The production of Na24 in a body by neutron irradiation is an important part of a system of monitoring nuclear accidents. The feasibility of using phantoms filled with a homogeneous aqueous solution of NaCl in the determination of the relationship between neutron dose and Na24 production was investigated using phantoms, burros and the LASL Godiva II and ORNL Tower Shielding Facility II reactors. The Na24 production per unit neutron dose was measured in man-shaped phantoms, cylinders and burros. It was found that: (1) the ratio of the concentrations of Na24 and Na23, (Na24/Na23), in circulated blood is equal to the ratio in the whole body; (2) the inhomogeneity of the distribution of Na in living animals is not significant in the production of Na24; (3) a phantom filled with NaCl solution can be used to approximate a living animal in experiments involving the production of Na24 by neutron irradiation; (4) the size of a body and its orientation with respect to the source of neutrons has an effect on the magnitude of the Na24 production; and (5) if analyses of blood samples are used to determine Na24 production in the burro, the exact time of sampling, within the range of 2–24 hrs post-irradiation, is not important.
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