Pyrochemistry is a promising technology that can provide benefits for the safe reprocessing of relatively fresh spent nuclear fuel with a short storage time (3–5 years). The radioactive waste emanating from this process is an electrolyte (LiCl–KCl) mixture with fission products included. Such wastes are rarely immobilized through common matrices such as cement and glass. In this study, samples of ceramic materials, based on natural bentonite clay, were studied as matrices for radioactive waste in the form of LiCl–KCl eutectic. The phase composition of the samples, and their mechanical, hydrolytic, and radiation resistance were characterized. The possibility of using bentonite clay as a material for immobilizing high-level waste arising from pyrochemical processing of spent nuclear fuel is further discussed in this paper.
Immobilization of spent electrolyte–radioactive waste (RW) generated during the pyrochemical processing of mixed nitride uranium–plutonium spent nuclear fuel is an acute task for further development of the closed nuclear fuel cycle with fast neutron reactors. The electrolyte is a mixture of chloride salts that cannot be immobilized directly in conventional cement or glass matrix. In this work, a low-temperature magnesium potassium phosphate (MPP) matrix and two types of high-temperature matrices (sodium aluminoironphosphate (NAFP) glass and ceramics based on bentonite clay) were synthesized. Two systems (Li0.4K0.28La0.08Cs0.016Sr0.016Ba0.016Cl and Li0.56K0.40Cs0.02Sr0.02Cl) were used as spent electrolyte imitators. The phase composition and structure of obtained materials were studied by XRD and SEM-EDS methods. The differential leaching rate of Cs from MPP compound and ceramic based on bentonite clay was about 10−5 g/(cm2·day), and the rate of Na from NAFP glass was about 10−6 g/(cm2·day). The rate of 239Pu from MPP compound (leaching at 25 °C) and NAFP glass (leaching at 90 °C) was about 10−6 and 10−7 g/(cm2·day), respectively. All the synthesized materials demonstrated high hydrolytic, mechanical compression strength (40–50 MPa) even after thermal (up to 450 °C) and irradiation (up to 109 Gy) tests. The characteristics of the studied matrices correspond to the current requirements to immobilized high-level RW, that allow us to suggest these materials for industrial processing of the spent electrolyte.
Burn injury is a serious problem with high morbidity and mortality. Burn injury outcomes are the most important indicators of research results and an important criterion for decision making in clinical practice. The presence of dozens of prognostic techniques indicates the absence of an ideal model for predicting the outcome of burns, as evidenced by the need to validate them in each burn center. The use of prognosis models for clinical purposes allows you to determine the risk of mortality of an individual patient, that is, the severity of his condition. However, point scales do not allow to determine the severity of the condition of groups of patients. Moreover, the achievement of most of the stated goals of the forecast becomes impossible. A methodological error lies in the violation of the sequence of actions during the experiment. First of all, it is necessary to stratify research groups according to the severity of the condition, and only then study their characteristics. However, none of the known forecast models makes it possible to determine the severity of the condition of a group of patients, and, therefore, to stratify them for research purposes. Given the structure and methods of creating models of hope for multicenter randomized prospective studies, which are expected to improve their quality, are not justified. The criterion for creating the best model is its optimality, which allows forecasting to determine the severity of the condition in order to achieve maximum practical benefit. With its help, it becomes possible to plan experiments and solve real problems of combustiology. This model will allow you to create practical recommendations and standards for the treatment of burns.
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