Concentrations of thorium and uranium are measured in the front glass of CRT (cathode ray tube) of television sets by the two methods of the γ-ray spectrometry and the neutron activation analysis. In the former method, measurements are made on an assumption of the radioactive equilibrium in the respective series of thorium and uranium. The concentrations obtained by the two different methods agree well within experimental uncertainties, showing the radioactive equilibrium in the present samples. It is found that the thorium and uranium concentrations in the glass can be measured by the γ-ray spectrometry as well as by the neutron activation analysis. Moreover, the concentrations of thorium are generally higher than those for uranium. This trend is consistent with that of the natural abundance for thorium and uranium in the earth's crust.
Tritium (3H) concentration and stable isotopic ratios δD and δ18O are important environmental tracer data. In Hokkaido, however, hydrological studies using these data were difficult due to a lack of environmental tritium and the altitude isotope effect values. In this study, 3H concentrations of Hokkaido wine were measured to estimate the past rain3H concentrations. In addition, environmental δD and δ18O samples taken on Mt. Daisetsuzan, the highest peak in Hokkaido, and in the Tokachi Plain were measured. The results obtained are as follows: Estimated concentrations of3H in Hokkaido were higher than those in Tokyo and Tsukuba, and were consistent with geographical3H levels in rain around Hokkaido. Some model calculations suggested that the3H concentrations in the 1950's and 1960's were at least 30% higher than those in Tokyo. The altitude isotope effects obtained were -1.75±0.30‰/100m and -0.24±0.01‰0/100m for δD and δ18O, respectively. These values are almost the same as, or slightly lower than those in the Chubu and Tohoku districts. Using these data, the approximate age of groundwater and the altitude of original precipitation could be estimated.
Accumulation of137Cs in trefoil (leaf and stem), “Mitsuba”, Cryptotaenia japonica Hassk, with or without root was investigated to prepare higher radioactive plant in hydroponic culture medium (140-150 Bq/ml) . It was found that137Cs concentration in plant tissue was increased with time, as high as 1.6 times of that in the culture medium after 4 days. On the other hand, 137Cs concentration was affected by carrier element (Cs > 6ppm) and coexistent elements in the medium. Radioactivity of the plant after 4 days was shown to be sufficient for successive experiments.
The comparative study of the blood clearance tests of99mTc-Phytate (99mTc-P) and indocyanine green (ICG) was undertaken in liver-injured dogs with D-galactosamine (GaIN) . The blood clearances of99mTc-P and ICG in dogs decreased with the increase in dose of GalN and with the time elapsed after GalN administration. As compared with the blood clearance test of ICG, the blood clearance test of99mTc-P in dogs was found to be more sensitive in detection of the hepatic dysfunction with mildly damaged stage, but to be relatively inaccurate in detection of the hepatic dysfunction with severely damaged stage induced by GaIN.
A NaI-NaI coincidence low background counting system has been constructed to be used in radioenvironmental measurements. The slow timing technique, using the constant fraction timing single channel analyzer and coincidence unit, was used in the present system. The coincidence efficiencies of systems employing two and four NaI (Tl) detectors have been evaluated. A scintillation preamplifier with multiple inputs was constructed for summing the outputs of PM tubes. The performance of the system was tested using radioactive point sources and environmental samples. The detection efficiency of the NaI-NaI coincidence system employing four NaI (Tl) detectors was found to be high enough to measure low-level γ-ray activity of desired isotope in environmental samples with neither high background contribution nor interferences from other isotopes.