Costs of a nuclear fuel plant have ballooned by billions due to a lack of controls, according to a new audit.

Construction on the South Carolina facility, known as MOX (the term stands for "mixed oxide fuel") started in 2007. With a $4.8 billion price tag, it was supposed to be completed by 2016.

Nearly six years and $4 billion later, the project is only 60 percent complete, the U.S. Energy Department's inspector general found.

Now, the facility's costs have grown to $7.7 billion, with a new completion date of November 2019.

The National Nuclear Security Administration and the facility's contractor, Shaw Areva, have been "largely unsuccessful in controlling the cost and schedule for the MOX Facility," the IG reported.

Furthermore, the original design of the project was "immature," according to the IG.

The project was part of an Russia-u.s.-to-negotiating-table/article/2546799">agreement in 2000 between the United States and Russia on the mutual disposal of weapon-level plutonium, according to the report.

It would have been the first of its kind in the United States.

The Obama administration 2015 budget put the project into "cold standby," according to the report -- a decision met with strong opposition from South Carolina lawmakers.

Kelly Trice, the president and chief operating officer of Shaw Areva, told employees in March that work on it would continue as normal despite direction from the NNSA or Energy Department, according to the Augusta Chronicle.