Examination for Neutron Dose Assessment Method from Induced Sodium-24 in Human Body in Criticality Accidents

概要

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Experiments were made to verify a dose assessment method from activated sodium in human body in criticality accidents. A slab phantom containing sodium chloride solution was irradiated in the Transient Experiment Critical Facility to simulate activation of sodium in body. Monte Carlo calculations were performed to obtain quantitative relation between the specific activity of induced 24Na and neutron dose, which was imparted by charged particles liberated by neutrons, at the phantom position. In the previous work, conversion coefficients from specific activity of 24Na in soft tissue to whole body dose had been analyzed with the MCNP-4B code concerning neutron spectra at some hypothesized configurations with fuel and surrounding materials. One of the prepared conversion coefficients was applied to evaluate neutron dose from the measured radioactivity of 24Na. The estimated dose agreed with the dose analyzed by the Monte Carlo calculations in the present study within an acceptable uncertainty for initial dose determination in an accident, which is indicated by the International Atomic Energy Agency. In addition, the dose assessed with the prepared coefficient from the quantity of induced 24Na was close to a value, which had been previously measured with dosimeters for criticality accidents.
社団法人日本原子力学会の論文
2005-04-25