Calculation and experimental validation of ¹²⁷I transmutation rate in Xi'an pulsed reactor

In order to develop the research on ¹²⁹I transmutation in the thermal reactor, ¹²⁷I target was irradiated in Xi'an pulsed reactor(XAPR) to explore the condition for experiment in XAPR. The Monte Carlo method was used in the calculation of ¹²⁷I target transmutation rate, and the results were compared with the experimental data. The NJOY software was used to generate ¹²⁷I ace format neutron cross section at XAPR operating temperature based on ENDF/B VII.0 library. New cross section was compared with old ENDF/B VI library and developed in the unresolved resonance region. MCNP was used to modify the ¹²⁷I cross section of ORIGEN2 by adopting a new cross section, then transmutation of ¹²⁷I target was calculated to analyze changes of transmutation rate and nuclides, also the influence of neutron spectrum and irradiating time on transmutation was studied. The CINDER'90 software, a depletion mode of MCNPX, was also used to model the transmutation condition, the analytical result was consistent with ORIGEN2, but was a little different from the experimental data (2%-3% error) because of the deviation from the MCNP model in neutron flux calculation. (authors)