Determination Of Gross α/β Activity In Drinking Water Based On HPGe Water Online Gamma Measuring System

Water is an indispensable natural resource for human survival and development.The potential health effects of radioactive nuclides dissolved in drinking water have drawn attention worldwide.Many countries and regions have adopted the guidance standards issued by the world health organization（WHO）in 2004,in which the radioactive activity of drinking water for residents has been clearly regulated.Based on the upper limit of annual average radiation dose of 0.1mSv and the standard of 2L drinking water per adult per day,the total radio activity in drinking water of residents should not be higher than 0.5Bq/L and 1Bq/L for grossαandβrespectively.The XGT-2000 HPGe detector water radiation monitoring system is used to indirectly calculate the grossα/βactivity of water by detecting the gamma ray energy spectrum of water.This new method allows real-time monitoring of the grossα/βactivity of the water by sampling directly from the water source in the field environment,without the need for complex processes such as evaporation of water samples,thus requiring less of the operators and no pollution to the environment in the process.Analysing the contribution of radio nuclides from water source and then select some specific radio nuclides for grossα/βcalculation purpose.Choosing ²²⁶Ra,²²⁴Ra withγray energy of 0.186MeV,0.241MeV for grossαcalculation and ²¹⁴Pb,²⁰⁸Tl,²¹⁴Bi,⁴⁰K withγray energy of 0.352MeV,0.583MeV,0.609MeV and 1.46MeV for grossβcalculation.Establising a mathmatical equation betweenγenergy and grossα/βradio activity.Conducting surveys from August 2017 to December 2017and from March 2018 to September 2018,regardingγspectrum of the water source,in Dongfeng channel and Pixian Min river respectively with the use of XTG-2000W water radio activity monitoring system.Calculation results come after the procedures of smoothing,peak-seeking,background-deducting onγspectrum.Mean grossαradioacitiy are 0.0379Bq/L and 0.0234Bq/L for Pixian Min river and Dongfeng channel respectively while mean grossβradioactivity are 0.0749Bq/L and0.0432Bq/L for Pixian Min river and Dongfeng channel respectively.To virify the accuracy of this method,the 3 litter water sample are taken from each place to do a lab test in Sichuan Radioactivity Management Monitoring Center for the result of grossα/βradioactity.Comparison of both results show the deviation of grossα/βfor Pixian Min river are 51.4%and 21.8%respectively and for Dongfeng channel are41.5%and 4.34%respectively,and both result differences are in the same order of magnitude.