards. The leak was fixed within three hours of when it was discovered and was largely contained within the plant area. May 2015 The Nuclear Regulatory Commission found that 5 contract workers failed to conduct roving fire watch patrols as required by NRC. As a result, Tennessee Valley Authority was fined $140,000 for failing to maintain adequate fire watches in 2015 at Browns Ferry. Surrounding population The 2010 U.S. population within of Browns Ferry was 39,930, an increase of 12.3 percent in a decade, according to an analysis of U.S. Census data for msnbc.com. The 2010 U.S. population within was 977,942, an increase of 11.0 percent since 2000. Cities within 50 miles include Huntsville (28 miles to city center). Seismic risk According to an NRC study using geological data from 1989 to 2008 which was published in August 2010, the estimated risk of an earthquake intense enough to cause core damage to reactor one was 1 in 270,270, and for reactors two and three, the risk was 1 in 185,185. See also List of largest power stations in the United States Largest nuclear power plants in the United States New Madrid Seismic Zone 1811–12 New Madrid earthquakes Notes References External links TVA Website The Fire at the Brown's Ferry Nuclear Power Station, by David Dinsmore Comey, 1976. NIRS Investigation Finds That "New" Browns Ferry-1 Reactor Still Doesn't Meet Fire Protection Regulations Its 1975 Fire Caused Nuclear Information and Resource Service, June 20, 2007. TVA reactor shut down; cooling water drawn from river too hot Reactor Fire Protection 10CFR50.48, NRC Summary Climate change causes nuclear, coal plant shutdowns June 4, 2012 USA Today, regarding the effects of global warming Energy infrastructure completed in 1973 Energy infrastructure completed in 1974 Energy infrastructure completed in 1976 Nuclear power stations using boiling water reactors Civilian nuclear power accidents Nuclear power plants in Alabama Buildings and structures in Limestone County, Alabama Tennessee Valley Authority Nuclear accidents