Wednesday, March 16, 2011

Closing Hanford tanks: How long will they last?

By Jeff Lyon, Tank Waste Storage Project, Nuclear Waste Program

While we retrieve the waste from Hanford’s 149 single-shell waste storage tanks, one of our concerns is how long these tanks can last. We know they were built tough, but we also know they have been stretched to their limits. The tanks were constructed as part of the Manhattan Project during World War II, when knowledge of the temperature of high-level waste (HLW) was unknown. And because it was war time, there may have been a shortage of stainless steel, which would affect the construction of these tanks.

We are about ready to wrap up the planning efforts to core, sample, and test a single-shell tank concrete wall. This will help determine the current integrity of the sampled tank and give us clues about the other tanks and their ability to continue safely storing HLW.

When we complete our planning meetings, the US Department of Energy will write a Data Quality Objectives report and a Sampling and Analysis Plan. After these documents are finished, they will be available on the Tri-Party Agreement (TPA) Administrative Record and Public Information Repository.

Then the field planning, drilling, sample collection, and analyses will begin. Check out our TPA changes (number M-045-10-01) to see what other work we have planned to ensure SST structural and leak integrity. As we complete these milestones, this information will help us ensure that these tanks are still able to hold waste until they are emptied (presently planned to be completed by January 2043).

Regardless of the integrity of the tanks, our near-term focus is for closing tanks one farm at a time. Our first is Tank Farm C (C-Farm). Much planning is required for retrieving the radioactive and dangerous HLW, investigating spills, and closing the tank farms. We continue to plan soil cleanup and are deciding which tanks to retrieve next.

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