Scientists had been worried that flammable gases could have been inside the tank in amounts possibly making opening a vent dangerous. Hanford scientists believe the tank holds about 20,000 gallons of sludge laced with an estimated 66 pounds of plutonium. This sludge is about eight feet deep. This is leftover waste from the PFP's refining days in the Cold War.
Numerous questions exist regarding the sludge's chemical makeup.
Consequently, scientists have to prepare to safely look inside the tank, collect samples, analyze them and then start planning the fix-it work. Originally, they planned to look inside the tank last November. But it took much longer than expected to test the ground above and around the tank to make sure the weight of people and equipment would not collapse it, Clarke said. Also, some coordination issues had to be worked out with Lockheed Martin Hanford Corp., which is the site's expert in underground tanks. And more training for workers was needed than originally planned, she said.