Uranium, thorium and potassium contents and radioactive equilibrium states of the uranium and thorium series nuclides have been studied for 2 phosphate rocks and 7 phosphate fertilizers. Uranium contents were found to be rather high (39-117 ppm) except for phosphate rock from Kola. The uranium series nuclides were found to be in various equilibration states, which can be grouped into following three categories. (1) Almost in the equilibrium state, (2) 238U≈230Th>210Pb>226Ra and (3) 238U>230Th>210Pb>226Ra. Thorium contents were found to be, in general, low and appreciable disequilibrium of the thorium series nuclides was not observed except one sample. Potassium contents were also very low (less than 0.3% K2O) except for complex fertilizers. Based on the present data, discussions were made for the radiation exposure due to phosphate fertilizers.
The excitation functions were measured for the nuclear reactions of55Mn (p, 4n) 52Fe and55Mn (p, n) 55Fe by using thin manganese disks, specially prepared under a pressure of 200-250 kg/cm2at 400-500°C for 0.5-1 hour. The maximum cross section in the excitation function for the55Mn (p, 4n) 52Fe reaction was found to be 1.4 mb at Ep=54 MeV. From the yield curve, 24.8 MBq/μA h (670μCi/μAh) of52Fe was estimated to be produced with 0.45%55Fe contamination in the energy region between 73 and 39MeV. Iron-52 was produced in the yield of 85-93% to the expected value from the yield curve in the energy region of 44-60 MeV. For the separation of52Fe, the radiochemical yield of52FeCl3was 70-92% and its radionuclidic purity was higher than 99%. Manganese-52m was obtained repeatedly by eluting the anion exchange column adsorbing52Fe with 6N-HCl in 99.9% radionuclidic purity and 86% yield to the expected value. The amount of55Fe in a large quantity of52Fe could be determined in 1-2 days from end of bambardment (EOB) by analyzing decay curve of Mn-Kα-X ray from52Fe and55Fe.
The experiments on the degassing of dissolved85Kr by the N2-stripping method were carried out to examine the influence of temperature and properties of solvent, as well as flow rate of N2gas on the degassing efficiency. The half-life period in case of the decrease in concentration of the dissolved85Kr which was used as an index of degassing efficiency, was proportional to the reciprocal of temperature and was inversely proportional to the flow rate of N2gas. It became longer with increasing the viscosity of solvent. No influence on the degassing efficiency was observed to be exercised by the solubility of Kr gas in solvent and the surface tension of solvent. For organic solvents belonging to a homologous series, the half-life period became longer with increasing the carbon number, molecular weight and boiling point of solvent, respectively.
Thallium-201 distribution in the blood was investigated both in vivo and in vitro. Thal-lium-201 was distributed into the erythrocytes and plasma with the ratio of 1.4±0.3 to 1.0, immediately after its administration. The uptake of201Tl into the erythrocytes in vitro were affected by the incubation temperature and the presence of ouabain and KCl; indicating that the201Tl was uptaken into cells partly through their membranes Na, K-ATPase. Erythrocytes could retain201Tl in it, whereas201Tl was present as free ion in the plasma. Thallium-201 was flew out of erythrocytes into the plasma, keeping the ratio of201Tl in erythrocytes/plasma to be 1.9±0.2/1.0.
Measurements of fallout207Bi in environmental samples were reported for water filters used at the Scott Base in Antarctica and the surface soils containing high amount of fallout nuclides. The level of207Bi in these samples was found to be nearly the same or a little higher than that of fallout60Co and the207Bi/137Cs activity ratios were in the range of 0.001-0.018. Contamination of bismuth by207Bi was found in “high purity” bismuth on market and its level was measured to be 1.9 mBq/g-Bi.
Utilization of the computer for radiation control is planned and performed in many radioisotope laboratories. But each laboratory has their own situation which makes the planning difficult with respect to the hardware and particularly to the software. What is the most important is that the practice of radiation management is different for each laboratory both in point of view and in the form of recording. Therefore, the computer program for the radiation management, especially for the management of radioisotopes is required to meet many amendments. In this standpoint, we have developed a “programless language” or “programless software” and have used in our work for several years. As the result of our experience, we have found that the programless language is quite satisfactory for the management of radioisotopes and that it has an advantage in some aspects over conventional programs. It is thought that this “programless language” is effective not only for our own works, but also applicable to other radioisotope laboratories.