The federal government has cleared the way for construction of the Uranium Processing Facility's three main buildings at the Y-12 nuclear weapons plant, triggering plans for the hiring of about 400 project workers.

The project has been underway since 2014 with a projected completion of 2025. It's composed of seven "subprojects." Two, including site grading and a construction support building, are now done.

A limited liability company that includes Bechtel Inc. is building the estimated $6.5-billion project in Oak Ridge. It's one of the largest in the state's history, and one of the largest sought by the National Nuclear Security Administration.

The complex will replace a World War II-era facility. Uranium is a component in nuclear weapons that's stored and processed at Y-12.

Source: Bechtel

According to Consolidated Nuclear Security, which operates Y-12, the 400 workers will be coming on in the coming months.

Ultimately about 900 skilled craft employees and 1,000 professional services personnel will be hired.

The three main facilities are what's called the Main Process Building, the Salvage and Accountability Building and Process Support Facilities.

In a statement released Tuesday, UPF project director John Howanitz said activity at the site will now pick up significantly, with more people doing more things at the site.

The UPF has been planned for years. Original plans envisioned a single large building but estimated costs escalated far beyond $6.5 billion.

Revised plans show the top cost at $6.5 billion.