Georgia Power has sent additional workers to oversee its nuclear reactor expansion project at Plant Vogtle, a move to meet stricter company and federal regulatory standards, a company spokesman said.

But adding workers has led to “emerging challenges respecting owners’ costs,” according to company documents filed late Friday afternoon.

“We needed additional people and resources for oversight on this project,” Georgia Power spokesman Mark Williams said. “We certainly want to meet the standards that we set forth as a company and what the Nuclear Regulatory Commission had, and we needed more people.”

The company didn't disclose how many extra workers are on site or say how much costs will rise.

Georgia Power is part of a group of utilities that want to build two reactors at Vogtle, which is near Augusta.

The utility must file construction monitoring reports with the Georgia Public Service Commission every six months. Friday’s documents cover the six months from January to June 2011 – the same time in which Japan was cleaning up after a meltdown at its Fukushima Daiichi nuclear plant.

The NRC has made seven safety recommendations based upon the Fukushima accident since that time.

Southern Nuclear, Georgia Power’s sister company, will operate the reactors. Southern is waiting on a key license from federal regulators.

Georgia Power is responsible for $6.1 billion of the estimated $14 billion project. Despite noting cost “challenges,” the utility said the project is expected to be $18 million under budget.

Georgia Power is trying to return the project’s schedule to its original time frame, which would have the first reactor start producing power in April 2016. Regulatory delays had pushed back the start date to June 2016.