Kousuke Katsurayama

Feasibility study on a continuous environmental gamma-ray monitor using a NaI(Tl) scintillation spectrometer.

Energy spectra of gamma rays due to artificial radionuclides could be estimated by using a NaI(Tl) scintillation spectrometer on the basis of the analysis of natural environmental gamma rays. This analysis system was applied to a continuous gamma-ray monitor in the vicinity of a nuclear facility, and a plume exposure rate due to gaseous effluents of about 6 X 10(-2) Ci hr-1 (2.2 X 10(9) Bq hr-1) could be estimated successfully downwind from the stack.

A method for measuring each concentration of β-emitting nuclides mixed in air

Abstract The authors developed a new type of instrument for continuous measurement of each concentration of β-emitters mixed in air. The instrument consists of a series of several unit double cylindri chambers. Air containing cylinder. The space between the outer and the inner cylinder walls serves as the ionizing section. The thickness of the inner cylinder wall for each unit chamber is different from one to another. The concentration of each β-emitter was calculated from the measured ionization current using calibration constants, which were evaluated using both the Monte Carlo calculation and experiment. The following three combinations of nuclides were taken for the study of performance of this type of instrument: 85 Kr with 41 A, 15 O with 13 N, and 3 H with 85 Kr.