GREENEVILLE, Tenn. (WVLT) -- The TVA board of directors gave the go ahead to continue building the second generating unit at its Watts Bar Nuclear Plant, despite a price tag that's swelled by $1.5 to $2 billion.

“TVA expects Watts Bar Unit 2 to be among the best operating and most economical nuclear generating facilities of the 21st century,” TVA President and CEO Tom Kilgore told the board.

The revised estimate will bring the total cost of the facility to somewhere between $4 billion to $4.5 billion, with the most likely target being about $4.2 billion. The utility is hoping to have it completed in the fourth quarter of 2015.

TVA released the revised estimate in early April after new leadership was installed and a seven-month, top-to-bottom analysis of the construction project was completed.

The approval comes as board members were informed that while operating topped $5 billion, a mild winter and slowly recovering economy the company's net income was $347 million lower than expected for the first half of the fiscal year. TVA now expects revenues to end up between $500 and $600 million below expectations.