In 2002, TVA began work to restart a previously mothballed nuclear reactor at Browns Ferry Unit 1, which was completed in May 2007. In 2004, TVA implemented recommendations from the Reservoir Operations Study (ROS) on how it operates the Tennessee River system (the nation's fifth largest). In 2005, the TVA announced its intention to construct an Advanced Pressurized Water Reactor at its Bellefonte site in Alabama (filing the necessary applications in November 2007). In 2007 it announced plans to complete the unfinished Unit 2 at Watts Bar.