The goal of this work was to determine the effects on plutonium isotopic analysis of having plutonium inside of a 0.25 inch thick stainless steel can. To do this, they analyzed plutonium samples with a U-Pu InSpector (which uses a high-resolution gamma-ray detector and the analysis code MGA (Multi Group Analysis)), to determine both the 240-Pu/239-Pu ratio and the years since the plutonium was separated from americium. They analyzed a 1.6 kg plutonium sample that was placed inside of a 0.25 inch can at varying distances (0-2 meters) and count times (10 seconds-30 minutes). In separate experiments, they analyzed 0.4g plutonium sources with stainless-steel thickness' ranging from 0.125 to 1.0 inch. This report will show three effects of having plutonium in a stainless steel can: (1) 240-Pu/240-Pu can be quickly and accurately determined for a 1.6 kg plutonium sample inside of a 0.25 inch thick stainless-steel can, as this thickness of stainless steel acts as a perfect filter to reduce the intense 59 keV gamma peak from 241-Am. (2) The accuracy of determining the plutonium-americium separation date is not effected by 0.25 inch of stainless steel. (3) Both 240-Pu/239-Pu and the americium separation date can be accurately determined for stainless-steel thickness' up to 0.5 inches, requiring additional counting time with increasing thickness to obtain desired precision. For stainless-steel absorber thickness' greater than 0.5 inch, MGA analyses are not reliable.
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