Comparison of analysis results of SNM measurements by means of device implemented automatic analysis routines, FRAM and MGA/MGAU

The possibility of radioactive or nuclear material falling into the wrong hands poses a serious threat to society. When thinking of such context in the case of a finding of suspicious objects it is necessary to gain information about those materials. Especially in the case of nuclear material involved there is a need to identify and classify the material. In a previous paper, measurements of nuclear material using portable high energy resolution detection systems were presented. These systems use electrical cooling and implemented automatic analysis routines. The focus in the earlier presented results had been the outcome of these automatically evaluated results. Four different detectors were investigated: the FALCON 5000 from Canberra and three out of the Detective family from ORTEC (Detective EX, Micro-Detective and Detective 200). The latter differ partly in the hardware (e.g. size of Ge-crystal) and the version of the automatic analysis routine. The Micro-Detective and Detective 200 - in contrary to the two other devices - do not categorize the degree of enrichment or isotopic composition in general. This paper addresses the results of the analysis of the obtained spectra using Isotopic Analysis Software FRAM and Multi Group Analysis MGA/MGAU as well as a comparison to the results of the implemented analysis routines. It will be shown, that the analysis using the separate analysis software leads to enhanced results. Analysis limitations of FRAM and MGA/MGAU are figured out. The results indicate that FRAM leads to more reliable results. It enables the analysis of a larger number of spectra. In general both analysis programs lead to better results than the automatic analysis routines. Partly results concerning the isotopic composition can only be obtained by these programs. The paper gives an overview of the results obtained for shielded and unshielded nuclear material measured with the different detectors. In total eight uranium and plutonium sources with different enrichment respectively composition were measured. The measurements took place at the Institute for Transuranium Elements (ITU) at the Joint Research Center (JRC) in Karlsruhe, Germany.