Method development for quantifying strontium-90 in bovine bones

Abstract

In nuclear fission, fission products are produced, many of which are radioactive. The release of these radionuclides is viewed with concern by the public. In the course of the Fukushima Daiichi nuclear accident (2011), large activities of radionuclides were released into the environment. While other radionuclides (e.g., 134Cs, 137Cs, 131I, etc.) are not only volatile but also allow straightforward detection and quantification, 90Sr has been emitted in lower quantities and is notorious for its laborious sample preparation. Data on 90Sr from Fukushima are, therefore, scarce by comparison. With its chemical similarity to calcium and its relatively long half-life of 29 years, it poses a potential threat to human and environmental health. Due to its chemical properties, radiostrontium is known to accumulate in bone tissue. Previous studies have shown that, if any, increased environmental levels of 90Sr are to be found in close vicinity to the Fukushima Daiichi reactors. An interesting research opportunity arose when bones from a deceased cow that had lived approximately two kilometers from the reactor and was roaming freely for around one year after the accident were promised to the Applied Radiochemistry group at TU Wien.In preparation for the arrival of this precious sample material, an analytical protocol for the extraction of 90Sr had yet to be developed and is hence the topic of the present thesis. Since bone tissue is not generally regarded as a simple matrix, a complex sequence of sample preparation steps had to be developed. This included pyrolysis, acid digestion, solid phase strontium extraction, and analysis by liquid scintillation counting (LSC). The yield for this process was determined by spiking the sample with an internal, gamma-ray-emitting 85Sr standard.In this thesis, various bone samples were successfully prepared for strontium extraction. The extraction yield was demonstrated to be in the range of approximately 84 %. The present work provides a tool for the detection of radiostrontium in bone matrices, which may become valuable in the course of environmental monitoring following a nuclear release.