The Tennessee Valley Authority is celebrating the completion of the first new nuclear unit in the United States in the 21st Century. The utility says Unit 2 at the Watts Bar Nuclear Plant has achieved full power output following the completion of construction. Construction for the reactor was first started in 1979 then restarted in 2008. The reboot ran about 42 billion over budget and took about three years longer than anticipated. Officials say that safety remains a top priority and that will be a focus as the new unit is integrated into the fleet.