In that same area, crews are now working to cocoon the the N Reactor. They'll build four-foot-thick walls around it to seal it off. It's going to stay that way for 75 years.
That cocooning project is a year ahead of schedule.
"A major focus of the work is to protect the river. We do a lot of things like water mitigation, water erosion and fence around to catch debris that can fall off to the river," Bob Smith of Washington Closure Hanford.
Last year crews demolished the main ventilation unit.