Neutronics calculations for the assessment of proliferation risks associated with spallation neutron sources

A parametric study has been performed to estimate potential proliferation risks associated with spallation neutron sources and to give first hints for indicators, if and when nonproliferation measures (technical, political) have to be considered. To this end calculations with the Monte Carlo transport code MCNPX were performed. A maximum scenario and more realistic simple cylindrical geometries were calculated. They show that even with moderate accelerator parameters (approx. 300 MeV, 1–2 mA) a sensitive production of 0.5 kg Pu 239 per year available beam time can be obtained by simply bombarding uranium with protons. Even better designs are conceivable. These calculations were supplemented with the investigation of more realistic production scenarios, some of which were calculated in more detail.