Studies of the rate of migration of radiocesium in some types of soils of Eastern Poland

The activity of Cs-137 and Cs-134 in some types of soils of Eastern Poland was studied. The contribution of Cs-137 from post-Chernobyl fall-out as a function of depth in the soil profiles was calculated from the Cs-134:Cs-137 activity ratio taken from the literature just after the Chernobyl accident. Such information makes it possible to calculate the rate of vertical migration of radiocesium in various types of soils. The rate of the post-Chernobyl Cs-137 migration was found to exceed the rate of migration of Cs-137 from experimental nuclear explosions in the atmosphere. Cs-137 from the Chernobyl accident was found in a layer of soil a few cms thick in most of the soils which were examined. The contribution of post-Chernobyl radiocesium to the total contamination of the surface layer (0–5 cm) with cesium was ≈77%.     

Hydrothermal synthesis and spark plasma sintering of NaY zeolite as solid-state matrices for cesium-137 immobilization

Hydrothermal synthesis of NaY-type zeolite was carried out and the effect of temperature on the phase composition, crystal structure, textural characteristics, particle size and morphology, as well as sorption properties to Cs⁺ ions was studied. Solid-state matrices based on NaY zeolite the Faujasite structure containing 26.1 wt% cesium were obtained by spark plasma sintering (SPS) with high values of compressive strength (to 132.9 MPa) and Vickers microhardness to HV~ 698, Fracture toughness (K_1c) ~ 1.26 MPa m^1/2. The kinetics of ceramic matrices consolidation, phase composition and morphology using dilatometric studies, XRD, and SEM were studied. The thermogravimetric analysis shown the high thermal stability of the obtained samples up to 1300 °C. The high hydrolytic stability of CsAlSiO₄ ceramic was proven (leaching rate of 2.33 ×10^?8 g·cm^?2·day^?1 and cesium diffusion coefficient De 1.41 ×10^?13), which exceeds the requirements of GOST R 50926–96 and ISO 6961:1982 for solid-state matrices.     

Cs sorption to potential host rock of low-level radioactive waste repository in Taiwan: Experiments and numerical fitting study

A reliable performance assessment of radioactive waste repository depends on better knowledge of interactions between nuclides and geological substances. Numerical fitting of acquired experimental results by the surface complexation model enables us to interpret sorption behavior at molecular scale and thus to build a solid basis for simulation study. A lack of consensus on a standard set of assessment criteria (such as determination of sorption site concentration, reaction formula) during numerical fitting, on the other hand, makes lower case comparison between various studies difficult. In this study we explored the sorption of cesium to argillite by conducting experiments under different pH and solid/liquid ratio (s/l) with two specific initial Cs concentrations (100 mg/L, 7.5 × 10⁻⁴ mol/L and 0.01 mg/L, 7.5 × 10⁻⁸ mol/L). After this, numerical fitting was performed, focusing on assessment criteria and their consequences. It was found that both ion exchange and electrostatic interactions governed Cs sorption on argillite. At higher initial Cs concentration the Cs sorption showed an increasing dependence on pH as the solid/liquid ratio was lowered. In contrast at trace Cs levels, the Cs sorption was neither s/l dependent nor pH sensitive. It is therefore proposed that ion exchange mechanism dominates Cs sorption when the concentration of surface sorption site exceeds that of Cs, whereas surface complexation is attributed to Cs uptake under alkaline environments. Numerical fitting was conducted using two different strategies to determine concentration of surface sorption sites: the clay model (based on the cation exchange capacity plus surface titration results) and the iron oxide model (where the concentration of sorption sites is proportional to the surface area of argillite). It was found that the clay model led to better fitting than the iron oxide model, which is attributed to more amenable sorption sites (two specific sorption sites along with larger site density) when using clay model. Moreover, increasing s/l ratio would produce more sorption sites, which helps to suppress the impact of heterogeneous surface on Cs sorption behavior under high pH environments.     

Cesium Removal Demonstration Using Selected Actual Waste Samples from the Hanford Reservation Tank Farm

Abstract

Approximately 40 million curies of Cs‐137 are currently contained in High Level Waste stored in 177 underground storage tanks at the Hanford Nuclear Reservation near Richland, Washington. A series of actual waste, small‐scale column tests were performed to evaluate the performance of a selected ion exchange resin for cesium removal from a range of planned feed streams. These tests demonstrated that the selected cationic resin–SuperLig 644^®‐has more than adequate resin capacity to treat each of three potential feed streams. Furthermore, tests indicate an acceptable mass transfer zone for each of the three types of feed material, and that the elution of the resin can be accommodated within the design criteria for the proposed Waste Treatment Plant.     

长庆油田质量安全环保巡察实践

随着电力业务的不断扩展,勘测积累了大量的工程相关资料,目前大多存储分散,查询调用较为烦琐,再次利用率也非常低。针对电力勘测数据的特点,通过对开源JavaSctipt库和Cesium三维可视化关键技术的研究,设计了一套包含二、三维数据录入、三维可视化展示,数据查询、分析利用以及数据库管理的电力工程数据管理平台,为提高勘测数据管理效率,充分挖掘利用已有数据资源提供信息技术支持。     

Cesium salt of a heteropolyacid in nanotubular channels and on the external surface of SBA-15 crystals: preparation and performance as acidic catalysts

The Cs-salt of heteropolyacid with stoichiometry Cs_2.5H_0.5PW₁₂O₄₀ (CsHPW) was deposited selectively at the external surface of the SBA-15 silica microcrystals, inside its mesoporous channels and simultaneously at both location modes. The structure, texture and performance of these CsHPW/SBA-15 composites were compared with that of a reference bulk salt of the same composition. Location of CsHPW salt on the external surface of SBA-15 microcrystals leads to disintegration of its agglomerates increasing acidity of the catalytic phase. A novel preparation strategy consisting of grafting the basic Cs-species at the internal pores surface of SBA-15 stabilized the CsHPW phase inside the channels in form of 5–8 nm nanocrystals at 30–70 wt.% loadings. The catalytic tests demonstrated that insertion of the CsHPW catalytic phase inside the nanotubular channels of SBA-15 in combination with location of an additional amount of this phase at the external surface of SBA-15 microcrystals allows to increase the specific activity of this phase in MTBE synthesis, propionylation of anisole and alkylation of catechol with t-butanol by a factor of 1.5–3. This level of specific activity in combination with high total loading of catalytic phase >60 wt.% permit to get composite catalytic materials with catalytic activity higher by a factor of 1.2–1.5 with respect to the bulk CsHPW catalyst and stabilizing the catalytic phase against colloidization in polar media.     

凹凸棒石粘土对中低放核素Sr、Cs的吸附研究

通过实验研究 ,讨论了经不同方法改性处理的凹凸棒石粘土对锶铯的吸附作用。研究表明凹凸棒石粘土对铯的吸附能力优于锶。特别是经改性剂处理的凹凸棒石粘土 ,在碱性、氧化条件下对锶铯的吸附更为显著     

Investigation of Cs(I) and Sr(II) removal using nanoporous bentonite

ABSTRACT

Bentonites are types of clays made up the dominant constituent of montmorillonite. Four types of nano-porous and nano-structured commercial bentonite clays were studied in detail for their physicochemical and mineralogical properties vs. Cs and Sr adsorption. The instrumental analyses to study samples were X-ray diffraction (XRD), X-ray fluorescence (XRF), Brunauer–Emmett–Teller (BET) surface area measurements, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and thermogravimetry (TG). The XRF and peaks of XRD patterns at 2θ?=?8, 19.9, 35, 55, and 62 clearly indicated that the main component of the bentonite samples was montmorillonite. The BET analysis showed that B1 has the highest specific surface area among the other samples which its single and multiple point BET surface area were equal to 84.85 and 85.94?m²?g^?1, respectively. These values represents the amount of montmorillonite and adsorption capacity of samples. The physicochemical, structural and morphological characteristics of different samples were investigated through instrumental analysis. The results of separation processes of Cs(I) and Sr(II) showed 59.75 and 45.5% adsorption capacities for B3 and B2 which were the highest values among the others. The results lead to the conclusion that samples B3 had a good adsorption capacity to remove Cs(I) and Sr(II).     

重稀碱金属铷和铯的分离分析方法进展

近年来稀碱金属铷、铯的研究与应用越来越引起人们的关注 ,因而对其分析方法也提出了更高的要求。根据有关文献对铷和铯的各种分离、分析方法的研究状况、进展及发展趋势进行了分析和评述。内容主要涉及铷、铯分离中的一些选择性较好的吸附试剂、萃取试剂的应用 ,及分析方法中适用于环境、生物和食品等样品中微量或痕量铷、铯分析的仪器分析方法 (包括原子吸收光谱法和原子发射光谱法等已经发展得较为完善且得到了广泛应用的经典方法 ,并介绍了一些近年来发展较快的仪器分析方法 ,包括电感耦合等离子体质谱法、X射线荧光光谱分析、离子选择性电极法等 )。引用文献 6 9篇。