Cerenkov Counter for In-Situ Groundwater Monitoring of 90Sr

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