Moesgaard Simon (tankerair00)
The ability of the autoradiographic device BeaQuant™ is evaluated herein to quantitatively map the ultratrace element 226Ra distributed spatially in celestine (SrSO4) grains/crystals. 226Ra doped celestines have been obtained from coprecipitation and recrystallization experiments, and have been characterized with high purity germanium gamma detector (HPGe), giving specific activities ranging from 3251 to 32523 Bq.g-1. Alpha autoradiographs of polished sections from doped celestines have been obtained using BeaQuant™. These alpha maps have been compared to the celestine grains/crystals arrangement observed with a scanning electron microscope (SEM). At the sample scale, celestine grains are responsible of an alpha signal, indicating that 226Ra is detectable in celestine from its alpha emissions. 226Ra distribution has also been investigated at the celestine grains/crystals scale the crystal/grain properties do not allow to decide if the distribution process is homogeneous or not, i.e. if there is a chemical zoning into the crystal/grain. The counting of alpha particles by autoradiography has been compared with the total activity of the 226Ra doped celestines by gamma counting (HPGe technique). This comparison was performed by standardizing the measured activities to the same celestine volume, which has been determined by performing a threshold on SEM grey level images to assess to the celestine surface and using Geant4 Monte Carlo simulation toolkit to assess to the emission depth of the particles in celestine. A very good linear correlation between gamma activity and alpha counting from autoradiographs is obtained for all the samples, demonstrating the ability of BeaQuant™ to quantify 226Ra in any points of the millimetric section samples, at a resolution of 20 μm. In this work, we have studied sorption of 137Сs and 90Sr radionuclides from seawater under batch conditions by ferrocyanide sorbents based on hydrated titanium and zirconium dioxides (Т-35, NPF-HTD), clinoptilolite and glauconite (NPF-GL, NPF-CL) natural aluminosilicates, zirconium phosphate (T-3A), modified hydrated titanium dioxide (T-3K) as well as by manganese dioxide based on hydrated titanium dioxide (MD-HTD). Isotherms of sorption and dependences of cesium distribution coefficients on salt content and calcium concentration were obtained. Distribution coefficients of cesium and strontium were calculated. Stability of spent sorbents against radionuclides leaching was studied in from the point of view of their further treatment. The NPF-GL and NPF-HTD sorbents are recommended for treatment of seawater-based liquid radioactive waste with various salinity; these sorbents possess high distribution coefficients of cesium 104 and 105 ml/g even at the salinity of waste as high as 100 g L-1. Distribution coefficients of strontium from seawater were (1.0-1.9)·102 ml/g for all sorbents that is conditioned by the presence of colloidal species of strontium (34 ± 7%) in the simulated seawater. Capacities of the sorbents for strontium varied within 200-310 mg/g. The sorbents strongly retain adsorbed radionuclides the total percentage of leaching for 28 days was 4.4%, 2.2% and 3.1% for 137Cs leaching from the NPF-HTD, T-35 and T-3A sorbents respectively and 10.7% for 90Sr leaching from the NPF-CL sorbent. Systematic monitoring of environmental radionuclides with the aim of early warning in emergency situations in Federation of Bosnia and Herzegovina (FB&H) was established in 2004. Environmental radiation monitoring network includes six automatic monitoring stations over the FB&H territory. This paper deals with the first study of ambient dose equivalent rates collected over the period of 2012-2017 with the main objective to investigate the temporal and spatial variations in the outdoor background radiation. The correlation analysis between the continuously acquired gamma dose rates and the simultaneous meteorological records on
