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Synthesis and evaluation of an inorganic microsphere composite for the selective removal of {esc}p137{esc}scesium from acidic nuclear waste solutions /by Troy J. Tranter.

Authors
Publication Date
Keywords
  • Inorganic Ion Exchange Materials--Design.
  • Radioactive Waste Disposal.
  • Cesium--Separation.
  • Ammonium Compounds.
  • Molybdenum Compounds.
Disciplines
  • Design
  • Medicine

Abstract

This work describes the results of a multi-year research and development effort to produce an inorganic ion exchange material for removing {esc}p137{esc}s Cs from acidic nuclear waste solutions. Various quantities of this waste exist throughout the United States, France, and Russia as a legacy of decades of nuclear fuel reprocessing and nuclear weapons production. For example, the Idaho National Laboratory (INL) currently stores about 900,000 gallons of acidic, high-level radioactive waste stemming from the various solvent decontamination processes associated with the reprocessing of naval reactor fuel assemblies. Internationally, the planned disposition path for these waste streams is solidification followed by storage in a geological repository. Since {esc}p137{esc}s Cs is a primary contributor to heat load and radiological dose, most treatment schemes involve removing this isotope from the bulk waste in order to facilitate handling and storage. However, since these liquid waste streams are highly acidic and ionic, they become problematic for any type of separation process. Consequently, an adsorbent or ion exchange material designed for use with these waste streams must be unique, having exceptional selectivity and stability in high radiation, temperature, and acid environments.;As result of this research effort, a new inorganic ion exchange composite consisting of ammonium molybdophosphate, (NH{esc}b4{esc}s){esc}b3{esc}sP(Mo{esc}b3{esc}sO{esc}b10{esc}s){esc}b4{esc}s*3H{esc}b2{esc}sO(AMP), synthesized within hollow aluminosilicate microspheres (AMP-C) has been produced. The selective cesium exchange capacity of this inorganic composite was evaluated using simulated sodium bearing waste solution as a surrogate for the tank waste currently stored at the INL. Equilibrium isotherms obtained from these experiments were very favorable for cesium uptake and indicated maximum cesium loading of approximately 9 % by weight of dry AMP. Column tests were performed using bench-scale columns and complete breakthrough curves were obtained from these tests. The dynamic capacity of the columns was determined to be approximately 2.5 g Cs/kg exchanger (18.8 millimole/kg) for the feed concentrations of interest.

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