Crews at the Y-12 National Security Complex have completed final concrete placement for a tunnel that will connect major sections of the Uranium Processing Facility (UPF’s) enriched uranium mission.
The project—known as the Highly Enriched Uranium Materials Facility Connector (HCON)— is “in the dry,” signifying completion of the tunnel roof, allowing installation of internal systems such as ventilation, fire protection and security infrastructure, according to a Y-12 press release.
Y-12 is a facility overseen by the National Nuclear Security Administration (NNSA) at the Department of Energy’s Oak Ridge Site in Tennessee. The Bechtel-led joint venture Consolidated Nuclear Security is the prime contractor in charge of management and operations at Y-12.
“With the completion of HCON, we have finished UPF’s last structural skyline change at Y‑12,” the release said. “UPF’s building lines are now complete, and will be seen by everyone at Y‑12 for decades to come.”
The underground connector will link UPF with the Highly Enriched Uranium Materials Facility, enabling direct, protected transfers of nuclear materials and reducing the need for above-ground transport.
According to the press release, construction required roughly 4,900 cubic yards of concrete, 22 tons of reinforcing steel and more than 37,000 labor hours, and was completed about 10 months ahead of schedule.
The tunnel is expected to play a central role in UPF’s long-term operations by improving efficiency and reducing risk in material movement between storage and processing functions.
UPF is NNSA’s next-generation factory for nuclear-weapons secondary stages. Once construction is complete, UPF will replace facilities from World War II.
With structural work complete, the project will transition to systems installation and integration as UPF moves toward completion later this decade.