Nuclear Material Verification Based on MCNP and ISOCSTM Techniques for Safeguard Purposes

Abstract

Recently, Mathematical techniques such as Monte Carlo and ISOCS software are being increasingly employed in the absolute efficiency calibration of gamma ray detector. Monte Carlo simulations and Canberra ISOCS TM software bring the possibility to establish absolute efficiency curve for desired energy range based on numerical simulation, with use of known or guessed geometry and chemical composition, of measured item. Broad-energy germanium (BEGe) detector was employed to perform the NDA measurements to five standard reference nuclear material (NBS, SNM-969). MC calculations were performed to calculate some factors (attenuation, geometry and efficiency) which affect the uranium isotope mass estimation. 235 U and 238 U masses are calculated based on MCNPX modeling calibration and also upon spectra analysis using ISOCS TM Calibration Software. The obtained results from the two different efficiency calibration methods were compared with each other and with the declared value for each sample. The obtained results are in agreements with the declared values within the estimated relative accuracy (ranges between -2.81 to 1.83%). The obtained results indicate that the techniques could be applied for the purposes of NM verification and characterization where closely matching NM standards are not available.