抄録
The primary feature of the environmental impact by the JCO criticality accident was that neutrons were the main contributor of its radiological consequences. We continue the efforts to reconstruct the behavior of neutrons in the environment around the JCO facilities, using three dimensional Monte Carlo transport codes (MORSE, MCNP) and two dimensional Sn transport code (DOT3.5). The geometry inside the JCO territory was modeled with a cluster of 8 buildings including the Uranium Conversion Testing Building (UCTB) where the criticality accident took place. Neutron dose and neutron-induced activities (Co58, Cr51, Co60 etc.) have been calculated around the JCO territory and compared with measured values. So far, we succeeded in reconstructing neutron doses at 13 monitoring points along the JCO territory (70 - 540 m from UCTB) within the maximum deviation of 40% from measurements. Self-shielding of sampled materials and shielding effects of houses are being calculated using forward-adjoint coupling technique. We will evaluate neutron spectrum and neutron dose inside houses. [J Radiat Res 44:420 (2003)]
