In-situ detection of strontium 90 in groundwater boreholes with a novel detector at nuclear decommissioning sites

Strontium-90 is one of the primary beta-emitting radionuclides found at nuclear decommissioning sites. Monitoring its activity in the environment is of utmost importance given its radiotoxicity. Current procedures for the beta detection of strontium-90 are time consuming, produce secondary waste and expensive. Therefore there is a demand for more cost-effective detectors which can mitigate the downsides of existing techniques. This thesis discusses the design and development of a proof-of-concept detector which can meet the nuclear decommissioning industry’s demand for in-situ detection of 90Sr . Semiconductors were identified as an appropriate detector technology to use in a compact and water deployable detector. The current state of semiconductor detector technologies was evaluated and relevant semiconductor materials were compared using Monte Carlo simulations. Suitable detector components were researched and identified to fit a small scale form factor. Other practicalities were implemented such as rudimentary waterproofing. The basic operation of the detector and its sensitivity to radiation was demonstrated experimentally and its response to environmental conditions was assessed by changing the temperature of the water it was submerged in. The sensitivity of the detector to various radionuclides found in groundwater was evaluated using Monte Carlo simulations and the limit of detection for 90Sr was determined. The ability of such a detector to identify individual beta emitting radionuclides from a mixed spectrum obtained in a simulated groundwater borehole was demonstrated by using a linear regression technique