The air contamination of caused dy the operation of Kyoto University Reserch Reactor has been investigated. At the power of the reactor of 5000KW, the radioactive gas production observed are about 160μCi/sec activated by the opened beam tubes and also about 200μCi/sec by the primary coolant contamination, respectively. And the producions of radioactive dust is about 0.0003μCi/sec. It is clear that these amounts of concentrations may be changed by the conditions of reactor room ventilation, conditions of primary coolant and reactor power.
Theoretical and experimental studies on the multi-hole-collimator for α-ray detection are described. By using the collimator of lucite in 2mm thickness having a great number of holes of 0.5mm diamater directly in front of scintilation detector, it has been found possible to measure α-rays passing through the absorbent layer up to 95% of its range (about 40μ in tissue) with constant efficiency of 0.3%. In addition, by measuring α-ray spectrum, it is possisle to determine the distribution in depth of the source material. The resolution in this case is about 5% of the range of α-rays (about 2μ) in full width at half maximum. The measuring efficiency in using the multi-hole collimator, the resolution for the distribution of thickness in absorbent layer, and the maxmum thickness in which constant efficiency for measuring is obtained are analysed and solved theoretical as a function of variables determined by ratio of the diameter of the hole and thickness of collimator, and was identified in experiments good agreement in values. The less the ratio of the diameter of hole and the thickness of collimator, becomes, the longer maximum allowable absorbent layer for counting with constant efficiency become, and the better the resolution become, but the less in the efficiency of measuring are obtained.
In spite of the increasing use of electron microscopes, very few considerations have been given to the emission of radiation from the equipment. This is mainly due to the fact that the radiation is emmitted as “an unwanted by-product”of the equipment. Radiation surveys were carried out on twelve epuipments of Japanese manufacture. Informations obtained from the surveys were; 1) Radiation leakage was observed from eight equipments. 2) Electron gun, viewing window and photo-chamber were main locations where radiation leakage was observed. 3) Structural defects in the equipment were important causes of radiation leakage. Following opinions were offered from a health physics standpoint; 1) The equipment is required to be constructed and installed so as to provide adequate protection. 2) A legalistic radiation safety standard is neededfor theequipment manufacturer. 3) In a radiation safety program, it is important to obviate any radiation leakage rather than to assess the doses liable to be incurred.