1,721,024 research outputs found
Drone-borne dosimetry in a radiological or nuclear scenario
No full textThis paper describes the drone-borne dosimetry performed in two separate case studies. Two drone measurements were performed using a reference dose-rate detector measuring the ambient dose equivalent rate. A first flight was used to obtain reference measurements using a cesium-137 point source and flying at multiple speeds and different heights. A second flight was performed above the D1 radium storage of Umicore in Olen, Belgium. The main goal of this flight was to perform a scanning pattern over the area to create a dose-rate map. After the flights, we used historic measurements and a dose-rate model verified by Monte Carlo simulations using Penelope (2018) to verify the dose-rates measurements performed by the drone. Finally, we used the findings from both flights to provide recommendations regarding drone measurements using dose-rate detectors
Radiological Surveillance Using a Fixed-Wing UAV Platform
No full textA drone–detector system was designed, developed, and tested for radiological monitoring. The system was tailored to perform measurements during the threat, release, and post-release phases of a nuclear or radiological event. This allows the surveillance of large areas, with an autonomy of up to 12 h, in a large range of altitudes above ground level. The detector system was optimized for gamma spectroscopy, taking into account the available payload for maximum endurance and maximum detection efficiency using ‘PENELOPE (2018)’ Monte Carlo simulations. A generic methodology was used to derive quantitative information on radioactivity levels from the raw measured gamma-ray spectra at different altitudes. Based on the methodology, it was demonstrated that the drone–detector system can measure the concentration of potassium-40 (K-40) that is naturally present in the soil. These measurements complied within 30% of the soil sampling results taking into account the uncertainties. The functioning of the system was tested during test flights, which demonstrated that radionuclide identification and quantification of radioactivity concentrations are possible
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Investigation of xenon adsorption in three types of porous materials
No full textThe recovery of xenon from atmospheric air, based on highly efficient and selective adsorption, could replace the current cost-intensive cryogenic distillation generally used for xenon production. In addition, adsorption improvements for the measurement of ultra-low levels of radioactive xenon in the atmosphere could increase the capability of the verification system for the Comprehensive Nuclear-Test-Ban Treaty (CTBT). In the same context, enhanced radioactive xenon trapping systems at civilian nuclear installations could also improve the verification capability, as this would further reduce the atmospheric radioactive xenon background.
Activated carbon has been used for more than 60 years in the nuclear industry to recover radioactive xenon from gaseous effluents. About 20 years ago, researchers have demonstrated that some silver-exchanged zeolites had a higher Xe adsorption capacity at low Xe-partial pressures. The lack of knowledge on the durability of these zeolites did not yet allow their use with highly radioactive gas streams. More recently, some metal-organic frameworks have been demonstrated to be quite selective for xenon over other gas components, which could open a new opportunity in these fields. Ideally, adsorbents that are capable of trapping large amounts of xenon whilst being highly selective for xenon are looked for. In addition, these adsorbents should be durable against multiple temperature swing adsorption cycles as well as against severe irradiation.
In this poster, the measurement of xenon breakthrough curves over a range of conditions, used for the investigation of the Xe adsorption properties, will be presented and the results obtained on the three types of adsorbents will be discussed. Other characterization techniques (e.g. liquid nitrogen adsorption and thermal gravimetric analysis) used to support such research, through the identification of promising materials and to investigate their durability, will be addressed
Application of silver-exchanged zeolite for the mitigation of civilian radioxenon releases
No full textThe radioxenon releases from civilian nuclear installations are significantly affecting the International Monitoring System (IMS), which is being deployed for the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). These civilian radioxenon releases are disturbing and limiting the detection capability of the noble gas component of the IMS for CTBT-related events. Substantial reductions of civilian radioxenon releases would significantly improve the detection capability of the noble gas component of the IMS.
For a long time, activated carbon has been the standard for trapping radioxenon from gaseous effluents in the nuclear industry. In this work, we demonstrate the potential of silver-exchanged zeolites for replacing activated carbon and providing a higher radioxenon trapping efficiency. For this purpose, three activated carbons and five silver-exchanged zeolites are compared through their Xe adsorption properties in helium - and nitrogen bulk gas. The effect of moisture in the inlet gas stream on the Xe adsorption properties is considered as well. The most promising silver-exchanged zeolite is then further investigated for its practical application by studying the effect of column geometry, flow rate and temperature. Finally, the durability of this adsorbent against irradiation and desorption/adsorption cycles is examined for its application in the nuclear industry.
Recently in the literature, some metal-organic frameworks have been demonstrated to be quite selective for the adsorption of xenon over other gas components. The Xe adsorption properties measured on two metal-organic framework materials will be presented to put their potential application for radioxenon mitigation into perspective
Experimental investigation of adsorption materials for the mitigation of civilian radioxenon releases
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