The experience of radiation monitoring in the Electrical Communication Laboratory was reported. Personnel monitoring, laboratory monitoring and field monitoring are main activities in the laboratory and have been carried out from 1962 to the present time. The methods of monitoring and the working limits are almost followed to those used in the Japan Atomic Energy Research Institute. The personnel exposure to radiation, the frequency distribution of white blood cells, the radiation levels the contamination of floor surfaces in the laboratory and the concentration of radioactive waste water were measured and several practical data were obtained. These data showed that no significant exposure is present for the personnel. Furthermore, it was shown that the radiation levels are kept lower than the maximum permissible levels.
At present, 4 grams of plutonium have been used at the plutonium laboratory in JAERI, and in the near future 100 grams of plutonium will be coming in use. As well known, plutonium is high radiotoxic material and then more severe radiation control is demanded. In this paper, radiation control methods at the plutonium ladboratory such as contamination control, room air monitoring, stack dust monitoring and solid and liquid wastes control are discribed.
In our country, the treatment and disposal of radioactive wastes from fuel reprocessing plant will be of great importance within a few years. From this prospect, studies on the possiblility of disposing these wastes into the deep sea are urgently needed. In this study, neutralized liquid waste having the same chemical composition as one from Purex-reprocessing was solidified with cement, then the compression strength of the specimen and the factors affecting to its strength were examined. Results are as follows. 1) Generally, compression strength was reduced exponentially with the increase of waste-cement ratio weight or with the dilution of the waste with tap water. 2) The largest strength, 680kg/cm2, was obtained in the case of solidifying the waste neutralized with Ca(OH)2 under conditions of no dilution of the neutralized waste, waste-cement ratio of 120% and curing time of 28 days. In the case of neutralization with NaOH, the largest strength was 420kg/cm2. 3) Volume increase ratio between the solidified cement specimen and the waste water before solidification was 1.5 in the case with Ca(OH)2, 1.7 with NaOH under the same conditions as above. 4) Important factors affecting to strength were dilution of the waste and waste-cement ratio when Ca(OH)2 was used as neutralizer, and waste-cement ratio and curing time in the case with NaOH.
Contamination limits on the skin surface employed as a guide of the radiation protection for occupationally exposed individuals are derived by taking into account the external exposure dose to the skin and the internal exposure dose recieved by the inhalation, ingestion and skin penetration of the contaminants. The adequacy of the derived limits is discussed in relation to the detection probability of a hand-foot monitor for the hand contamination. The contamination limits for the skin, which have been adopted in other establishments, are also reviewed together with the general basis of the derivation.