CHARACTERIZATION OF SPENT NUCLEAR-FUEL DISSOLVER SOLUTIONS AND DISSOLUTION RESIDUES BY INDUCTIVELY COUPLED PLASMA MASS-SPECTROMETRY

The direct analysis of dissolved spent nuclear fuel by inductively coupled plasma mass spectrometry (ICP-MS) allows the elemental and isotopic composition of the irradiated fuel to be determined-without any chemical separation. A qualitative evaluation was carried out on the effects of fission, beta-decay and neutron-capture reactions during fuel irradiation. Semiquantitative analysis of fission products and actinides in the spent-fuel dissolver solution and in the dissolved residues was performed by referring to a response curve. Comparison of the semiquantitative data with computer predictions of fission products inventory showed satisfactory agreement. The analysis of small spent fuel samples by ICP-MS was used to assess the type and irradiation of the fuel in pattern recognition studies. Quantitative analysis of the fuel solutions and residues was performed only for selected elements because of the presence of isobaric interferences Isotope dilution analysis was applied for polysotopic elements; standard additions with an internal standard was used for monoisotopic elements. Elements determined in the residues included Zr, Mo, Tc, Ru, Rh Pd, U and Pu. Neodymium was also determined in dissolver solutions of fast neutron-irradiated fuels and the results were compared with those given by thermal ionization mass spectrometry.