Measurement of radium and radon in water using a combination technique of radon-emanation and pair-measurements methods

Highlights: • Combination method was used to measure ²²⁶Ra and ²²²Rn concentrations in hot spring water. • Alpha-spectroscopy based on radon-emanation and pair-measurement methods was used. • It expeditiously and accurately measures ²²⁶Ra and ²²²Rn in water within 8 d. Since ²²²Rn is continuously generated by the decay of ²²⁶Ra, it is difficult to analyze ²²²Rn in water containing ²²⁶Ra. To analyze ²²⁶Ra, a large amount of water is passed through a manganese fiber column to adsorb radium, and then radium delayed coincidence counting or gamma-ray spectroscopy is performed approximately four weeks later. A combination technique of radon-emanation and pair-measurement was tested to analyze ²²⁶Ra and ²²²Rn in water. ²²⁶Ra and ²²²Rn were accurately analyzed within approximately 8 d.