Research Reactor Research Articles

Failure investigation and mitigation after experimental research reactor fuel plate deformation in an irradiation device

Failure investigation and mitigation after experimental research reactor fuel plate deformation in an irradiation device

Numerical and experimental study of shut-off rod assembly of a typical Indian research reactor under multi-support seismic excitation

Numerical and experimental study of shut-off rod assembly of a typical Indian research reactor under multi-support seismic excitation

Forced Dynamic Operation of Propylene Selective Oxidation to Acrolein on Bismuth-Molybdate Structured Catalysts

Forced dynamic operation (FDO) of selective oxidation of propylene to acrolein is evaluated on a structured alumina foam coated with a mixed metal oxide catalyst (bismuth molybdate-based). Reactor experiments examine feed composition modulation as a strategy to increase the yield of acrolein. At lower temperatures, separating the oxidant (O2) and reductant (C3H6) enhances propylene conversion and acrolein selectivity. Variation in the reaction-regeneration switching amplitude and frequency gives a 40% higher cycle-averaged acrolein yield compared to steady-state operation (SSO) for the same overall feed composition. The results suggest that FDO maintains a higher concentration of selective oxygen species during the propylene feed, while pre-oxidation of the catalyst maximizes the amount of selective oxygen species, leading to increased acrolein yield at the beginning of the reaction cycle. Experiments at lower temperature for both commercial promoted and in-house, unpromoted catalysts reveal both catalysts are most active and selective at their highest oxidation states.

Unraveling dolomite dissolution stoichiometry in circumneutral to alkaline pH environments

Abstract Examining carbonate dissolution kinetics at mineral-water interface is crucial to understand numerous environmental and geochemical processes, including global carbon cycling, CO2 sequestration in deep geological reservoirs, and trace elements release in terrestrial and aquatic environments. Here we explored the effect of circumneutral to alkaline pH solutions (pH 6–11) on dissolution kinetics of pure dolomite and Ca and Mg release stoichiometry in flow-through reactor experiments at 25 ± 1 °C. Results revealed that the dolomite dissolution rates obtained from effluent Ca and Mg concentrations (RCa and RMg in mol/cm2/s) were dependent on input solution pH and HCO3 − log activity. The pH dependence of dissolution rates showed two distinct trends, i.e., at circumneutral pH ranging between 6 and 8, the dissolution rate decreased with increasing pH, with minimum rate at pH 8. While in the highly alkaline pH range (pH 9–11), the dolomite dissolution rate increased with an increasing pH. Irrespective of the input pH, the dolomite dissolution rates indicated a reverse relationship with HCO3 − log activity, with the lowest dissolution rate (RCa = 3.80 × 10–12 mol/cm2/s) at pH 8 where HCO3 − log activity attained the highest value (− 3.957). The lower RCa and RMg obtained at pH 8 compared to all the other pH could possibly be attributed to an inhibition caused by high HCO3 − log activity in solution at this pH. Dolomite dissolution rates were non-stoichiometric at all the experimental pH values, showing higher preferential Ca over Mg release (RCa > RMg) whereas an opposite trend was observed at pH 8, with RCa < RMg at the steady state. Saturation index values calculated using geochemical speciation modelling were positive for Mg-bearing minerals (brucite, dolomite, artinite) at alkaline pH of 10–11, indicating favourable conditions for their precipitation under studied conditions. This study provides insights on the significance of log ion activities of HCO3 − and Me-OH+ under varying pH for elucidating the dissolution mechanism of dolomite in circumneutral to alkaline aqueous environments.

Co‐digestion of olive mill wastewater and municipal solid waste landfill leachate promotes medium‐chain fatty acids and hydrogen production

AbstractThe management of olive mill wastewater (OMWW) and municipal solid waste landfill leachate presents a significant challenge due to their high concentrations of organic matter and phenolic compounds. These substances complicate treatment processes, hinder their potential use in agriculture, and inhibit key biological processes such as acetogenesis and methanogenesis. Nonetheless, an urgent need remains to develop a sustainable solution for managing hazardous waste while generating valuable resources. This research hypothesizes that co‐digestion can enhance the production of medium‐chain fatty acids (MCFAs) and hydrogen (bioenergy), which are target molecules due to their wide range of applications. Several batch reactor experiments were conducted to investigate the co‐digestion of OMWW and landfill leachate at varying ratios, with and without the addition of ethanol as an electron donor. The results show 30% landfill leachate:70% OMWW, supplemented with ethanol, achieved the highest MCFA production, predominantly of hexanoic acid, along with significant hydrogen generation. Finally, co‐digestion of OMWW and landfill leachate demonstrated significant potential for producing both MCFAs and hydrogen, offering a solution to the environmental issues posed by these effluents and promoting the circular economy.

Selective alkaline leaching of vanadium, chromium and aluminium from fly ash residue

ABSTRACT Vanadium, chromium and aluminium have many applications in several fields. For instance, vanadium alloys are considered a promising candidate for low activation structural material for fusion reactors and aerospace applications while aluminium is used in the reactor tanks of research reactors, core grids, neutron beam tubes, etc. Recently, nuclear fuel vendors have been researching and testing fuel with the outside of the zirconium alloy cladding coated with a thin layer of chromium. Fly ash resulting from power plants contains appreciable amounts of those metals. To minimise the environmental impact due to land disposal of fly ash, the removal of vanadium, chromium and aluminium was investigated using an alkaline leaching process, followed by a second step of metal recovery from leachates involving extraction, stripping and precipitation. Sodium hydroxide was chosen as a selective leaching agent for the metals under study. The best conditions for recovery were optimised based on the results obtained involving the study of different factors affecting the process. At room temperature and solid/liquid ratio of 1/10, the respective leaching percentages of V, Al and Cr reached maximum values of 70%, 48% and 36% after 2 h of continuous leaching. Combining extraction, stripping and precipitation methods enabled the recovery percents of V, Cr and Al to be 96.2%, 90.5% and 84.0%, respectively.

Role of the BOR-60 research reactor in the development of fast reactors

Role of the BOR-60 research reactor in the development of fast reactors

Estimating Potential Tritium and Plutonium Production in North Korea’s Experimental Light Water Reactor

Our work explores North Korea’s 100 MW-th Experimental Light Water Reactor (ELWR) and its potential contributions to the country’s nuclear weapons program. Built at the Yongbyon Nuclear Research Center, the ELWR began operations in October 2023 and represents North Korea’s first attempts at a light-water reactor using domestically-enriched fuel. Our study examines possible configurations for energy generation, tritium production, and tritium-plutonium co-production. Assuming a single-batch core, the ELWR can be used to annually produce 48–82 grams of tritium, which can supply 2–4 new boosted warheads each year, up to a maximum arsenal of 88–150 warheads total. Concurrent production of tritium and weapon-grade plutonium is also possible but requires reprocessing of spent ceramic fuel. Overall, the findings underscore how North Korea’s nuclear capabilities may be advanced through the ELWR’s dual-use potential.

Calculation of the integrated fluence and radiation damage on the MNSR reactor aluminum vessel (LT-21)

One of the major limiting factors to nuclear reactors lifetime is the radiation-induced material damage in the reactor vessel (RV). In this study, the MCNP cross-sectional library (ENDF/B-VI) was modified to evaluate and analyze the radiation damage on the aluminum vessel of the MNSR research reactor. The neutron fluence, displacements per atom (DPA), gas production rate (He and H), heating rate and silicon production were calculated in the aluminum vessel. The result showed after 5000 h of operating time, the maximum integrated fluences on the vessel surface were 4.79 × 1017 and 5.83 × 1016 n.cm−2 in the thermal and fast regions, respectively. The total damage, gas production (H and He), heating rate and silicon production were 3.14 × 10−04 dpa, 8.46 × 10−04 appm and 1.20 × 10−04 appm, 1.20 × 10−04 J/g and 1.20 × 10−04 g−1, respectively. The contribution of the fast neutrons in the radiation damage, gas production (H and He) and heating rate was most effective. The radiation damage on the reactor vessel is less than the limits, and the reactor operation can be continued.

A potential hydrogen isotope storage material Zr2Fe: deep exploration on phase transition behaviors and disproportionation mechanism

Tritium, a radioactive isotope of hydrogen, is exceptionally rare and valuable. The safe storage, controlled release and efficient capture of tritium are subject to focused research in the International Thermonuclear Experimental Reactor. However, the application of an efficient tritium-getter material remains a critical challenge. Zr2Fe alloys exhibit a strong ability to absorb low-concentration hydrogen isotopes, but their practicability suffers from disproportionation reaction. Yet, the essential de-/hydrogenation performances and disproportionation mechanism of Zr2Fe are inconclusive. Here, we designed a comprehensive series of measurements that demonstrate the ultra-low hydrogenation equilibrium pressure (2.68 × 10-8 Pa at 25 °C) and unique hydrogen-interacted phase transitions in Zr2Fe-H systems. Further kinetic and thermodynamic analyses reveal the causative reasons for disproportionation and determine the triggering temperature of the disproportionation reaction to be 375 °C in static hydrogen environments. Utilizing inversion of the Van't Hoff equation, higher-temperature hydrogen absorption models of Zr2Fe are developed, supporting a solution to the inaccuracy and inseparability of the general de-/hydrogenation and disproportionation, thereby verifying the unique disproportionation route (Zr2Fe/Zr2FeHx + H2 → ZrFe2 + ZrH2). Combined with the density functional theory (DFT) calculations, the de-/hydrogenation and disproportionation mechanisms and their interrelation can be explained in depth. This work supports the exploration and modification of the Zr2Fe-H and other metal hydride storage systems in future studies.

Performance of Gadolinium-Neutron Shielding Layer Formed by Plasma Thermal Spray Method

Plasma thermal spray coating method was applied to prepare a high performance neutron shielding layer for various applications such as nuclear spent fuel transportation and storage containers and experimental research reactors. In this study, layers with various compositions of a gadolinium oxide neutron absorber and a nickel alloy binder on a 304 stainless steels substrate were deposited by the plasma thermal spraying method, and their performance including the neutron shielding ability and the corrosion behavior was evaluated to develop a high performance thermal neutron shield coating layer. In the neutron shielding test results, layers with more than a 450 m thick coating with a 1:3 ratio of gadolinium oxide and nickel alloy binder provided 100% thermal neutron shielding against a neutron beam with energy of 48.4 meV and a wavelength of 0.13 nm. Electrochemical corrosion tests showed that the corrosion potential and corrosion rate of the thermal spray coated layers in the artificial sea water were lower than -0.833 VSHE and slower than 7.12×10-5A/cm2, respectively. Both the neutron shielding and the corrosion resistance tests results suggest that neutron shielding layers with thickness exceeding 450 m formed by the plasma thermal spraying method can be effectively applied as a thermal neutron shielding material for spent fuel transportation and storage containers and experimental nuclear reactors.

Residence time distribution experiments in a hybrid anaerobic blanket reactor treating real pharmaceutical wastewater

BackgroundThe phenomena of mixing is considered important due to its involvement in modelling and design of reactors. MethodsThe residence time distribution (RTD) experiments to find out the mixing characteristics were conducted in hybrid anaerobic blanket reactor (HABR) with four different OLRs of pharmaceutical wastewater using lithium chloride as tracer by means of stimulus-response technique. The mean hydraulic retention time, dispersion and Peclet number for various OLRs in HABR were determined. Significant findingsThe experimental COD removal efficiencies in HABR and the theoretical performance were found out using the axial dispersion flow model (ADFM) and plug flow model (PFM). The estimated theoretical chemical oxygen demand (COD) removal efficiencies, using the ADFM were 92.4%, 82.0%, 63.0% and 41.7% and the values respectively for PFM were 97.27%, 93.92%, 83.47% and 59.34%. The error percentage detected was less than 7% in ADFM which exhibited better flow representation in HABR. Furthermore, the value of correlation coefficient (R2 = 0.9956) between the theoretical COD removal efficiencies and experimental values confirmed the suitability of the ADF model.

Monte Carlo N-Particle (MCNP) simulation of neutron flux at a vertical port in the Suranaree University of Technology Research Reactor (SUT-RR) building

Monte Carlo N-Particle (MCNP) simulation of neutron flux at a vertical port in the Suranaree University of Technology Research Reactor (SUT-RR) building

Investigation of Lane-consistent dispersive optical-model potential for <sup>208</sup>Pb

Lead is an important alloy material nuclide. And lead eutectic is also an important coolant, which is applied in the construction of Lead-cooled Fast Reactor such as The European Lead-cooled System (ELSY) and the China Lead-based Research reactor (CLEAR-I), as well as in research related to Generation-IV reactor. The study and calculation of lead nuclear data have important theoretical value and application prospects. <sup>208</sup>Pb is the most stable and abundant isotope in lead nuclei, and high quality description of <sup>208</sup>Pb nuclear scattering data is the key to achieving theoretical calculations of nuclear reaction data for lead nuclei. Based on the dispersive optical model, this work describes nucleon scattering on <sup>208</sup>Pb by using the dispersive optical potential. The dispersive optical model potential is defined by energy-dependent real potentials, imaginary potentials, the corresponding dispersive contributions to the real potential which are calculated analytically from the corresponding imaginary potentials by using a dispersion relation, and isospin dependence is reasonably considered by introducing isovector component (i.e. Lane term) in the potential depth constants of the real Hartree-Fock potential <i>V</i><sub>HF</sub> and the surface imaginary potential <i>W</i><sub>s</sub>. Unlike K-D potential, which requires two different sets of parameters to describe neutron and proton induced scattering data, this optical potential uses the same set of parameters to simultaneously describe nucleon-nucleus scattering data. The derived potential in this work shows a very good description of nucleon-nucleus scattering data on <sup>208</sup>Pb up to 200 MeV. Calculated neutron total cross sections, neutron and proton elastic scattering angular distributions, as well as neutron and proton elastic analyzing powers are shown to be in good agreement with experimental data. Additionally, the difference in potential between the neutron and protons induced is described by the isovector term, a reasonable good prediction of quasielastic (p, n) scattering data is achieved.

Effect of energetic ions on edge-localized modes in tokamak plasmas

The most efficient and promising operational regime for the International Thermonuclear Experimental Reactor tokamak is the high-confinement mode. In this regime, however, periodic relaxations of the plasma edge can occur. These edge-localized modes pose a threat to the integrity of the fusion device. Here we reveal the strong impact of energetic ions on the spatio-temporal structure of edge-localized modes in tokamaks using nonlinear hybrid kinetic–magnetohydrodynamic simulations. A resonant interaction between the fast ions at the plasma edge and the electromagnetic perturbations from the edge-localized mode leads to an energy and momentum exchange. Energetic ions modify, for example, the amplitude, frequency spectrum and crash timing of edge-localized modes. The simulations reproduce some observations that feature abrupt and large edge-localized mode crashes. The results indicate that, in the International Thermonuclear Experimental Reactor, a strong interaction between the fusion-born alpha particles and ions from neutral beam injection, a main heating and fast particle source, is expected with predicted edge-localized mode perturbations. This work advances the understanding of the physics underlying edge-localized mode crashes in the presence of energetic particles and highlights the importance of including energetic ion kinetic effects in the optimization of edge-localized mode control techniques and regimes that are free of such modes.

Behavior and fate of ITER-like tungsten nanoparticles in freshwater ecosystems produced during operation and maintenance.

Within the ITER project (International Thermonuclear Experimental Reactor) an international project building a magnetic confinement device to achieve fusion as a sustainable energy source, tungsten (W) is planned to serve as a plasma-facing component (PFC) in the tokamak, a magnetic confinement device used to produce controlled thermonuclear fusion power. Post plasma-W interactions, submicron tungsten particles can be released. This study investigated the exposure of lentic freshwater ecosystems to ITER-like tungsten nanoparticles in indoor aquatic mesocosms. Monitoring included tungsten (bio)distribution, (bio)transformation, speciation, and impacts following a relevant exposure scenario (chronic, medium-term, low-dose contamination). Additionally, mechanistic studies using a combination of microfluidic cells and X-ray Absorption Spectroscopy (XAS) provided a time-resolved understanding of tungsten's oxidative dissolution in freshwater. Following contamination, tungsten persisted in the water column (over 90 %), showing significant (∼40 %) and rapid (< 7 days) oxidation-dissolution and polymerization. This led to significant exposure of planktonic niches, strong affinity of polymeric tungsten species for aquatic vegetation, and potential transfer to higher trophic levels like aquatic snails. Over five weeks, the bio-physicochemical parameters of the mesocosms remained stable, and no acute impacts were observed on micro- and macro-organisms.

Unveiling the dynamic CO2 capture performance of MgO promoted with molten salts and CaCO3via fixed bed reactor experiments

MgO promoted with molten alkali salts and CaCO3 displayed efficient CO2 capture activity in a fixed bed reactor, attaining 75% CO2 removal at 275 °C and stable cyclic performance, with the promoters providing an alternative carbonation mechanism.

Concomitant formation of protocells and prebiotic compounds under a plausible early Earth atmosphere

Revealing the origin of life and unambiguously detecting fossil remains of the earliest organisms are closely related aspects of the same scientific research. The synthesis of prebiotic molecular building blocks of life and the first compartmentalization into protocells have been considered two events apart in time, space, or both. We conducted lightning experiments in borosilicate reactors filled with a mixture of gases mimicking plausible geochemical conditions of early Earth. In addition to the variety of prebiotic organic molecules synthesized in these experiments, we investigated the micrometer-thick silica-induced organic film that covers the walls of the reactors and floats at the water-gas interface. We found that the film is formed by aggregation of HCN-polymer nanoclusters whenever water is present, either in the liquid or vapor phase. The organic film morphs into micrometer-scale biomorphic vesicular structures hanging from the organic film into the water. We also show that these structures are hollow and may act as microreactors facilitating chemical pathways toward increasing complexity. We propose that these organic biomorphs form through a bubble-driven mechanism and interfacial precipitation of HCN-polymers. The concomitant synthesis of biomorphic poly-HCN protocells and prebiotic molecules under plausible geochemical conditions of early Earth-like planets and moons and opens a different geochemical scenario for the emergence of life. Our results suggest that the coexistence of molecular building blocks of life and submicron biomorphic structures in the oldest rocks on Earth or any other celestial body does not necessarily mean evidence of life.

METHODOLOGY OF SELECTING CEMENT MATRIX COMPOSITION FOR IMMOBILIZATION OF IRRADIATED URANIUM-GRAPHITE FUEL

The Impulse Graphite Reactor (IGR) is a unique nuclear facility in the world. The core of the research reactor is a stack of uranium-graphite blocks (fuel elements) enriched to 90 wt. % in 235U isotope. As part of the project on conversion of the IGR reactor to low-enriched uranium fuel, the specialists of the Institute of Atomic Energy (IAE) studied the possibility of immobilizing the first core in a cement matrix. Research into the immobilization process included both the formation of technical requirements for the uranium-graphite fuel matrix, determined by the conversion conditions, international and national standards, and the selection of the composition and ratios of the matrix components.The paper presents the results of an analysis of modern achievements in the field of immobilization of radioactive waste and irradiated graphite, the formation of matrix acceptability criteria for the immobilization of highly enriched IGR fuel, and methods for determining whether the matrix properties correspond to the established criteria. The matrix compositions for immobilization of the irradiated fuel of the IGR reactor were selected experimentally, based on such characteristics of the cement slurry as bleed water, viscosity, setting time, uniformity of volume change, homogeneity and strength of the samples. To determine the above characteristics, the methods used to determine the characteristics of cement slurries were used and improved. They have proven their suitability.The requirements used to select the composition of matrices for immobilization of spent uranium-graphite fuel of the IGR reactor turned out to be applicable and sufficiently constructive, and can also be recommended for solving issues of selecting the consistency of matrices for immobilization of other types of RW.

Microscale Extraction of Carrier Free Re Radioisotope (188Re) from Irradiated Natural Tungsten Target for Radiopharmaceutical Preparation

ABSTRACT Among radionuclides used for targeted radionuclide therapy in nuclear medicine, rhenium-188 radioisotope is of particular relevance. No-carrier-added (NCA) 188Re was produced at the Egyptian Second Research Reactor (ETRR-2) by neutron irradiation of natural tungsten target via indirect nuclear reaction. The radiochemical separation of 188Re from irradiated tungsten target was investigated based on solvent extraction technique using Aliquat 336. Several separation parameters were checked and optimized. The batch experimental results indicated that an extraction % of 95% was obtained at pH 4, 0.1 M of Aliquat 336, and 1.5 h extraction time for extraction of 188Re, while for 187W it was around 19% at these conditions. Finally, 188Re was purified from the irradiated tungsten target by the utilization of 1 M HNO3 as a stripping agent. The stripped fractions of 188Re were of high chemical, radiochemical, and radionuclidic purity.