Thermal-Neutron Radiography with a Sealed-Tube Neutron Generator and Water Moderator

Neutron radiography studies have been conducted using an accelerator source of 14.3 ± 0.3 MeV neutrons and a water moderator. The yield of the accelerator was 6.18 × 10¹ n/sec. The peak thermal-neutron flux of the system was measured to be 6.87 × 10⁷ n/(cm² sec) at 5.1 cm from the source. A cadmium ratio of 3.4 was measured at this position. A theoretical two-group analysis of the thermal-neutron flux distribution was also performed. The experimental data verified the theoretical results. Neutron multiplication experiments were also conducted by bombarding a ²³⁸U target surrounded by the water moderator. It was experimentally determined that 2.5 cm of ²³⁸U yielded a maximum multiplication factor of 2.5.