1. = The isotope 1251 is produced in a nuclear reactor by irradiation of isotope 124 Xe (o = 148 b), which is converted to isotope 125Xe (t1/2 = 19.9 h) by neutron capture. Isotope 125Xe decays into isotope 125I (t1/2 = 59.49 days). The scheme of the reaction chain is presented below. How much isotope 125Xe and 1251 is produced in a nuclear reactor with neutron flux of 1013 cm ?s?, if we irradiate 1 kg of isotope 124 Xe for 3 days? How many atoms of isotope 1251 decay during irradiation in the reactor? After irradiation all of 1251 is removed from the irradiated material and placed under a detector with 100 % efficiency. How long do we need to measure to detect 1018 decays? o = 148 b 01/2= 19.9 h (124 t12= 59.49 d 125 125