A new reactor at the Tennessee Valley Authority's Watts Bar Nuclear Plant remains on schedule for completion in December 2015.
Work was initially scheduled for completion in late 2012 at a cost of about $2.5 billion, but last year TVA announced the work was three years behind and would cost $2 billion more than planned.
On Thursday, TVA issued a progress report covering the period from February through April. It found that workers had more than 19.7 million hours without a lost-time accident during that period.
Watts Bar 2 will generate about 1,100 megawatts, enough electricity to supply about 650,000 homes.
TVA is the nation's largest public utility, serving 9 million people in parts of seven southeastern states.