Cerenkov Counter for In-Situ Groundwater Monitoring of ⁹⁰Sr

Abstract: Groundwater contamination from ⁹⁰Sr is an environmental challenge posed topresent and former nuclear weapons related sites. Traditional methods of extractinggroundwater samples and performing laboratory analyses are expensive, time-consumingand induce significant disposal challenges. The authors present here a prototype countercapable of measuring ⁹⁰Sr groundwater concentrations in-situ at or below the drinking waterlimit of 8 pCi/liter. The ⁹⁰Y daughter of ⁹⁰Sr produces high-energy electrons, which cancreate Cerenkov light. Photomultiplier tubes convert the Cerenkov light into an electronicpulse, which then undergoes signal processing with standard electronics. Strontium-90concentrations near the drinking water limit can be measured in a matter of hours if it is insecular equilibrium with the ⁹⁰Y daughter. The prototype counter is compact, can bedeployed in an American Standard 6-inch, well while operated by a single person, andtransmits the results to a central monitoring location.