Separation of lanthanides for isotopic analysis to determine neutron environment in fission reactors

The measurement of lanthanide isotopic ratios present in spent nuclear fuel can give information on conditions within a reactor. The reactor environment alters these ratios via two processes: fission production and neutron absorption. Determining such ratios requires a combination of chemical separation, via column chromatography, and analysis with multiple-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). Separation of neodymium involves two columns, cation exchange followed by LN Resin using HCl as the eluant, with MC-ICP-MS providing measurements with ppm precision. Extending the separation to the heavier lanthanides will involve the same columns but will require HCl and alpha-hydroxyisobutyric acid (α-HIBA) as eluants. Based on previous studies α-HIBA will be used with LN resin columns as well as bis-(2-ethylhexyl) phosphoric acid (HDEHP) coated HPLC columns.