Tissue distribution of intravenously injected polymeric plutonium in mice was studied by liquid scintillation counting. The purpose of this study was to know the effect of plutonium administered at different dose levels on its distribution to the tissues. The fraction of deposition and average dose rate to the highly radiosensitive tissues such as the bone marrow and testes were also of our concern. The polymeric plutonium prepared in this institute was demonstrated to have colloidal properties by showing high deposition in the liver and spleen for a long time. Percent uptakes of plutonium in the main tissues except in the kidneys were not influenced by the three different doses from 5μCi/kg to 15μCi/kg body weight of 239Pu. At 28 days after injection, femoral bone, femoral marrow and testes contained 1.23, 0.18 and 0.063 percent of the injected doses, respectively. At 56 days, the uptakes of the plutonium in the same three tissues were 1.23, 0.17 and 0.057 percent respectively. Average dose rates to the liver, lungs, kidneys, testes and femoral bone were proportional to the amount of plutonium administered. On the other hand, average dose rates to the spleen and bone marrow were characteristic in that they were not proportional to the amount of plutonium administered. Elevated dose rates (rad/day) were obtained in the spleen and the bone marrow, where there were weight losses resulting from the internal exposure to the deposited plutonium. Therefore, radiation dose to the spleen and bone marrow can not be solely obtained in proportion to the administered dose.
Exchange reaction of tritiated hydrogen to water vapor under the condition of tritium gas concentration between 1μCi/l and 1mCi/l was studied. Tritium gas with hydrogen gas of 5 Torr and water of 20mg were enclosed in a Pyrex glass ampule with volume of about 100ml. The mixed gas with water vapor was heated with electric furnace. The heating time was between 2 and 100hr, and the temperature was 776, 725, 675, 621, and 570.5°K. After heating, tritiated water was trapped with liquid nitrogen, and counted with a liquid scintillation counter. The radioactive concentration of initial tritiated hydrogen was measured with a calibrated ionization chamber. The main results obtained are as follows; 1) the concentration of produced tritiated water is well proportioned to that of initial tritiated hydrogen, 2) the activation energy of exchange reaction from tritiated hydrogen to tritiated water is 26.2kcal/mol and that of inverse reaction is 27.4kcal/mol, 3) the reaction rate at room temperature which calculated with activation energy is 1.04×10-13day-1, and then exchange reaction at room temperature is negligible.
Radioactivity concentration of scrub water in wet type incinerator increases gradually by the accumulation of radioactivity owing to its circulating operation. Some part of the radioactivity is released again into the off gas by the vaporization of water. In the study, two theoretical expressions concerning the radioactivity concentration in the scrub water and the amounts of radioactivity in off gas were proposed. In this incineration tests, 3H is selected as a representative nuclide, while other nuclides are discussed later. These expressions can show clearly the factors which affects the radioactivity in the off gas. The calculated data based on the expression are compared with the observed one on the radioactivity concentration in the scrub water. The result of the comparison shows that the theoretical expressions can give a pretty good estimation.
Tritiated water is one of the radioactive wastes which are produced at atomic facilities. Tritiated water behaves as well as ordinary water and ‘therefore’ it is difficult to remove tritium from radioactive waste water alike other radioactive nuclides. We thought that it is an effective method to fix tritiated water using the hydration of cement. Generally, 3CaO·2SiO2·3H2O and Ca(OH)2 are mainly produced at the hydration of cement in which 25 weight percent water of cement is consumed. Therefore, making use of this action, it is expected that tritiated water would be fixed as the structure of these compositions in the hydrated cement. Although it is already found with simple experiments that most tritiated water transfers to surrounding water, yet it is incorporated using the hydration of portland cement. We tried, accordingly, to investigate the mechanism of the transfer phenomenon of the tritiated water fixed with cement. In this report, we showed the results and some considerations of basic experiments, concerning the effects of kind of cements, curing period, soaking period in water, presence of gel. water, and concentrations of salts and alkalis in surrounding water.
Concentrations of 222Rn, 220Rn and their daughter products in the atmospheric air have been measured at various locations and altitudes. The results are as follows: (1) Daily geometric mean value of 222Rn daughters on the campus was 91.0pCi·m-3 and the concentrations observed in the daytime, nighttime and all day showed logarithmic normal distributions. (2) The maximum concentration of 222Rn appeared between 600 and 800 hours, and the minimum in the afternoon through the year. (3) A seasonal variation of 222Rn daughters with winter maximum and summer minimum was obtained on the campus. (4) Annual variation for 13 years was not found clearly. (5) The concentrations of 222Rn in the outdoor air differ from place to place, and it amounted from 10 to 1370pCi m-3 at different environments. (6) The concentration of 220Rn decreased rapidly with altitude and the inverse correlation was observed between concentration of 220Rn and the wind speed near the ground.