Determination of neutron temperature in irradiation channels of reactor

In situ measurement of neutron temperature for the extended k0 NAA at FRM II

The neutron temperature at different irradiation positions in the research reactor FRM II was measured using thermometer labels together with lutetium standards. This was the first time to measure the local temperature at the irradiation positions with this combination. The simplified Westcott formalism was used to calculate the neutron temperature using Lu and g(Tn) factors from different data sources. The results showed agreement between neutron temperature according to the Lu method and the temperature showed on the labels. They can be used as a reliable alternative to determine the neutron temperature instead of using Lu standards in the extended k0 NAA.

Determination of neutron flux parameters (f, α, φth and φe) 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_th, φ_e, 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_th, φ_e, f [f_bare] 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 φ_th and f values correspond with those measured during the first startup of the reactor; the values of φ_th are more reliable than φ_e,-values, as are the inner site's f and α results in comparison with outer site's values; the inner site's φ_th and φ_e 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.