FRAM’s Isotopic Uncertainty Analysis

摘要

The Fixed-Energy Response-Function Analysis with Multiple Efficiency (FRAM) code wasrndeveloped at Los Alamos National Laboratory to measure the gamma-ray spectrometry of thernisotopic composition of plutonium, uranium, and other actinides. We have studied and identifiedrntwo different kinds of errors from FRAM analysis: random and systematic. The random errorsrncome mainly from statistics and are easily determined. The systematic errors can come from arnvariety of sources and can be very difficult to determine.rnWe carefully examined the FRAM analytical results of the archival plutonium data and of therndata specifically acquired for this isotopic uncertainty analysis project, and found the relationshiprnbetween the systematic errors and other parameters. We determined that the FRAM’s systematicrnerrors could be expressed as functions of the peak resolution and shape, region of analysis, andrnburnup (for plutonium) or enrichment (for uranium). All other parameters such as weight, matrixrnmaterial, shape, size, container, electronics, detector, input rate, etc., contribute little to thernsystematic error or they contribute to the peak resolution and shape and then their contributionsrncan be determined from the peak resolution and shape.