PLUTONIUM SOURCE ISOTOPIC ANALYSIS WITH UP TO 25- MM LEAD SHIELDING USING THE FRAM ISOTOPIC ANALYSIS CODE

The FRAM Isotopics Analysis Code has been used to analyze plutonium spectra taken through very thick shielding. Three plutonium sources with 240Pu content of 6.6%, 9.7%, and 16.3% were measured with lead shielding levels ranging from zero to 21.9 mm, in nominal increments of 1.6 mm. Multiple spectra were taken for each sample at each shielding level, and the spectra were analyzed using FRAM V3.2. The standard shielded coaxial detector parameter set was used up to approximately 10-mm-thick-lead. A new parameter set was developed to analyze spectra from 0 to 25-mm-thick lead. We will report on the accuracy capabilities of this parameter set. (LA-UR-00-129)