Dennis Benker

Separation of Americium, Curium, and Plutonium from Irradiated Targets

Abstract The Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory (ORNL) processes highly irradiated targets for the Mark 42 program to separate Am, Cm, and Pu. The target feed material for each assembly was 3.3 kg of plutonium (78% 239Pu) that was irradiated at the Savannah River Site to yield approximately 100 g each of 243Am and 244Cm, and 100-g quantities of 242Pu for special DOE projects. The REDC has plans to process ten of these target assemblies over the next few years. The first assembly has been dissolved, and approximately 1/4 of this material has been used to test the processing flowsheet. Various aqueous processes developed at the REDC over the past years were utilized to dissolve the target segments, separate the bulk of the impurities from the transuranics, separate the plutonium from the transplutonium actinides, and separate the rare earth fission products from the Am-Cm. The separation of the Am-Cm products to the desired purity levels presented new proces...

Reestablishing the Supply of Plutonium-238

The US Department of Energy has presented a plan to use existing reactors at Oak Ridge National Laboratory (ORNL) and Idaho National Laboratory (INL) and processing facilities at ORNL, modified as needed, to produce Pu. The basic capabilities that need to be put into place to produce new Pu are (1) neptunium storage and transport, (2) target fabrication, (3) target irradiation, and (4) chemical processing of irradiated targets to recover Pu. Neptunium currently in storage at INL will be shipped to ORNL during CY 2015. The target design has progressed to a prototypic target design that is expected to be used for production. Initial chemical processing experiments have shown successful recovery of neptunium and plutonium, but overall product purity has not been as high as desired.

Dissolution and Separation of Aluminum and Aluminosilicates

Selection of an aluminum alloy for target cladding affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the dissolver, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. Aluminosilicate dissolution presents challenges in a number of different areas, including metals extraction from minerals, flyash treatment, and separations from aluminum alloys. We present experimental work that attempts to maximize dissolution of aluminum metal in caustic, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as a function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. These data have been compared with published calculations of aluminum phase diagrams. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.

Aluminum Target Dissolution in Support of the Pu-238 Program

Selection of an aluminum alloy for target cladding affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the caustic dissolution step, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. We present a study to maximize dissolution of aluminum metal alloy, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as a function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. These data have been compared with published calculations of aluminum phase diagrams. Temperature logging during the transients has been investigated as a means to generate kinetic and mass transport data on the dissolution process. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.