Organic Analyses of Highly Radioactive Solutions Requiring Pretreatment by ¹³⁷Cs Removal

Abstract

The beta-emitting radionuclide ¹³⁷Cs is precipitated from the Savannah River Site (SRS) high-level waste by adding sodium tetraphenylborate (TPB). The concentrated and washed precipitate slurry containing CsTPB is transferred to Defense Waste Processing Facility (DWPF) Salt Processing Cell and hydrolyzed to yield an aqueous product (PHA) free of benzene. The PHA is highly radioactive (1E+11 dpm) and contains some water-soluble organic compounds that need to be analyzed for process control and process history. High performance liquid chromatography (HPLC) methods were developed to analyze these compounds with instruments contained in unshielded fume hoods. Removing ¹³⁷Cs from PHA in a shielded cell prior to HPLC analyses is essential to minimize personnel radiation exposure. In this study ammonium molybdophosphate (Bio-Rad AMP-1) was used for removing ¹³⁷Cs in PHA (pH 3.8). With a two-step application of AMP slurry, a decontamination factor of 1E+4 was achieved for Cs removal. Two separate HPLC methods were used to analyze four polar organic compounds. The recovery of all the organic compounds were above 85%.