Compatibility of fuel-element cladding materials with gallium-containing uranium and uranium–plutonium oxide fuel

Powders of uranium oxide powder and mixed fuel containing 5 and 20 mass % plutonium and 0.4 and 5 mass % gallium were prepared by coprecipitation from nitrate solutions. Pelleted samples for testing were made by cold pressing and sintering. The compatibility of uranium oxide fuel and mixed uranium–plutonium fuel, containing 0.4 and 5 mass % gallium, with the zirconium alloy E-110 at 400 and 500°C and ChS-68 corrosion-resistant steel at 650 and 750°C over periods of 1000, 2000, and 3000 h was investigated. Metallographic and x-ray spectral microprobe analyses of diffusion samples established that there was no interaction and penetration of gallium into the zirconium alloy and steel. In addition, the diffusion coefficient of metallic gallium in zirconium alloy and the distribution of the elements on interaction of gallium with ChS-68 steel were evaluated.     

Correlation between induced embryo toxicity and absorption dose of enriched uranium in testes

ＣｏｒｒｅｌａｔｉｏｎｂｅｔｗｅｅｎｉｎｄｕｃｅｄｅｍｂｒｙｏｔｏｘｉｃｉｔｙａｎｄａｂｓｏｒｐｔｉｏｎｄｏｓｅｏｆｅｎｒｉｃｈｅｄｕｒａｎｉｕｍｉｎｔｅｓｔｅｓＺｈｕＳｈｏｕ－Ｐｅｎｇ（朱寿彭）ａｎｄＬｕｎＭｉｎｇ－Ｙｕｅ（伦明跃）（ＳｕｚｈｏｕＭ...     

Transient and stability analysis of a BWR core with thorium–uranium fuel

The kinetic response of a boiling water reactor (BWR) equilibrium core using thorium as a nuclear material, in an integrated blanket–seed assembly, is presented in this work. Additionally an in-house code was developed to evaluate this core under steady state and transient conditions including a stability analysis. The code has two modules: (a) the time domain module for transient analysis and (b) the frequency domain module for stability analysis. The thermal–hydraulic process is modeled by a set of five equations, considering no homogeneous flow with drift-flux approximation and non-equilibrium thermodynamic. The neutronic process is calculated with a point kinetics model. Typical BWR reactivity effects are considered: void fraction, fuel temperature, moderator temperature and control rod density. Collapsed parameters were included in the code to represent the core using an average fuel channel. For the stability analysis, in the frequency domain, the transfer function is determined by applying Laplace-transforming to the calculated pressure drop perturbations in each of the considered regions where a constant total pressure drop was considered. The transfer function was used to study the system response in the frequency domain when an inlet flow perturbation is applied. The results show that the neutronic behavior of the core with thorium uranium fuel is similar to a UO₂ core, even during transient conditions. The stability and transient analysis show that the thorium–uranium fuel can be operated safely in current BWRs.     

Coextraction of uranium(VI) from nitric acid solutions by N,N-diethyldecanamide and TBP

Ｃｏｅｘｔｒａｃｔｉｏｎｏｆｕｒａｎｉｕｍ（ＶＩ）ｆｒｏｍｎｉｔｒｉｃａｃｉｄｓｏｌｕｔｉｏｎｓｂｙＮ，ＮｄｉｅｔｈｙｌｄｅｃａｎａｍｉｄｅａｎｄＴＢＰＳｕｎＧｕｏＸｉｎ，ＷａｎｇＹｏｕＳｈａｏ，ＹａｎｇＹａｎＺｈａｏ，ＢａｏＢｏＲｏｎｇ...     

The dodecyltolylsulfoxide extraction of uranium （VI）

１ＩｎｔｒｏｄｕｃｔｉｏｎＴｒｉｎｂｕｔｙｌｐｈｏｓｐｈａｔｅ（ＴＢＰ）ｈａｓｂｅｎｕｓｅｄｆｏｒｓｅｖｅｒａｌｄｅｃａｄｅｓａｓｔｈｅｍｏｓｔｓｕｃｅｓｆｕｌｅｘｔｒａｃｔａｎｔｆｏｒｒｅｃｏｖｅｒｙｏｆｕｒａｎｉｕｍｆｒｏｍｓｐｅｎｔｎｕｃｌ...     

Solvent extraction of uranium(VI) and europium(III) from nitrate media by picolinamide

The solvent extraction of uranium(VI) and europium(III) from nitric acid solution was studied with pi- colinamide dissolved in ethylene dichloride. The distribution ratios of U(VI) and Eu(III) as a function of aqueous HNO3 concentration , extractant concentration in organic phase and temperature as well as the salting-out agent con- centration have been measured. The experiment results show that picolinamide has higher extractability for U(VI) than for Eu(III). The composi…     

Solvent extraction of uranium(Ⅵ)and europium(Ⅲ)from nitrate media by picolinamide

The solvent extraction of uranium(Ⅵ) and europium(Ⅲ) from nitric acid solution was studied with picolinamide dissolved in ethylene dichloride. The distribution ratios of U(Ⅵ) and Eu(Ⅲ) as a function of aqueous HNO3 concentration, extractant concentration in organic phase and temperature as well as the salting-out agent concentration have been measured. The experiment results show that picolinamide has higher extractability for U(Ⅵ1)than for Eu(Ⅲ). The composition of extracted species, equilibrium constants and enthalpies of extraction reaction have also been presented.     

Branched fibrous amidoxime adsorbent with ultrafast adsorption rate and high amidoxime utilization for uranium extraction from seawater

Direct collection of uranium from low uranium systems via adsorption remains challenging.Fibrous sorbent materials with amidoxime (AO) groups are promising adsorbents for uranium extraction from seawater.However,low AO adsorption group utilization remains an issue.We herein fabricated a branched structure containing AO groups on polypropylene/polyethylene spun-laced nonwoven (PP/PE SNW) fibers using grafting polymerization induced by radiation (RIGP) to improve AO utilization.The chemical struct...     

Solvent extraction of uranium（Ⅵ） and europium（Ⅲ） from nitrate media by picolinamide

The solvent extraction of uranium(Ⅵ) and europium(Ⅲ) from nitric acid solution was studied with picolinamide dissolved in ethylene dichloride. The distribution ratios of U(Ⅵ) and Eu(Ⅲ) as a function of aqueous HNO3 concentration, extractant concentration in organic phase and temperature as well as the salting-out agent concentration have been measured. The experiment results show that picolinamide has higher extractability for U(Ⅵ)than for Eu(Ⅲ). The composition of extracted species, equilibrium constants and enthalpies of extraction reaction have also been presented.     

Efficient and selective extraction of uranium from seawater based on a novel pulsed liquid chromatography radionuclide separation method

The novel pulsed liquid chromatography radionuclide separation method presented here provides a new and promising strategy for the extraction of uranium from seawater. In this study, a new chromatographic separation method was proposed, and a pulsed nuclide automated separation device was developed, alongside a new chromatographic column. The length of this chromatographic column was 10 m, with an internal warp of 3 mm and a packing size of 1 mm, while the total separation units of the column re...     

Nuclear and thermal–hydraulic characteristics for an LMR core fueled with 20% enriched uranium metallic fuel

As a part of the core design development of KALIMER (150 MWe), the KALIMER core was initially designed with 20% enriched uranium metallic fuel. In this core design, the primary emphasis was given to realize the metallic fueled core design to meet the specific design requirements; 20% and below uranium enrichment and a minimum fuel cycle length of one year. The core was defined by a radially homogeneous core configuration incorporated with several passive design features to give inherent passive means of negative reactivity insertion. The core nuclear performance based on a once-through equilibrium fuel cycle scenario shows that the core has an average breeding ratio of 0.67 and maximum discharge burnup of 47.3 MWD/kg. When comparing with conventional plutonium metallic fueled cores of the same power level, the present uranium metallic fueled core has a lower power density due to its increased physical core size. The negative sodium void reactivity over the core shows a beneficial potential to assure inherent safety characteristics. The transition from the uranium startup to equilibrium cycle is feasible without any design change. Core nuclear performance characteristics in the present core design are attributed to the specific design requirements of enrichment restriction and fuel cycle length.     

Burnup characteristics and fuel cycle economics of mixed uranium–thorium fuel in a simplified small pebble bed reactor

The limitation of natural uranium resources and the improvement of economic values of nuclear reactors are important issues to be solved in the future development of these reactors. In our previous study, we presented an innovative design for simplifying a pebble bed reactor, and the optimization of this design showed that burnup values could be increased and natural uranium uses could be reduced. The purposes of the current study were to design a simplified pebble bed reactor by removing the unloading device from the reactor system and to further optimize the burnup characteristics of this reactor with a peu à peu fuel-loading scheme by introducing thorium in the fuel configuration as a fertile material. Another goal was to optimize the fuel composition so that the system could achieve even better burnup characteristics and use scarce uranium resources more efficiently. Using a specially developed computer code, we analyzed and optimized the performance of a 110-MWt simplified pebble bed reactor using a peu à peu fuel-loading scheme. An optimized design using 30% of fertile thorium mixed with uranium fuel with 15% ²³⁵U enrichment and a 7% packing fraction calculated to achieve a high burnup of 140 GWD/T for more than 21 years' operation time that could save 13 to 33% of natural uranium use compared with the savings noted in our previous study. Neutronic, burnup and fuel economic analysis for this optimized design are discussed in this study.     

Sorption of uranium(Ⅵ) from aqueous solutions by DEEA organovolcanic: isotherms,kinetic and thermodynamic studies

The sorption of the uranium(VI) ions from aqueous solutions by diethylethanolammonium organovolcanics(Kula-TURKEY) was investigated under different experimental conditions. DEEA was used to modify the surface of basaltic volcanics. The characteristic of basaltic volcanic was analyzed by XRF, SEM–EDS, FTIR, and XRD. The BET surface areas of unmodified volcanics and DEEA-modified volcanics were found as 2.265 and3.689 m~2/g, respectively. The volcanic samples were treated by using different concentrations of DEEA. The adsorption of U(VI) on natural and modified volcanics was examined as a function of the contact time, initial p H of the solution, initial U(VI) concentration, and temperature.Langmuir, Freundlich, and D–R adsorption isotherms were used to describe the adsorption. While examining the adsorption percentage and distribution coefficient, these values for unmodified volcanics were found to be25% ± 0.76 and 10.08 m L/g, while the values for the DEEA-modified volcanics were 88% ± 1.04 and 220 m L/g, respectively. The pseudo-first-order and pseudo-secondorder kinetic models were used to describe the kinetic data.In this study, it can be seen that the adsorption process is suitable for the pseudo-second-order kinetic model. Various thermodynamic parameters(ΔG°, ΔH°, and ΔS°) were calculated with the thermodynamic distribution coefficients obtained at different temperatures. The sorption process was a chemical adsorption process. The results indicated that the processes are spontaneous and endothermic.     

Interaction between uranium and humic acid （Ⅱ）： complexation, precipitation and migration behavior of U（Ⅵ） in the presence of humic substances

The complexation, precipitation, and migration behavior of uranium in the presence of humic acid (HA) or fulvic acid (FA) were investigated by cation exchange, ultrafiltration and dynamic experiment, respectively. The results showed that (i) complex equilibrium between the uranium and humic substances was achieved at approximately 72 h, (ii) the coordination number varied from 1:1 to 1:2 ( U(Ⅵ) : humic acid) as pH increased from 3 to 6; and (iii) , while the complex stability constant decreased when temperature increased, but increased with pH value. We found that the precipitation of uranyl could only be observed in presence of HA, and the precipitation was influenced by conditions, such as pH, uranium concentration, temperature, and the HA concentration. The maximum precipitation proportion up to 60% could be achieved in the condition of 40 mg/L HA solution at pH 6. We further observed that the migration behavior of uranium in soil in the presence of humic acid (HA) or fulvic acid (FA) was different from that in the presence of inorganic colloid, and the effect of humic substances (HS) was limited.     

Interaction between uranium and humic acid (Ⅰ): Adsorption behaviors of U(Ⅵ) in soil humic acids

The adsorption behaviors of uranium on three soil humic acids (HAs), which were extracted from soils of different depths at the same site, were investigated under various experimental conditions. The adsorption results showed that U(Ⅵ) in solutions can be adsorbed by the three soil HAs, with the order of FHA (HA from 5 m depth of soil) ＞SHA (HA from the surface) ＞THA (HA from 10 m depth of soil) for adsorption efficiency in each desirable condition, and the adsorption reached equilibrium in about 240 min. Although the maximum adsorption efficiency was adsorption could be described with Langmiur isotherm or Freundlich isotherm equation. The L/S (liquid/solid, mL/g)ratio and pH were important factors influencing the adsorption in our adsorption system besides uranium concentration. The adsorption efficiency decreased with the increase of the L/S ratio and pH at the pH range of 2.0-3.0 for SHA and THA or 2.5 - 6.0 for FHA. However, no significant difference in adsorption of U(Ⅵ) was observed at the experimental temperature. All the results implied that humic substances have different characteristics in samples even collected at the same site.     

The synergic extraction of uranium(Ⅵ) with tri-n-butyl phosphate (TBP) and petroleum sulfoxides(PSO)/benzene

1 INTRODUCTIONThe solvent extraction method has been one of the imPortant tecdriques fOr concen-trating and purifying Of urboum, tri-n-butyl phosphate (TBP) has been used for severaldecades as the most successful extractant fOr recovery of uxanium from spent nuclearfuel. Sulfeddes have been considered as potential extractants for use in nuclear aPplica-tions fOr many years.[1~5] Petroleum suifeddes (PSO) obtained from petroleum retringare widely emPloyed due to their good solubility,…     

Interaction between uranium and humic acid （Ⅰ）： Adsorption behaviors of U（Ⅵ） in soil humic acids

The adsorption behaviors of uranium on three soil humic acids (HAs), which were extracted from soils of different depths at the same site, were investigated under various experimental conditions. The adsorption results showed that U(Ⅵ) in solutions can be adsorbed by the three soil HAs, with the order of FHA (HA from 5 m depth of soil) >SHA (HA from the surface) >THA (HA from 10 m depth of soil) for adsorption efficiency in each desirable condition, and the adsorption reached equilibrium in about 240 min. Although the maximum adsorption efficiency was achieved at a suitable uranium concentration (10 mg·L-1 U(Ⅵ) for SHA and THA, 20 mg·L-1 U(Ⅵ) for FHA), the adsorption could be described with Langmiur isotherm or Freundlich isotherm equation. The L/S (liquid/solid, mL/g) ratio and pH were important factors influencing the adsorption in our adsorption system besides uranium concentration. The adsorption efficiency decreased with the increase of the L/S ratio and pH at the pH range of 2.0-3.0 for SHA and THA or 2.5-6.0 for FHA. However, no significant difference in adsorption of U(Ⅵ) was observed at the experimental temperature. All the results implied that humic substances have different characteristics in samples even collected at the same site.