A radioactive cloud released into the atmosphere from the stack of a nuclear facility may cause direct or indirect exposure on the public around the site through some pathways. In this report are outlined the so-called general Gaussian formula with F. Pasquill's data for radioactive concentration distribution in the cloud, submersion model for β and γ exposure to the cloud and direct calculations of cloud γ exposure, radioactive deposition on the ground, and others. The estimation by A. Adams of whole body γ dose which was used in H. J. Dunster's assessment of 85Kr dose is questioned. A calculation method of annual population dose arround a site under normal operation condition is mentioned. Meteorological condition assumed in safety analyses for emergency are discussed by taking examples of U. S. AEC Safety Guide 3 and 4 as well as the guide in Japan.
The whole body monitor of JAPC Tsuruga Atomic Power Station got started operation on Sep-7th, 1970. The number of measurements of workers reached 5101 on Dec. 31st, 1971. From these experiences, it became evident that whole body counting in routine monitoring is useful for both the improvement of working environment and the diminution of the cause of body contamination. The change in frequency distribution of the counting values of all the subjects suggests a change in the state of contamination control. This paper, moreover, referred to the screening level and procedure for whole body monitoring.
From the experiences in individual monitoring at Tsuruga Nuclear Power Station of JAPC, it has been shown that measured values of the film badge worn by radiation workers exceed those of the pocket dosimeter placed in the same position of their bodies. In order to solve this problem concerning the individual monitoring, γ-ray dose rate spectra were measured in the working places of the nuclear power station and the response of the film badges was compared with that of other monitors. The following results were obtained; 1) The contribution of γ-ray of the energies higher than 3-MeV to total γ-ray dose rate is greater than a half at the working places examined. 2) Measured values of the film badge with Cd and Pb filters are relatively larger than those of other monitors. From the discussion about individual monitoring, it is concluded that it is important to improve the accuracy of individual monitor to be used at high energy γ-ray field.
In the nuclear power and radioisotope handling facilities, one of the most important problems is a radioactive contamination on skin. Hand skin contamination occurs very often in the operation area and such surface contamination must be removed as soon as possible to protect an internal contamination. From 1967 to 1971, training courses for skin decontamination had been held with total 350 of trainee based on JAERI radiation protection manual at the Oarai Research Establishment. In the training courses, fresh pig skin samples used instead of human skin were contaminated with 137Cs, 131I, 144Ce and 239Pu aqueous solution, respectively. These samples were washed practically by trainee with the skin decontamination method recommended in the manual. Results obtained in the courses showed that such training itself is a significant work and this skin decontamination method is an excellent first aid.
Half-face masks have been used routinely at plutonium facilities in the Power Reactor and Nuclear Fuel Development Corporation. In 1970, a mask man-test began to evaluate the protection efficiencies of masks when wearing and to instruct workers how to wear them properly. DOP was used as a test aerosol, and 232 persons were tested. In the first test 70% of the persons could wear the masks with a good fit (leak rate less than 1%). The persons with leak rate over 1% were repeatedly tested to investigate causes of the leak. The persons were classified into three groups; the first one having experience of wearing masks, the second one having no experience and the third one being given some instructions about masks before the test. The persons in the first group weared the masks better than those in the second group, but the test suggest the instruction is the most effective. The methods procedures and results of the tests are described.