Neutron streaming experiment for radiation shielding hatch by ²⁵²Cf source

Nuclear facilities with strong radioactivity need massive concrete shields. In the view of shielding design, there arise some difficulties in the estimation of radiation doses from a gap or a void between the hatch and the wall. So, there is a need of experimental data and calculational procedures on such geometry for a reasonable shielding design. The experiments were carried out by ^252Cf neutron source. A gap between the shielding hatch and the wall, and the offset of the shielding hatch were simulated by piling up the concrete slabs to the height of 30 cm. The thickness of the slabs are 10 cm each. Neutron dose was measured by REM-counter and CR-39 plate. To simulate various types of the shielding hatch, gap width and offset length of each gap were changed. Results of the experiments shows that the dose rate goes up with increment of gap width when the offset was fixed. The experimental data were also compared with the calculations by MCNP4B. We obtain the guide of design for radiation shielding hatch. (author)