Tradescantia in studies on genetic effects of low level radiation is briefly introduced. Radiosensitivity, method of screening stamen hair mutation, materials in current uses, spontaneous mutation rate, and modifying factors are refered. For stamen hair mutation b values in exponential model were lower in irradiation with low dose rate and at high environmental temperature. The dose response curves under these modifying conditions, when extrapolated to low dose range, well fit to the line which was obtained by Sparrow's experiment of low level irradiation. In chronic irradiation, the frequency of stamen hair mutation reaches to the constant value after 17 days from the start of irradiation, and is as much as 4 times higher than the peak value in one day irradiation at the same exposure rate. The spontaneous mutation rate of KU-7 varied with temperature. The increase with 1°C increment of mean temperature was -0.04%. Uses of Tradescantia in monitoring the environmental radiation is discussed.
The movements of 10 radionuclides in the water-saturated soil were studied. Clay loam or sand obtained from reactor sites, and Toyoura standard quartz sand were used as a soil sample. Breakthrough curves and sorption distributions of radionuclides along soil columns were observed under various conditions such as pH, coexisted ions and the kinds of teaching solution. The results obtained are as follows: (1) the divalent ions such as 54Mn, 85Sr, 60Co and 65Zn were not adsorbed so intensively, and high mobilities were observed, (2) the radionuclides of 137Cs and 144Ce were extremely adsorbed on soil surface, and their mobilities were not so high as to the divalent ions described above, (3) the radionuclides of 106Ru, 95Zr, 95Nb and 110mAg were retained largely in the soils, but some parts of their radionuclide moved as easy as to the divalent ions in soil water system.
Many series nuclides contained in environmental substances were conducted by both physical decay process and some dynamical processes that consist of physical, chemical and biological processes. Physical decay process is remained after the stop of the dynamical processes by a sampling procedure and so on. Radiochemical determination of series nuclides, such as 210Bi and 210Po in a sample is done at the very state. The authors calculated and described the decay charts of 210Pb-210Bi-210Po series at several given initial radioactivity ratios of these nuclides in this report.
Diffusion coefficients of radionuclides in some porous structural materials and porous components of earth stratum are important as the basis for the safety evaluation of the storage and disposal of radioactive wastes. In our previous works, the method of analysis and experiment using a permeative type diffusion cell for measurement of effective diffusion coefficient was established, and experimental results were reported. In this paper, effective diffusion coefficients of 3H2O in mortar, concrete, brick, clay layer, and sand layer were measured, and characteristics of these pore structure were discussed on the basis of tourtusity factor.
In the Tokai Research Establishment, most of the radioactive liquid waste is transferred to a wastes treatment facility through pipe lines. As part of the pipe lines a cast iron pipe for town gas is used. Leak test has been performed on all joints of the lines. For the joints buried underground, the test was made by radioactivity measurement of the soil; and for the joints in drainage ditch by the pressure and bubble methods. There were no leakage at all, indicating integrity of all the joints. On the other hand, it is also known by the other test that the corrosion of inner surface of the piping glue to liquid waste is only slight. The pipe lines for transferring radioactive liquid waste are thus still usable.