MEASURING DEVICE FOR UNDERWATER RADON CONCENTRATION AND RADON CONCENTRATION MEASUREMENT USING SAME

摘要

PURPOSE: To easily measure radon which has an extremely low concentration and is dissolved in water by dipping a measuring device with carbon deposition film into water to be measured and then detecting the track of α particle generated by radon. ;CONSTITUTION: Carbon electrodes 2, 2 are provided inside a vacuum chamber 1, a plastic film 3 which is for example 20×20×1mm is laid out below it, and spark discharge is made for 90 seconds under a degree of vacuum of 5×10^-4Pa and a spark current of 35A, thus forming a carbon deposition film 4 which is 10-15μm thick on the film 3. The carbon deposition film 5 is not peeled, is stable against an organic solvent, and does not react with radon in air. For measuring the radon in water, the film 5 is set to a holder 6 made of teflon and is suspended by a drilling hole, etc., by a wire 7. After the film 5 is dipped into the water to be measured for a certain amount of time, it is etched by 6 N NaOH, the number of α particles is counted by a microscope, and then radon concentration within water is measured, thus estimating the state of underground water and crack of rock ground.;COPYRIGHT: (C)1994,JPO&Japio