Direct measurement of actinides in liquids with PIPS diodes


R. Shane Addleman1, Oleg B. Egorov2, Matt O'Hara2, and Jay Grate2. (1) Environmental Technology Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, (2) Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352
The determination of actinides in nuclear wastes, process solutions and various other liquid matrices is required in support of environmental restoration and waste processing activities. We will show that passivated implanted planar silicon (PIPS) diodes can provide rapid direct actinide assay of high level solutions without human exposure or waste generation issues. For low activity samples we will demonstrate direct isotopic assay of liquids for actinides with polymer membrane modified PIPS diodes. This synergistic combination of a chemically selective polymer film that concentrates ions of interest upon the diode surface and the spectral energy resolution available from the PIPS detector enables excellent isotopic selectivity and sensitivity. With thin films we have obtained high resolution alpha energy spectra directly from solution. Further, by using plasticizers that are also strong complexants, we have been able to selectively concentrate the actinides upon the diode surface resulting in a significant increase in sensitivity relative to direct analysis.