Actinide Elemental Ratios of Spent Nuclear Fuel Samples\nby Resonance Ionization Mass Spectrometry

While\nresonance ionization mass spectrometry (RIMS) has demonstrated\nutility in measuring isotopic compositions of elements in complex\nmatrices without the need for chemical separation to remove isobaric\ninterferences, it has had limited application in measuring elemental\ncompositions. The ability to determine elemental compositions via\nan in situ method like RIMS would be an exceptional asset in spent\nnuclear fuel analysis, where they are important in assessing reactor\nhistories and whose chemical separation presents a radiological hazard.\nHowever, quantitative elemental analysis by RIMS requires special\nconsiderations because each element is ionized by its own set of lasers\ntuned to element specific resonant ionization wavelengths. We present\nthe first comprehensive study of measuring elemental ratios by RIMS\nin spent nuclear fuel. All actinides produced by neutron capture are\nenhanced significantly radially from the center to the edge of a fuel\npellet. This edge effect is not readily accessible by conventional\nbulk measurements.