Advanced Radiation Sensing Techniques

Abstract

Real-time monitoring of alpha and beta emitting radionuclides in the environment and in mineral-processing has always proved elusive. The short path lengths, low target activities and harsh environments mean a quite specialised sensor is required. Two sensors have been constructed and tested with the sensitivity to measure gross alpha and beta particles below the activity level of 1 Bq/ml using optical fibres made of scintillating polymers. Scintillation allows for direct, real-time, semi-continuous measurements that are not available with current techniques. These polymers are suitable for withstanding the low pH solutions at elevated temperatures in abrasive mineral-processing environments. The new devices were found to be more sensitive by a factor related to the increase in their surface area and the new detection limit is now below 0.1 Bq/ml for the beta sensor and 0.15 for the alpha sensor. The feasibility of a novel sensing technique to specifically detect polonium- 210 (Po-210) is also investigated. The envisioned device would allow in-line sensing of Po-210 specifically by selective uptake onto a coated scintillator.