TVA spokesman Terry Johnson said the plant is expected to come on line in mid-May, subject to tests at the site.

"Virtually all of the physical work has been done," he told Reuters in a telephone interview on Friday. "As the components are tested, it's possible that things will show up that may take a couple of hours or a couple of days."

The reopening would mark the first addition to the US fleet of operating nuclear power reactors since 1996. Nuclear plants account for about 10 percent of US power generation.

While Browns Ferry Unit 1 -- which would be the 104th US operating reactor -- is not new, industry advocate Nuclear Energy Institute called its reopening the start of a US nuclear renaissance.

"I think this definitely marks the beginning," NEI spokesman Mitch Singer told Reuters. "When historians look back at this as the real first concrete beginning of the nuclear renaissance in the United States."

TVA, a federal agency, shut all its nuclear power plants in 1985 because of poor management and the need for costly overhauls. While some reopened, Browns Ferry 1 did not.

The "No Nukes" campaign in the United States in the mid 1980s was bigger than it is now, when even some environmental groups see nuclear power as a way to make electricity without climate-changing greenhouse gas emissions.

Browns Ferry began operation in 1974 and just a year later, closed briefly after a worker using a candle to check for leaks in a small tunnel caused a fire that burned unchecked for seven hours. No one was injured and no radiation was released but it was a black eye for the TVA and Browns Ferry.

Singer said as many as 15 companies are planning 34 new nuclear power reactors, although none have yet filed for an operating license with the US Nuclear Regulatory Agency. No new licenses have been given since 1973.

The first new reactor is likely to open between 2014 and 2016, the NEI says.

In 2002, the TVA approved spending $1.8 billion to reopen the Browns Ferry reactor. When it opens, it will be able to serve about 650,000 homes.

One of the plants where construction was stopped before it was ever opened was in Bellefonte in northern Alabama. The TVA ordered a halt to construction in 1988 at a time when it did not need the generating capacity.