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Origins
Published in Douglas S. McGregor, J. Kenneth Shultis, Radiation Detection, 2020
Douglas S. McGregor, J. Kenneth Shultis
The observations and findings of Becquerel caught the interests of Pierre and Marie Curie, both chemists by education (see Fig. 1.8). Marie began studying under Becquerel, and began a systematic investigation of the known elements to determine if other materials emitted energetic rays similar to those from uranium. While studying pitchblende, an uranium ore containing various oxides, thorium, and other rare earth elements, she found that thorium and thorium compounds also emitted energetic rays. Marie is generallycredited with recommending the name radioactivity3 to describe these energetic emissions. Marie quickly reported these findings, only to learn that German physicist Gerhard Schmidt had published similar findings on thorium only two months earlier. However, of genuine interest in Curie’s work was the observation that the pitchblende, after removing the uranium, was more radioactive than the uranium. The Curies thus deduced correctly that another radioactive element must be present.
Metal Recovery Processes
Published in C. K. Gupta, T. K. Mukherjee, Hydrometallurgy in Extraction Processes, 2017
The acid route for monazite sand processing involves digestion with concentrated H2SO4, followed by water leaching to yield monazite sulfate solution. Thorium can be precipitated from such solution either as phosphate or oxalate to form thorium concentrate, which is further treated for the production of high-purity thorium compounds. The phosphate precipitation91 happens to be the most common way of separating thorium from the sulfate solution, which contains Th, U, RE, sulfate, and phosphate ions. Selective precipitation of thorium phosphate is possible at controlled acidity according to the following reaction: () Th4++2H2PO4−→ThP2O7+H2O+2H+
Rare earths of the Murmansk Region, NW Russia: minerals, extraction technologies and value
Published in Applied Earth Science, 2023
Andrey O. Kalashnikov, Nataly G. Konopleva, Konstantin P. Danilin
contains Ti and REE as an economic component. REE extraction technological processes of perovskite are also developed only at laboratory scale. However, complex technologies for treatment perovskite have already been developed for the Afrikanda deposit. They are based on the production of pigment titanium dioxide, and REE as the byproducts (Krysenko et al. 2016; Krysenko et al. 2016). The process of beneficiation of perovskite ore by flotation method with phosphoric acid has also been known for a long time (Bulatovic and Wyslouzil 1999). The main issue of pervoskite processing is utilisation of radioactive thorium compounds. Nevertheless, there are some techniques for thorium utilisation (e.g. extraction of thorium by chloride solutions with tributyl phosphate) (Maiorov et al. 2004, 2007).
Structural phase stability, mechanical and anharmonic properties of actinide sulfides: a high pressure study with the role of temperature
Published in Journal of Coordination Chemistry, 2018
The phase transition properties of uranium chalcogenides and thorium chalcogenides have been studied widely using the different theoretical methods and experimental methods. The majority of the compounds of uranium and thorium compounds go through a structural phase transition from the rock salt structure to cesium chloride structure under high pressure i.e. their coordination number increases from 6 to 8 [3]. Shrivastava et al.[4] used two-body potential to study the phase transition properties of uranium monochalcogenides. Jha and Sanyal [5] employed rigid ion model (RIM) and shell model (SM) with two-body interaction to study the phonon properties of uranium compounds. The models used by Jha and Sanyal [5] and Shrivastava et al. [4] are inadequate for explaining the Cauchy violation. Bihan et al. [6] reported that the transition pressure of US is 80 GPa in a silicon oil medium. Varshney et al. [7] reported the structural phase transition of uranium monochalcogenides using an effective interionic potential. Limited report was given by Varshney et al. [7] regarding the bulk properties of these compounds. Using the X-ray diffraction technique, Benedict et al. [8] reported the transition pressure of ThS at 23–33 GPa. Anayas et al. [3] reported the phonon spectra of thorium pnictides and chalcogenides at high pressure using rigid ion and breathing shell models, which do not explain the Cauchy violation. Raju [9] reported the elastic behavior of thorium compounds theoretically (ThS and ThSe) using the force shell model.
The Impacts of Liquid Metal Plasma-Facing Components on Fusion Reactor Safety and Tritium Management
Published in Fusion Science and Technology, 2019
Paul W. Humrickhouse, Brad J. Merrill, Su-Jong Yoon, Lee C. Cadwallader
As mentioned above, in some cases the chemical hazard can be greater than the radiological hazard. Reyes et al.17 examined mercury and lead target material releases from an inertial fusion facility and determined that if TEEL-2 were used as the limiting concentration, then the concentrations that would yield an acceptable radiological dose would exceed the chemical safety requirements by a factor of 3 to 5. The conclusion was that radiological hazards dominate the risks of fusion facilities, but chemical hazards must also be considered to provide a complete public safety assessment. The DOE has also stated that mixed (radioactive and chemically toxic) releases may need to consider chemical toxicity. Chemical toxicity, rather than radioactivity, drives exposure limits for 238U, and the DOE chemical exposure handbook21 notes that for enriched uranium, the chemical toxicity concern becomes dominant as the nominal 235U enrichment decreases through the range from about 16% to 5%. The DOE has also commented on chemical safety aspects of uranium and thorium compounds due to their relatively high solubility in body fluids (carbonate, nitrates, fluorides, sulfates).21 In general, the approach to assess public risks from radioactive and toxic mixed material releases is to first examine radiation exposure risks of the released substance, then examine the chemical exposure risks of the released substance as a separate exposure, and then report both results. Separate reporting assumes the two types of exposures do not aggravate each other, which may not always be correct. Evaluation of chemical exposures has uncertainty because of the ways chemicals interact with human biology. Mixed exposures must be treated on a case-by-case basis. The EPA has some guidance on aggregating effects of multichemical exposures.22