RADIOLYSIS AND HYDROLYSIS OF MAGNETICALLY ASSISTED CHEMICAL-SEPARATION PARTICLES

The magnetically assisted chemical separation process is designed to s eparate transuranic (TRU) elements from high-level waste or TRU waste. Magnetic microparticles (1-25 mu m) were coated with octyl (phenyl)-N ,N-diisobutylcarbamoyl-methylphosphine oxide dissolved in tributyl pho sphate and tested for removing TRU elements from acidic nitrate soluti ons. The particles were contacted with nitric acid solutions or simula ted Hanford Plutonium Finishing Plant waste solution, irradiated with a high intensity Co-60 gamma-ray source, and evaluated for their effec tiveness in removing TRU elements from 2 M HNO3 solutions. The resista nce of the coatings and magnetic cores to radiolytic damage and hydrol ytic degradation was investigated by irradiating samples of particles suspended in a variety of solutions with doses of up to 5 Mrad. Transm ission electron microscopy, magnetic susceptibility measurements, and physical observations of the particles and suspension solutions were u sed to assess physical changes to the particles. Processes that affect the surface of the particles were found to dramatically alter the bin ding sites for TRU in solution. Hydrolysis played a larger role than r adiolysis in the degradation of the extraction capacity of the particl es.