Determination of neutron flux parameters (f, [formula omitted], φth and φe) of the irradiation sites of Isfahan MNSR reactor using empirical and MCNPX2.6 simulation approaches

Abstract

Miniature Neutron Source reactors (MNSRs) are ideal for applications such as nuclear research, neutron activation analysis, etc., provided that their neutron flux parameters (φth, φe, 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 φth, φe, f [fbare] and α-values were 5.02 × 1011 ncm−2s−1 (±4.5%), 3.13 × 1010 ncm−2s−1 (±2.3%), 16.0 (±6.7%) [17.3 (±9.9%)] and −0.121 (±0.2%), for inner site; and 2.93 × 1011 ncm−2s−1 (±2.3%), 6.48 × 109 ncm−2s−1 (±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 × 1011 ncm−2s−1 (±0.9%), 2.00 × 1010 ncm−2s−1 (±2.2%), 23.8 (±3.1%) and −0.078 (±0.13%), for the inner site; and 2.67 × 1011 ncm−2s−1 (±1.1%), 3.79 × 109 ncm−2s−1 (±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 φth and f values correspond with those measured during the first startup of the reactor; the values of φth are more reliable than φe,-values, as are the inner site's f and α results in comparison with outer site's values; the inner site's φth and φe 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.