DIRECT-SCANNING ALPHA-SPECTROMETER FOR AMERICIUM AND PLUTONIUM CONTAMINATION ON HIGHLY-ENRICHED URANIUM SURFACES

Trace Pu-239 and Am-241 contamination on a surface whose alpha count i s dominated by U-235 and U-234 decay has been successfully quantified by counting swipes in external alpha-spectroscopy chambers. The swipe process, however, is labor intensive and subject to uncertainties in t he swiping process as well as degraded spectral resolution due to the presence of the swipe material. A multichannel instrument for automate d in situ measurements of interior and exterior contamination has been developed which incorporates a rotary table, 13 fixed ion-implanted s ilicon detectors, and spectroscopy electronics. Custom software was wr itten to allow alpha-spectrometer to function as a virtual instrument in the LabView environment. This system gives improved speed and resol ution as well as a complete log of the location of areas of high surfa ce contamination, a feature not practical to obtain by other methods, and one which opens the possibility of long term studies such as Pu ou tgrowth evaluation employing the instrument. We present performance da ta as well as system integration, calibration, control and dynamic geo metric efficiency calculations related to the design of this and next generation systems.