One year after cost and schedule estimates were revised, construction of the Watts Bar 2 nuclear plant is 80% complete and remains "on schedule and on budget," according to the Tennessee Valley Authority.

"The project currently is tracking a most likely completion date of December 2015," TVA said, 29 October.

The new estimate to complete, announced in April 2012, estimated the completion date between September 2015 and June 2016. It put the total cost of the project at $4.0-$4.5 billion, which is $1.5-$2.0 billion higher than initially estimated.

"The plant is approximately 80 percent complete, and we are focusing on completing and readying plant systems for pre-operational testing," said Mike Skaggs, TVA senior vice president for Watts Bar Operations and Construction.

TVA noted that three operating systems that are required for open vessel testing were released ahead of schedule from the construction organization for pre-operational engineering tests.

Open vessel testing is the first of five functional tests designed to demonstrate Watts Bar 2 is being built to high standards of quality. It involves pumping water through several systems that are used when shutting down the reactor, as well as support for other nuclear operations. The open vessel testing is scheduled for early 2014, TVA said.

Construction of two 1100MWe Westinghouse PWR reactors at Watts Bar in southern Tennessee began in 1973, and carried on until 1985, when unit 1 was basically finished. Unit 1 was later completed and began operating in 1996. The resumed Watts Bar 2 construction project officially began in August 2007, with completion ‘most likely’ in December 2015.

The Watts Bar Nuclear Plant (Source: TVA)