Technology
Overview
Eliminating the Risk
Eliminating the risk to the environment posed by radioactive and chemical waste in Hanford’s aging underground storage tanks poses one of the most complex cleanup challenges in the Department of Energy complex. The waste includes materials from years of World War II and post-war weapons productions, which accounts for approximately 6 percent by volume of the nation’s high-level radioactive waste. These aging tanks are approximately 10 miles from the Columbia River and within a 50-mile radius of more than 200,000 residents. It is the responsibility of WRPS to reduce this risk and safely manage the waste until it is prepared for disposal.
The Challenges
There are 149 aging single-shell tanks, many of which have leaked as much as one million gallons to the surrounding soil. Risk reduction began several years ago with the transfer of most of the pumpable liquids from the aging single-shell tanks to Hanford’s 28 newer and safer double-shell tanks, leaving behind mostly dry saltcake and sludge materials.
The nature of the waste and the environment inside the tanks defy conventional approaches, requiring that all work inside the tanks be performed by remote control. Further, the tanks were designed to put waste in, not take it out, which created a number of additional physical challenges to the cleanout process. In addition, the variety of waste forms still in the tanks requires a variety of tools to remove them. No single tool is adequate to remove the waste to a level that meets Tri-Party Agreement requirements. Washington River Protection Solutions has extensive experience working under such constraints and is applying technological innovation combined with ingenious engineering to safely and successfully complete this hazardous and complex task.
The challenges are even more daunting because the tanks are buried uder 7-10 feet of soil and were made to put waste in, not take it out. Access to the tanks is limited and all work must be done by remote control. When the cleanup of Hanford began in 1989 the technology to remove waste from the tanks did not exist. Those technologies were pioneered at Hanford and the development of new techniques and technologies continues today as we improve our understanding of the waste.
