屋外ラドンおよびラドン娘核種濃度の連続測定

抄録

The concentrations of outdoor radon and its progeny were measured every three hours. An electrostatic collection method for radon and three count techniques for radon progeny were adopted to measure the concentrations continuously. The measurements carried out from Feburary 1991 to June 1992. The equilibrium equivalent thoron concentrations were also measured with a radon progeny monitor. The concentrations of radon and its progeny showed the same diurnal variation of a maximum in the morning and minimum in the evening. An averaged equilibrium factor (F) was 0.76 over the whole period. The ratio of radioactivity concentration, ²²²Rn: ²¹⁸Po: ²¹⁴Pb: ²¹⁴Bi, was 1.00: 0.80: 0.78: 0.72 in outdoor air. In comparison with outdoor radon progeny, the outdoor concentration of thoron progeny was about 1/40 and human exposure was about one-tenth.