A position sensitive proportional counter based on the tilted wire position reading method was examined with a view to the position dependency of detection efficiency for thermal neutrons, and was applied to the measurement of the thermal neutron space distribution at a neutron-guide channel, with a collimator of 5 cm diameter, of Kinki University Reactor (UTR-KINKI) . The counter consisted of a pair of position-sensing wires extended in parallel each other but tilted against the anode wire. The effective detection length of the counter was about 6 cm, and sintered boron nitride was employed as neutron converter in order to obtain uniform thickness of boron layer. The result showed that the constant detection efficiency was realized in about 4 cm center region of the counter. The thermal neutron space distribution was found to have a flat top part of about 2 cm diameter.
Agaricus (Agaricus blazei Murill) is one of a popular crude drug in Japan and East Asia countries. The crude drugs originating from natural raw products are easy to be contaminated by microorganism. Radiation method has been introduced as the sterilization technology for crude drugs. ESR has been used for the detection of radicals in irradiated drugs. Using ESR, we detected radical species in Agaricus before and after the gamma ray pasteurization. The ESR spectrum consists of a broad sextet centered at g=2.0, a singlet at same g-value and a singlet at g=4.0. We found that relaxation times of radicals in Agaricus varied by the presence of oxygen. Upon substitution of air by Ar, i.e., the absent of oxygen in the ESR sample tube, the T1value became 10 times larger than the presence of oxygen. Accordingly, the progressive saturation curve indicates more immediate saturation under the Ar than air atmosphere. Radicals, produced by the γ-ray irradiation to Agaricus, are very sensitive to oxygen. We concluded that ESR spectrum of irradiated Agaricus sample in the absence of oxygen is useful for the detection of dose level of γ-ray irradiation.
Six shoe-deodorants on the market were analyzed using gamma-ray spectroscopy and radionuclide imaging techniques. The results reveal that at least three deodorants were“radioactive consumer products” containing radionuclides of thorium (Th) series, uranium series, and potassium-40 that were added intentionally. Equivalent dose rates and effective dose rates were calculated using the activities in these deodorants. There were no samples breaking the nuclear reactor and fuel regulation law. Radioactive concentration of the deodorant for a shoe-shelf is higher than other deodorants, and the total concentrations of daughter nuclides of Th which are radioactive equilibrium with224Ra exceeded 90 Bq·g-1. The effective dose rate at one meter from the shoe-shelf-deodorant is 8.6×10-4, μSv·h-1. Another type of shoe-deodorants is an insole that causes the surface dose of plantar skin. The equivalent dose was calculated as 1.9 μSv·h-1at one millimeter from the insole. This study suggested that it needs to watch severely over the deodorants because many kinds of deodorants are used in home and some deodorants are radioactive consumer products.
A newly designed electrolytic device to enrich tritium in environmental water is proposed. This device is composed of a solid polymer electrolytic film (SPE film) and porous, dimensionally stable electrodes (DSE) . In our design a platinum mesh was inserted between the SPE film and the anode DSE so that the device can be easily disassembled and the used SPE film can be replaced with a new one after each use. A thin gold plate with a number of minute holes in it is used as current collector in both electrodes allowing the electrolytic gas to be released progressively. An electrolytic current of 6A was passed through the device to obtain a volume reduction factor of five by keeping a temperature of water bath at 2°C or lower. After that, our device achieved a tritium recovery factor of 0.836 ± 0.021 (n=4) . Such a value is greater than the value obtained using a commercially available apparatus operated under the same experimental conditions. It is thought that this greater efficiency depends on the difference between electrolytic temperature produced in our device and the temperature in the commercially available one.