Back End of the Cold War

Paul Bredt, PhD
Division Director of the Nuclear Sciences Division, Energy and Environment Directorate, Pacific Northwest National Laboratory

Founded as part of the Manhattan Project, the Hanford Site in southeastern Washington State was critical to the production and purification of 67 metric tons of plutonium for national defense.  While production ceased in 1990, there is still a sizable cleanup mission ahead.  Hundreds of billions of gallons of liquid were discharged to the ground, leaving contaminated soil and groundwater, and highly contaminated production facilities must be maintained in safe configurations pending final closure. In addition, approximately 200 million liters of highly radioactive slurries are stored in 177 aging underground tanks.  This tank waste is one of the most serious challenges on the site. The Department of Energy (DOE) is constructing the Hanford Waste Treatment Plant to convert this waste into recalcitrant solid wasteforms.  With an approximate 40-year mission and construction and operating costs estimated at $300 billion, it is one of the largest financial liabilities of the United States government. However, the sheer volume and hazard, complexity and continually evolving chemistry, stakeholder expectations, nuclear construction standards, and aging of the tanks themselves have all conspired to delay construction and drive DOE to rethink the treatment baseline.

Scientists and engineers at what is now Pacific Northwest National Laboratory (PNNL) were instrumental in the design and operation of facilities that generated these wastes, have developed most of the unit operations planned for the Hanford Waste Treatment Plant, and will be supporting operations through the treatment mission.  This presentation will include a history of the Hanford site, the baseline flowsheet and alternatives under consideration for tank waste treatment, as well as a brief summary of PNNL.