Gas generation and retention in Tank 101-SY: A summary of laboratory studies, tank data, and information needs

Chemical and radioactive wastes from processes used to separate plutonium from uranium are stored in underground tanks at the Hanford Site in Washington state. In March 1981, it was observed that the volume of wastes in Tank 101-SY slowly increased, followed by a rapid decrease and the venting of large quantities of gases. These cycles occurred every 8 to 15 weeks and continue to the present time. Subsequent analyses showed that these gases were composed primarily of hydrogen and nitrous oxide (N{sub 2}O). In response to the potential for explosion and release of hazardous materials to the environment, laboratory programs were initiated at Argonne National Laboratory (ANL), Georgia Institute of Technology (GIT), Pacific Northwest Laboratory (PNL), and Westinghouse Hanford Company (WHC), to develop a better understanding of the physical and chemical processes occurring in this waste tank. An aggressive sampling and analysis effort is also under way to characterize the wastes as fully as possible. These efforts will provide a technically defensible basis for safety analyses and future mitigation/remediation of the tank and its contents.