Determination of neutron flux parameters (f, α, φ and φ) of the irradiation sites of Isfahan MNSR reactor using empirical and MCNPX2.6 simulation approaches.

Miniature Neutron Source reactors (MNSRs) are ideal for applications such as nuclear research, neutron activation analysis, etc., provided that their neutron flux parameters (φ, φ, f and α) are known. This paper present the results of the neutron flux parameters at inner and outer irradiation sites of Isfahan MNSR reactor determined through simulation with MCNPX2.6 code and experimentally using bare and cadmium-covered gold foils irradiation and bare triple (AuZr) monitor methods. In empirical approach, the obtained φ, φ, f [f] and α-values were 5.02 × 10 ncms (±4.5%), 3.13 × 10 ncms (±2.3%), 16.0 (±6.7%) [17.3 (±9.9%)] and -0.121 (±0.2%), for inner site; and 2.93 × 10 ncms (±2.3%), 6.48 × 10 ncms (±3.1%), 45.2 (±5.4%) [42.5 (±7.1%)] and -0.011 (±1.8%), respectively, for outer site. In simulation approach, while, they were found to be 4.76 × 10 ncms (±0.9%), 2.00 × 10 ncms (±2.2%), 23.8 (±3.1%) and -0.078 (±0.13%), for the inner site; and 2.67 × 10 ncms (±1.1%), 3.79 × 10 ncms (±5.4%), 70.4 (±6.5%) and -0.017 (±0.4%) for the outer site, respectively. Comparison of empirical and simulation results clearly revealed that: the inner site's φ and f values correspond with those measured during the first startup of the reactor; the values of φ are more reliable than φ,-values, as are the inner site's f and α results in comparison with outer site's values; the inner site's φ and φ are ∼1.7 and 5 times, respectively, larger than those of outer site; and the inner site 's α and f-values are more than 4.8 and 2.4 times larger and less than the outer site's values, respectively.