[Concentration measurement of 85Kr dissolved in the solution with GM counter (author's transl)].

When 85Kr gas is used as an internal radiation source for chemical reactions in liquid phase, it is necessary to check after irradiation whether the radioactive concentration of 85Kr dissolved in the solution is below permissible level or not. Measurements were made on solutions ranging in concentration from 1 X 10(-3) approximately 1 X 10(0)kBq/g (1 X10(-4) to 1 X 10(-1) microCi/g) by the use of an end-window GM counter for beta-rays. In the present paper, the method of making up the calibration curve for 85Kr solution is studied, together with some problems in measurement. The calibration curve for 85Kr solution was represented as N = 1.8 X 10(5) C. In addition, the method for measuring concentration of dissolved 85Kr was established by resolving problems relating to the volatilization of 85Kr in measurement.