Impurities were analyzed in the benzene synthesized from an environmental sample for 14C measurement and influence of the impurities on 14C activity measurement was examined. Chloride, nitrite, nitrate, phosphate, sulfate ions were observed in the benzene. Contamination of inner glass surface of the synthesis line, especially traps, was found to be a source for these impurities. Toluene, ethyl benzene, o-xylene and grease which was used for connections and cocks in the line were detected. The amount of benzene-derivatives was small and did not act as quenchers in 14C measurement. On the other hand, a large amount of grease (DOW CORNING HIGH VACUUM SILICONE GREASE) was observed in the synthesized benzene, resulting in underestimation of 14C activity. Alternative grease (Shin-Etsu Co., Ltd.; FG-721) is insoluble to benzene. 14C concentration of NBS RM49 showed in good agreement with the recommended value when FG-721 was used, suggesting a suitability for the benzene synthesis.
The ionization chamber is one of the fundamental devices for radon measurement. Therefore, calibrations of the ionization chamber must be carefully carried out. We have performed calibrations of devices for measuring radon and radon progeny at our laboratory and on the site for several organizations since the 1960's. During calibration in the laboratory, air with radon emanated from a standard 226Ra solution with activity proved by the US National Bureau of Standards was used as the sample gas. We also participated in the OECD/NEA Radon Intercomparison and Intercalibration Programme arranged by Australian Radiation Laboratory (ARL) during 1984-1987. In 1984, we performed another radon Intercomparison experiment at Ningyotoge Works, Power Reactor and Nuclear Fuel Development Corporation (PNC) in collaboration with the PNC. In 1990, mutual-comparison experiments for radon concentration were carried out by four organizations (Nagoya University, Kyoto University, Waseda University and PNC) using the radon calibration system of Nagoya University. In 1995, the radon and radon progeny intercomparison experiment was performed between Japanese organizations and the US Environmental Measurement Laboratory (EML) using the radon chamber system at the EML. From these activities, it was clear that our radon calibration coefficient agreed well with those of other Japanese organizations with the exception of the Intercomparison experiment at Ningyotoge Works. However, our calibration coefficient was smaller than those of ARL and EML (92% of ARL/EML).
Radioactive materials to which an individual may be exposed are not rare. These potential sources of accidental radiation include medical and food sterilizers, therapeutic devices, industrial radiography sources, research laboratories, transportation accidents, nuclear medicine laboratories, and nuclear power plants. While radiation accidents occur infrequently, one of the problems is that ionizing radiation cannot be detected by the human senses. Contamination accidents involve not only some exposure to radiation as the individuals carry the radioactive materials either internally or externally, and are thus continually exposed to radiation until the contaminant is removed. The National Council on Radiation Protection and Measurements (NCRP) has published “Management of Persons Accidentally Contaminated with Radionuclides” as report No. 65. One of the chapters, entitled “Therapy Procedures and Drugs, ” details the decontamination of radionuclides. It is the goal of this article to outline and establish procedures and resources for the decontamination of contaminated individuals. Here, we review the treatment of contamination and describe drugs for internal decontamination in Japan.
If an accident occurs at a nuclear power plant and if it affects, or is anticipated to affect, the environment by radioactive material release, it is important to minimize consequences to the public by conducting appropriate protective measures, in evaluating source terms (an amount of fission products released to the environment), environmental radiological consequences, effects of the protective measures, and so on. It is also important to give necessary information on the protective maesures to the public so as to conduct the measures effectively. In order to support radiological emergency response measures and to contribute to improve emergency plans, the Japan Atomic Energy Research Institute (JAERI) is developing 1) a computerized support system for the Emergency Technical Advisory Body and 2) a computerized system for optimizing off-site emergency protective measures, and is studying appropriate information transmission methods in an emergency. This report describes current status of research on emergency response measures performed at JAERI.