Low energy beta-ray emitters in air can be measured efficiently using a foggy scintillator. By operation of an ultrasonic wave generator, a liquid scintillator can be changed into the foggy scintillator. In order to enhance the counting efficiency, it is necessary to prepare a liquid scintillator with very high concentration of first solute (PPO) . This system can eliminate the troublesome of the sample preparation for the measurements of radioactive nuclide in air, since the activity concentration in air can be measured directly. Detection limits of3H were estimated roughly to be 1.5×10-3 Bq/mL for the measurement of 10 min.
With the increasing uses of electric and electronic devices in space and nuclear power stations, those organic insulation materials are inevitably exposed to various kinds of environments. Accordingly, it becomes necessary to investigate the influence of the pressure and radiation on insulation materials. The total dose of gamma-ray irradiation effects on the erosion depth and discharge quantity have been studied. The experiment was carried out by DC impulse voltage under reduced pressure. Polybutylene naphthalate, which was irradiated in air up to 100 kGy and 1 MGy with dose rate of 10 kGy/h using a60Co gamma-source, has been used as the test sample. The changes of erosion depth and discharge quantity are discussed with decreasing the atmospheric pressure in the range from 100 kPa to 0 kPa and the frequency of applied impulse voltage in the range from 100 Hz to 200 Hz. It is found that the both of the erosion depth and discharge quantity decreased with increasing the total dose of gamma-ray irradiation and decreasing the atmospheric pressure, and increased with increasing the frequency of applied impulse voltage.
A large quantity of131I has been widely used for the treatment of thyroid cancer with progress of nuclear medicine, and it gives a burden to facilities for treatment of the liquid waste containing131I. For the purpose of advanced treatment of liquid waste containing131I and minimization of the burden of the facilities, iodine removal methods by ionexchange resin or activated carbon were attempted, however, it was found to be difficult to remove iodine from the liquid waste by these adsorbents. This report describes the application of the activated carbon impregnating per-bromine ion with abilities of organic iodine removal by halogen substitution reaction in gas phase and organic solvent phase. Removal experiments using the impregnated carbon towards several kinds of solution containing iodine were attempted. Removal efficiencies of the impregnated carbon become apparent as bellow. •Higher removal efficiency and adsorption capacity were obtained by the impregnated carbon impregnating higher ratio of per-bromine ion. •It was proved that 0.08g of iodine can be adsorbed byl g of the impregnated carbon. •Removal efficiency and adsorption capacity of the impregnated carbon were far better than that of ionexchange resin or activated carbon. As a result, it is clarified that the impregnated carbon is an adsorbent applicable to the iodine removal from actual liquid waste.
Collection performance such as collection efficiency and surface collection efficiency is considerably important in order to select a suitable filter for the measurement of the concentrations of airborne radioactive particles. A simple method with imaging plates is proposed to evaluate the collection performance of air filters. By comparing the collection performance of some filters with natural airborne radioactivity as a test aerosol, it was confirmed that the method could reliably evaluate the collection performance of filters.