Ore samples (autunite, ningyoite, pitchblende) were sequentially leached in hydrochloric acid and nitric acid, and the concentrations of radioactive nuclides and stable elements in the leachates were measured to determine the leaching fractions of nuclides and the activity ratios between nuclides. Uranium and thorium were leachable in hydrochloric acid and nitric acid, respectively. The activity ratios of234U/238U 230Th/238U, and226Ra/238U in the leachates were higher than those in the bulk. The leaching effect of nuclides was enhanced as the number of alpha-decay was increasing. The damages due to alpha-recoil nuclides having a longer half-life were self annealed, decreasing the leaching effect of these nuclides.
We have studied the formulation of skeletal substitutes for an in vivo calibration phantom using the basic data method introduced by White. An equation for calculating the optimum relative mass of corrective additives was developed. Also, epoxy resin based tissue substitutes simulating the skeleton, cortical and trabecular bones were developed. The substitutes were examined for the photon transmissions using 16.6 keV KX-rays from93mNb and 59.5 keV gamma rays from241Am. It was found that the experimental transmission curves of the substitutes are in good agreement with the calculated ones. The equation for the corrective additives was validated. The skeletal substitutes were found to be suitable as the corresponding tissues defined in ICRP Publication 23.
Since the dose conversion factor (hereafter called DCF) due to radon progeny inhalation is strongly dominated by aerosol characteristics in the environment, it is important to understand the air quality for accurate dose assessment. Thus temporal variations on aerosol concentration, its particle size and its related airborne radioactivities were continuously measured in an actual indoor environment with a relatively high radon concentration. The following human activities were added during the observation period : air-conditioning, removal of aerosol with an air cleaner and ventilation. DCFs based on these activities were evaluated with the latest ICRP respiratory tract model and were compared among them. Consequently, the present study has shown that operation of air cleaner enhanced the DCF critically because the unattached fraction increased significantly due to removal of aerosols.