MGAU results of mine samples containing considerable quantities of ~(226)Ra, ~(232)Th and minute amounts of natural Uranium

摘要

In nuclear safeguards it is required that enrichment levels of safeguarded material be quantified and declared as appropriate to the International Atomic Energy Agency (IAEA). Usually these enrichment levels are determined using the Multi Group Analysis of Uranium (MGAU) code by States and the IAEA. It is known that MGAU earlier versions up to version 4.2, provide erroneous enrichment results for uranium samples containing considerable amounts of ~(232)Th. This led to the updated MGAU version 4.3 which showed huge improvement by providing correct results. In this study soil samples were collected for measurements using high purity germanium detector system from various areas in a Copper mine that also produce uranium as a byproduct. Spectra collected from these samples showed peaks predominantly from ~(226)Ra and ~(232)Th while Destructive Analysis results confirmed the presence of relatively minute amounts of natural uranium. These spectra were analysed using MGAU version 4.2 which provided enrichment results which incorrectly suggested that the material is Low Enriched Uranium (LEU).It is therefore noted that such material may be mistaken for LEU material which may results in erroneous declarations to the IAEA by States that may happen to possess it. It would also be interesting to analyse these spectra using the updated version 4.3 of MGAU to see what results could be obtained.