Radium-226 concentration in spring water sampled in high radon regions

Full text: Radium in natural water springs presents two main problems in radiological protection. The first problem is the direct 226Ra ingestion during the water consumption. The second problem is concerning the fact that the elevated radium concentration in water springs is the source of possible soil contamination by 226Ra and high radon concentration in the atmosphere of the dwellings situated over the contaminated place. Due to high radiotoxicity 226Ra is characterized by low action level (0.5 Bq/l for drinking water) and a high sensitivity technique is required to measure such low concentrations. The developed method of 226Ra concentration measurements is based on emanation technique: the specific activity of 226Ra is determined by radon volume activity measurement in closed system during the water sample bubbling. The main measuring steps are: Degassing, sealing and storage of the water sample during at least 2 weeks; Absorption of background 222Rn in the inner volume of measuring system consisting of radon monitor AlphaGUARD, set of glass vials AlphaKIT and air pump AlphaPUMP; Transfer of water sample in the system and beginning of air bubbling through the sample. Measurement of 222Rn concentration in closed system (at least 10 values of radon concentration) The minimum detected specific activity of 226Ra in such technique is 0.03 Bq/l without any need for preliminary radium concentration. After 2 week interval the water sample can be repeatedly measured. The 226Ra in water was measured in 4 regions with high levels of radon in dwellings: Ural (Russia), Niska Banja (Serbia), Caucasus (Russia) and Issyk-Kul (Kyrgyzstan). It was founded that high radon concentration in water (400-600 Bq/l) is not always lead to radium presence in the sample. In practically all of measured samples the radium specific activity was either below action level or a little above it. A close correlation between 226Ra in water and radon in dwellings was found only in Niska Banja and Caucasus. For these places the formation of travertine during the interaction of radium in water and limestone is typical. It should be noted that low 226Ra specific activity in water (approx. 0.15-0.4 Bq/l) can lead to high radium specific activity in travertine (up to 1000-1500 Bq/kg) and extremely high indoor radon concentration. The maximum 226Ra specific activity was measured in spring waters 'Slavyanovskaya' and 'Smirnovskaya' sampled in Zheleznovodsk (Caucasus) - 4.1 and 2.1 Bq/l. It should be noted that these waters are traditionally used as a mineral waters prescribed for treatment of gastrointestinal disorders during more then 150 years