Neutron flux determination in irradiation sites of an Am–Be neutron source at NNRI

Neutron flux measurements and flux distribution parameters for two irradiation sites of an Am–Be neutron source irradiator were measured by using gold (Au), zirconium (Zr) and aluminum (Al) foils. thermal neutron flux Φth = 1.46 × 104 n cm−2 s−1 ± 0.01 × 102, epithermal neutron flux Φepi = 7.23 × 102 n cm−2 s−1 ± 0.001, fast neutron flux Φf = 1.26 × 102 n cm−2 s−1 ± 0.020, thermal-to-epithermal flux ratio f = 20.5 ± 0.36 and epithermal neutron shaping factor α = −0.239 ± 0.003 were found for irradiation Site-1; while the thermal neutron flux Φth = 4.45 × 103 n cm−2 s−1 ± 0.06, the epithermal neutron Φepi = 1.50 × 102 n cm−2 s1 ± 0.003, the fast neutron flux Φf = 1.17 × 10 n cm−2 s−1 ± 0.011, thermal-to-epithermal flux ratio f = 29.6 ± 0.94, and epithermal neutron shaping factor α = 0.134 ± 0.001 were found for irradiation Site-2. It was concluded that the Am–Be neutron source can be used for neutron activation analysis (NAA). The Am–Be source can be used for neutron activation analysis thereby reducing the burden on GHARR-1 and increasing the research output of the nation.

► Neutron flux distribution of two sites of an Am–Be neutron source was determined.
► Neutron shaping factor α = −0.239 ± 0.003 was found for Site-1.
► Neutron shaping factor α = 0.134 ± 0.001 was found for Site-2.
► Thermal-to-epithermal flux ratio f = 20.5 ± 0.36.
► Thermal-to-epithermal flux ratio f = 29.6 ± 0.94.