Nuclear facility lockdown cleared – no contamination

The Hanford Vit nuclear waste processing facility went on lockdown due to an incident with some of the underground tunnels.

Employees at the facility were told to “take cover” for about 6 hours Friday and not to eat or drink anything until the all clear is given because steam was coming from one of the site’s tunnels, the company in charge of building the plant said.

The U.S. Department of Energy Richland Operations Office has completed investigations near the Plutonium Uranium Extraction (PUREX) facility Tunnel 2, with no contamination above background levels discovered.

Shortly before 6:00 a.m. on Oct. 26, workers in the area noticed steam coming from a structure on the north end of the tunnel. As a precaution, workers in the 200 East Area, in the center of the Hanford Site, took cover inside buildings until inspections confirmed no radiological release. Once surveys were completed at about 12:15 p.m., the precautionary take cover was lifted.

Lights and cameras placed inside the tunnel to support stabilization efforts showed steam in the tunnel, resulting from the curing of the engineered grout recently placed in the tunnel to stabilize it. The curing process generates heat and moisture. When the warm moist air left the tunnel and interacted with the cool early morning atmosphere, steam was visible. The steam left the tunnel from an opening in the structure that houses equipment to move a large door used to access the tunnel for placement of railcars containing contaminated equipment inside the tunnel. The structure is original to the tunnel, which was completed in 1964. Cars were last placed in the tunnel in 1996. The opening in that structure was sealed; crews are checking the integrity of that sealing.

Efforts to stabilize the tunnel, evaluated to be at high risk of collapse, began Oct. 1. As of Oct. 25, crews placed about 9,000 cubic yards of grout in the tunnel, which is about 23-percent of the estimated quantity of grout needed to fill the 1,688-foot-long tunnel.

Prior to, and during, stabilization efforts, radiological conditions remained stable in the tunnel, with no airborne contamination detected. Over the next few days, crews will evaluate the covering of the opening in the structure, after which stabilization activities will continue.

The Hanford site, near Richland, Washington, produced plutonium for nuclear weapons from the 1950’s until 1988 and is now a burial and disposal site for nuclear materials.

The incident is the second “take cover” incident within 18 months as a tunnel in the same complex collapsed last May. No workers were injured in the collapse, and officials detected no release of radiation at that time. However, a month later, the US Department of Energy warned that another waste-filled tunnel was at high risk of collapsing as well.

Editor’s Note: This story was updated to reflect the outcome of the DOE’s investigation into what caused the incident.