2007 年 42 巻 3 号 p. 247-254
The study on the establishment and maintenance of the traceability on radon measurements at the Ningyo-toge Environmental Engineering Center of the Japan Atomic Energy Agency (JAEA Ningyo-toge) is illustrated in this paper. The primary standard is a radium solution provided by the National Bureau of Standard (present the National Institute of Standards and Technology) in the USA, and the secondary standard is the method with gas-filled ionization chambers calibrated with the solution. The radon reference chamber is utilized to provide reference atmospheres in calibration experiments for other monitors. Through the intercomparison experiments among the international reference institutes, it was confirmed that the reliability and consistency of the secondary standard of the JAEA Ningyo-toge have been retained since 1984. It shows that the calibration and measurement techniques associated with the traceability system constructed have been maintained well at the JAEA Ningyo-toge. Since there is no reference field as a national standard and no method regulated by the Japanese Industrial Standard, this paper provides not only reliability and accuracy of the radon measurements at the JAEA Ningyo-toge, but also useful information for the standardization of radon measurements in Japan.