SEPARATION OF TRANSMUTATION- AND FISSION-PRODUCED RADIOISOTOPES FROM IRRADIATED BERYLLIUM

摘要

The primary objective of this study was to test the effectiveness of a two-step solvent extraction-precipitation process for separating transmutation and fission products from irradiated beryllium. Beryllium metal was dissolved in nitric and fluoroboric acids. Isotopes of ~(241)Am, ~(239)Pu, ~(85)Sr, ~(60)Co, and ~(137)Cs were then added to make a surrogate beryllium waste solution. A series of batch contacts was performed with the spiked simulant using chlorinated cobalt dicarbollide and polyethylene glycol diluted with sulfone to extract the isotopes of Cs and Sr. Another series of batch contacts was performed using a combination of octyl (phenyl)-N,N- diisobutylcarbamoylmethylphosphine oxide in tributyl phosphate diluted with dodecane for extracting the isotopes of Pu and Am. The ~(60)Co was separated by first forming a cobalt complex and then selectively precipitating the beryllium as a hydroxide. The results indicate that >99.9% removal can be achieved for each radio-nuclide. Transuranic isotope contamination levels are reduced to <100 nCi/g, and sources of high beta-gamma radiation (~(60)Co, ~(137)Cs, and ~(90)Sr) are reduced to levels that will allow the beryllium to be contact handled. The separation process may be applicable to a recycle or waste disposition scenario.