A possibility for measuring a-rays from241Am radiation source, natural zircon sands and fractures in a house floor made from concrete were investigated by using the Imaging Plate (IP) . Energy dependency of PSL value for a-particles was determined, having 0.5 PSL unit per a-particle at 5.490 MeV of radon a-ray. Concentration of radon, suggesting radon gas escape from zircon sands, could be obtained by IP, and its PSL values of spots were around 0.5. Using these basic properties for detecting a-particle on IP, radon escape through a fracture in a concrete floor inside building could be measured by IP. The fracture shape was recognized as a radiation image of IP, and PSL values of spots were classified into three groups of 0.5, 0.7 and 1.0. These facts suggest that radon escape including its daughter nuclides has been captured on the IP. Measurement of radon escape through fractures using IP could be applied to new nondestructive testing technique of fractures in concrete materials of a building.
Nodulating (T202) and non-nodulating (T201) soybean isolines were hydroponically cultivated, then nitrate labeled with13N or15N, was added to the culture solution in order to investigate the nitrate absorption and transport in soybean. The accumulation pattern of the absorbed13N in the first trifoliate was observed by positron emitting tracer imaging system (PETIS) as well as bioimaging analyzer system (BAS) . The15N abundance of each part was determined by emission sjectrometrv. Real time changes in two dimensional image of the radioactivity could be monitored by PETIS, besides the distribution13N in whole plant could be observed by BAS. However quantitative data were hardly obtained by the13N analysis. Stable isotope15N is more reliable in the quantitative analysis in each part. Combing the data obtained by15N and13N tracer experiments, the absorption and translocation of N in plant should be more clearly figured out.
Elimination of137Cs from highly accumulated trefoil (leaf and stem) through boiling in distilled and salted water were investigated in relation to study the effect of cooking and processing on biochemical states of radionuclides (RI) contaminat-ing in foods. (1) 137Cs was hardly eliminated from the trefoil immersed in a distilled water at room temperature (about 15°C) during 10 min. (2) 137Cs was considerably eliminated from the trefoil when boiled in a distilled water, 0.3-3.0% salt concentration of the water and soy sauce: about 40-60% (after 2 min), 70-85% (5 min) and 80-90% (10 min), respectively. (3) Elimination of137Cs in the soy sauce (e.g. 77.0±2.9%, at 1% salt concentration after 10 min) was restrictive comparing to that in the salt water (93.4±2.3%) . These results are expected to contribute to evaluate the radiation exposure to man when a boiled trefoil contaminating with 137Cs was ingested.
An radioactivity monitor for waste solution has been constructed using a liquid scintillation technique, which enables beta-emitter mixture to be analytically radioassayed. The method of least squ-ares has been applied to the radioassay for relatively low-level beta-emitter mixture in radioactive waste solution. This system can get rid of the difficulty of analysis for beta-emitter mixture in a mon-itoring sample, and provides fundamental information for subsequent waste-treatment. Detection limit of five nuclides was estimated to be about 0.02 Bq/cm3, which is sufficiently low compared with the values of authorized safety guideline.