Research Reactor Research Articles

Neutrino charge radius and additional one-loop radiative corrections at ultranear reactor experiments

We scrutinize the potential of upcoming ultranear reactor neutrino experiments to detect radiative corrections in the elastic neutrino-electron scattering channel, focusing on the JUNO-TAO and CLOUD detectors, which employ advanced scintillator detection technologies. Previous reactor experiments have already constrained the electron neutrino charge radius, which is a neutrino property associated with a certain subset of the total radiative corrections, and have achieved limits that are only about an order of magnitude away from the Standard Model prediction. Our study demonstrates that JUNO-TAO and CLOUD could discover the neutrino charge radius in the near future, considering the established treatment of the charge radius. However, we show that it is necessary to go beyond this standard treatment. By including the complete set of one-loop level radiative corrections, we find a partial cancellation with the charge radius effect, reducing the experimental sensitivity to this quantity. Nevertheless, JUNO-TAO and CLOUD still have the potential to achieve a 5σ discovery but over longer timescales within a reasonable operational time frame. Published by the American Physical Society 2024

Evaluation of Reactor Laboratory Internet Services of Kartini Reactor Based on Regulation of the Minister of PANRB Number 14 of 2017

Kartini Reactor is one of Indonesia's research reactors that is used to learn nuclear technology. One of its services is the Internet Reactor Laboratory (IRL) with online Synchronous Learning-based implementation. To fulfill laws and regulations related to public services, meet the targets of BRIN agency work units, and evaluate to achieve excellent service, a survey is needed to assess the quality of IRL services in a Community Satisfaction Index (IKM) and Community Satisfaction Survey (SKM) using the guidelines of the Minister of PANRB Regulation Number 14 of 2017. The data collection method uses an e-questionnaire distributed to service users, which is then analyzed quantitatively. At the same time, the follow-up improvements use qualitative methods with interviews and observations. The survey results are used to evaluate and improve services to provide excellent service and fulfill community expectations and demands. The results of the quantitative analysis obtained that the results of the service IKM were 3.50 (maximum scale 4.00), and the service SKM value was 87.48 (maximum scale 100), which is included in the category of service quality B, which indicates the performance of the service unit is Good. As a further evaluation for service improvement, three service element values with the lowest values were taken: the system, mechanism, and procedure elements, service time elements, and service product specification elements. The practicum module will be classified based on the difficulty level of the system, mechanism, and procedure. In the service time element, the instructor will start and end the practicum on time, the Zoom admin will act as a time monitor, and students are directed to be present 5 minutes before the practicum. In the service specification product element, untidy practicum modules and unclear PowerPoint visualizations will be improved through synchronization of semester learning plans (RPS) with universities, adjustment of modules according to learning outcomes, standardization of visualization, and instructor training. Keywords: Internet Reactor Laboratory (IRL), Community Satisfaction Index (CSI), Community Satisfaction Survey (CSS), evaluation of practicum services

Study of spectral features and depth distributions of boron layers on tungsten substrates by ps-LIBS in a vacuum environment

Boronization is used in present-devices as wall condition technique due to its effectiveness in reducing oxygen and other impurities in the vessel as well as improving plasma performance. The technique is also currently under consideration as wall conditioning method for the proposed full-tungsten (W) wall of the International Thermonuclear Experimental Reactor (ITER). However, the impact of the deposited Boron (B) layer thickness, and its homogeneity after the boronization process is uncertain as well as knowledge about the layer lifetime and improved conditions. In this study, an approach of the picosecond-laser-induced breakdown spectroscopy (ps-LIBS) is investigated to analyze the depth distribution of B-films on W-substrates by using three optical spectrometers in a vacuum environment. The depth distribution of two types of B-films on W-substrates with the thicknesses of 130 nm and 260 nm were sequentially measured under different laser spot sizes (varying the laser fluence). The B-films on the W-substrates were made by magnetron sputtering to simulate the thin B layers during the boronization. The measured average ablation rate of ps-LIBS shows a notable decrease with increasing laser spot size. Additionally, the spectral lines of B and W exhibit distinct intensity distributions under different spot sizes due to the different excitation thresholds of the B-films and the W-substrates. The interface between B-films and W-substrates, as well as the thickness of the B-films, were determined using the normalized intensity and intensity ratio method, respectively. The results from ps-LIBS measurements regarding the depth are in good agreement with those obtained through the Focused Ion Beam combined with Scanning Electron Microscopy (FIB-SEM) and Energy Dispersive X-ray Spectroscopy (EDS). These initial findings verify the feasibility to characterize the thickness and uniformity of thin B films in the order of 100 nm and below on W-substrates using ps-LIBS.

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.

Purification of U from U-10Mo scrap generated during the fabrication of high performance research reactor fuel

ABSTRACT A low enriched U-Mo alloy fuel is under development to replace highly enriched U fuels currently used in United States high performance research reactors. The alloy casting and fuel fabrication processes will generate scrap streams containing low enriched U (LEU) which must be recovered. Solvent extraction processes were designed using the Argonne Model for Universal Solvent Extraction (AMUSE) to purify solutions containing 20 and 50 g/L U. The feed for the solvent extraction processes was prepared from solutions generated from the dissolution of U-10Mo-Zr foils and U-10Mo-Zr-Al mini-plates. The U purification processes were demonstrated using two, 16-stage banks of miniature mixer-settlers. The solvent extraction experiments demonstrated that all design objectives for the U purification processes could be met. The U recovery in the product stream for each flowsheet was ≥99.9%. The flowsheet demonstrations also showed that the purity of the U Product will meet the requirements of the ASTM International C1462-21 specification for LEU metal enriched to less than 20% 235U. The AMUSE modeling for both flowsheet demonstrations was validated by comparing predicted and measured concentrations of U, Mo, and Zr in the exit streams and stage samples at steady-state conditions in the mixer-settlers.

ITER and TRT—Technological Platforms for Controlled Thermonuclear Fusion

To solve the main problems of designing a thermonuclear tokamak reactor, such as the experimental demonstration of quasi-stationary thermonuclear burning, generation of non-inductive quasi-stationary current; development of plasma technologies and materials of the first wall and divertor, the International Thermonuclear Experimental Reactor ITER is being designed, projects of DEMO demonstration reactors are being developed, and a Tokamak with Reactor Technologies TRT is being developed in Russia. The main components of the ITER (superconducting electromagnetic system (EMS) made of Nb3Sn and NbTi, the first wall of W coated with a low-Z material, systems for additional plasma heating, experimental modules of a breeder blanket, plasma control systems, etc.) and TRT (EMS of high-temperature superconductors, first wall options of W with B4C coating, TiB2–AlN composite and liquid metal lithium, additional heating and quasi-stationary non-inductive current drive systems, innovative divertor, experimental breeder and hybrid blanket modules, reactor-compatible diagnostics and remote plasma control systems, etc.) technology platforms are presented. The technological platforms of the ITER being under construction and the TRT being designed contain an almost complete, according to modern understanding, set of technologies for the future thermonuclear reactor.

Co-pyrolysis behaviors, kinetics, and thermodynamics of sludge, lignite and biomass through fixed-bed reactor experiments and thermogravimetric analysis

Co-pyrolysis behaviors, kinetics, and thermodynamic parameters of petrochemical sludge (PS), lignite (HL), and pine wood (PW) were investigated via fixed-bed reactor experiments and thermogravimetric analysis. Fixed-bed experiments showed H2 and CO2 were main gases from PS, HL, and blends, CO from PW and PS, and CO and CH4 from PS and HL. Thermal analysis indicated that ternary blends’ de-volatilization had two parts dominated by PW and HL, respectively. The comprehensive de-volatilization index increased from 7.0 × 10-7 to 3.3 × 10-6 %2/(min2·°C3) as PW ratio rose from 20 % to 40 %. Effects of heating rates on pyrolysis properties, kinetics, and thermodynamics were studied using thermal analysis data. Characteristic indices increased, and activation energies decreased with HL or PW mixing; minimum activation energy was 147.2 kJ/mol for PS and HL blend. Blending lignite and biomass improved pyrolysis indices of petrochemical sludge and reduced activation energy and thermodynamic parameters, benefiting sludge disposal.

Efficient Tuning of an Isotope Separation Online System Through Safe Bayesian Optimization with Simulation-Informed Gaussian Process for the Constraints

Optimizing process outcomes by tuning parameters through an automated system is common in industry. Ideally, this optimization is performed as efficiently as possible, using the minimum number of steps to achieve an optimal configuration. However, care must often be taken to ensure that, in pursuing the optimal solution, the process does not enter an “unsafe” state (for the process itself or its surroundings). Safe Bayesian optimization is a viable method in such contexts, as it guarantees constraint fulfillment during the optimization process, ensuring the system remains safe. This method assumes the constraints are real-valued and continuous functions. However, in some cases, the constraints are binary (true/false) or classification-based (safe/unsafe), limiting the direct application of safe Bayesian optimization. Therefore, a slight modification of safe Bayesian optimization allows for applying the method using a probabilistic classifier for learning classification constraints. However, violation of constraints may occur during the optimization process, as the theoretical guarantees of safe Bayesian optimization do not apply to discontinuous functions. This paper addresses this limitation by introducing an enhanced version of safe Bayesian optimization incorporating a simulation-informed Gaussian process (GP) for handling classification constraints. The simulation-informed GP transforms the classification constraint into a piece-wise function, enabling the application of safe Bayesian optimization. We applied this approach to optimize the parameters of a computational model for the isotope separator online (ISOL) at the MYRRHA facility (Multipurpose Hybrid Research Reactor for High-Tech Applications). The results revealed a significant reduction in constraint violations—approximately 80%—compared to safe Bayesian optimization methods that directly learn the classification constraints using Laplace approximation and expectation propagation. The sensitivity to the accuracy of the simulation model was analyzed to determine the extent to which it is advantageous to use the proposed method. These findings suggest that incorporating available information into the optimization process is valuable for reducing the number of unsafe outcomes in constrained optimization scenarios.

Reactivity Impact of Updated 35Cl Nuclear Data on the Molten Chloride Reactor Experiment

The Molten Chloride Reactor Experiment (MCRE) will be built and operated as part of an Advanced Reactor Demonstration Project Risk Reduction Award. This fast spectrum, chloride salt–fueled molten salt reactor is sensitive to chlorine nuclear data. Recent experimental measurements of the 35Cl (n,p) cross section disagree with 35Cl nuclear data evaluations outside the bounds of the nuclear data uncertainty covariance matrices. To address this challenge, Los Alamos National Laboratory has been charged with measuring the 35Cl (n,p) cross section at the Los Alamos Neutron Science Center and generating an updated 35Cl nuclear data evaluation integrating recent cross-section measurements. This paper evaluates the reactivity impact of using the updated 35Cl evaluation on the MCRE application compared to publicly available evaluations (ENDF/B up to VIII.0 and JENDL-5).

Substantiation of the Possibility to Obtain 177Lu on the Average Flux Research Reactor IRT-T

Substantiation of the Possibility to Obtain 177Lu on the Average Flux Research Reactor IRT-T

Initial Studies of Tellurium Embrittlement in 316H Stainless Steel

Post-irradiation examination of the Molten Salt Reactor Experiment from the 1970s revealed intergranular cracking of the salt-facing material, Hastelloy-N, from the penetration of fission products, specifically tellurium (Te), into the components. Stainless steel 316H is a candidate salt-facing structural material for future molten salt reactors due to its excellent corrosion, oxidation, and neutron irradiation resistance. Thus, studies are needed to verify if Te may lead to material degradation of salt-facing components made from 316H. This work examined the behavior of stainless steel 316H in three conditions: as received, heat treated to 800°C for 100 h without Te, and with a highly concentrated Te environment. After exposure, mechanical testing was performed on all samples to reveal the loss of strength and ductility in the Te-exposed samples. Additional analysis of the Te-exposed 316H samples using scanning electron microscopy displayed intergranular embrittlement and energy-dispersive X-ray spectroscopy maps highlighted the infiltration of Te within grain boundary cracks. These results present the need for additional experiments to understand how Te weakens the structural material, especially in molten salt, and to eventually identify the driving mechanism for this observed behavior.

Determination of Minor and Trace Elements in Breast Milk of Lactating Mothers in Early Lactation from Tehran, Iran Using Neutron Activation Analysis Method.

This study aimed to evaluate the concentrations of both essential and non-essential elements in the breast milk of lactating mothers from Tehran, Iran, during the colostrum period. Neutron activation analysis (NAA) was used to measure the element concentrations. Additionally, the study assessed how these element concentrations were influenced by maternal factors such as age and economic status. Breast milk samples were collected from 95 lactating mothers, aged 18 to 41, during the early lactation phase, specifically within the colostrum period (2-7 days postpartum). The colostrum milk samples were freeze-dried, powdered, and irradiated at the Tehran Research Reactor for neutron activation analysis (NAA). This method was used to measure the concentrations of essential elements-calcium (Ca), potassium (K), sodium (Na), chlorine (Cl), and iodine (I)-as well as non-essential elements-aluminum (Al), bromine (Br), and rubidium (Rb). Descriptive statistics, including mean, median, maximum, minimum, and standard deviation, were calculated for each element. Statistical analyses, such as Pearson's correlation, were performed to assess relationships between the concentrations of various elements. Additionally, t-tests and p-values were employed to evaluate differences in element levels across maternal age groups (17-34 years vs. 35-45 years) and economic status (high/middle vs. low). The mean concentrations of the elements in dry breast milk powder samples were: Al = 6.9mg/kg, Br = 11.9mg/kg, Ca = 2.757mg/g, Cl = 7.836mg/g, I = 1.22mg/kg, K = 5.853mg/g, Na = 4.932mg/g, and Rb = 3.69mg/kg. Significant correlations were found between element pairs, such as Na-Cl, Br-Cl, Na-Br, Rb-K, and I-Cl. Maternal age significantly influenced bromine concentrations, with older mothers showing 22% higher Br levels (p = 0.038), while calcium levels were 15% lower but not statistically significant (p = 0.20). Maternal economic status significantly impacted calcium and potassium concentrations, with higher levels observed in mothers from better economic conditions (p = 0.02 and p = 0.025, respectively). This study highlights the elemental composition of breast milk samples of lactating mothers in Tehran and shows that maternal factors, such as age and economic status, can significantly influence the concentrations of specific elements in breast milk.

Addendum to: Combined analysis of neutrino decoherence at reactor experiments

Addendum to: Combined analysis of neutrino decoherence at reactor experiments

Elucidating high-pressure chemistry in acetylene oxidation: Jet-stirred reactor experiments, pressure effects, and kinetic interpretation

Acetylene plays a crucial role as an intermediate in the combustion of complex hydrocarbons, such as, e.g., jet fuels. In this study, high-pressure acetylene oxidation has been investigated by a combination of kinetic and experimental methods using a jet-stirred reactor (JSR) in the range of 497–910 K at p = 24 atm. The study covered three fuel-equivalence ratios: φ = 0.5 (fuel-lean), φ = 1.0 (stoichiometric), and φ = 3.0 (fuel-rich). Mole fraction profiles of 10 species, including CO, CO2, CH4, C2H4, C2H6, C3H6, C3H8, CH3OH, CH3CHO, and C3H4O, were identified and quantified using gas chromatography (GC) and gas chromatography-mass spectrometry (GC–MS). A kinetic model for describing the high-pressure chemistry of acetylene oxidation is proposed, which well characterizes important experimental findings, such as the fuel oxidation reactivity and the speciation of crucial products. At high pressures (p = 24 atm), acetylene exhibits a higher fuel consumption than at lower pressures (p = 1 and 12 atm) because of the increased sensitivity of dehydrogenation reactions by OH radicals accelerating the oxidation of the fuel at low temperatures. Furthermore, fuel-specific intermediates are observed, including acetaldehyde, propanal, small alkanes, and alkenes. These species mainly result from H-abstraction reactions by OH following O2-addition reactions from triple carbon bond moieties in acetylene. The formation of further products, such as carbon monoxide and carbon dioxide, is closely related to the consumption of these fuel-specific species. In particular, the formation of aromatics, such as e.g., benzene and toluene, are detected at trace levels in the current experiments due to the rapid formation and decomposition process occurring at high pressures. By analyzing the distinct kinetic behavior, it was found that acetylene was almost completely depleted at higher system pressure (p = 24 atm). Some intermediates are rather active and can react with O2 and peroxides. Consequently, the high-pressure oxidation of acetylene mainly proceeds along the pathway of CC → CHCHOH → HOCHO/OCHCHO → CO → CO2 at the high-pressure chemistry (p = 24 atm). Overall, this study provides valuable insights into the pressure-dependent combustion behavior of acetylene and its implications for optimizing jet fuel combustion processes.

Monte Carlo simulation of photo-peak efficiency response function and calculation of total efficiency for a NaI (Tl) scintillator detector

Abstract NaI (Tl) scintillation detectors are widely used in laboratories and in the field of gamma-ray spectrometry where detector efficiency is a key factor for successful quantitative γ ray analysis. In this work, Monte Carlo simulations using MCNPX code have been performed in order to evaluate energy resolution as a full width at half maximum (FWHM) of the peak and absolute efficiency of NaI detectors. Also, the detection efficiency and energy resolution for the NaI (Tl) scintillation detector of Tehran Research Reactor (TRR) pollution monitoring laboratory was measured. Simulation results were compared to experimental data and good agreement are obtained. In radioactive analyzing laboratory, precise determination of the detector efficiency according to any different gamma energy is a very important parameter whereas it uses in daily laboratory work.

Optimizing food waste anaerobic digestion in Kuwait: Experimental insights and empirical modelling using artificial neural networks.

This study investigates, for the first time, the anaerobic digestion of food waste in Kuwait to optimize methane production through a combination of artificial neural network (ANN) modelling and continuous reactor experiments. The ANN model, utilizing eight hidden neurons and a 70-20-10 split for training, validation and testing sets, yielded mean squared error values of 0.0056, 0.0048 and 0.0059 and coefficient of determination (R²) values of 0.9942, 0.9986 and 0.9892, respectively. Methane percentages in biogas were predicted using six parameters: biomass type, pH, organic loading rate (OLR), hydraulic retention time (HRT), temperature and reactor volume. To validate the ANN results, continuous reactor experiments were conducted under an OLR of 3 kg VS m⁻³ d⁻¹ and HRT of 20 days at varying temperatures (35°C, 40°C, 45°C, 50°C and 55°C). The experiments demonstrated optimal methane production in the mesophilic range, with ANN predictions closely aligning with experimental data up to 45°C. However, deviations were observed at higher temperatures, particularly under thermophilic conditions beyond 50°C. This study provides novel insights into waste-to-energy initiatives in Kuwait and highlights the potential of integrating computational models with empirical data to enhance biogas production processes.

The chlorination and separation of aluminum using low-temperature sulfur chloride reagents

ABSTRACT There is currently no strategy for the permanent waste disposal or recycling for used nuclear fuels from research reactors. For this reason, low-temperature reactions have been developed for the chlorination of the Al alloys and subsequent separation from used nuclear fuels to reduce the volume of high-level waste in storage. Three sulfur chloride reagents – S2Cl2, SOCl2, and SO2Cl2—were tested, and two were found to quantitatively chlorinate Al metal and Al alloys under mild conditions. These low-temperature reactions proceed between 298 and 411 K, and up to 5 g of metal is chlorinated in 1–3 h. Preliminary results indicate that the reactivity and exothermicity of the reaction between the Al and sulfur chloride reagents is highly dependent on the surface area-to-volume ratio of the metal and the volume of solvent. Elemental S is produced as a by-product during the chlorination with S2Cl2 but can be quantitatively rechlorinated under mild conditions to regenerate the initial chlorination reagent. Therefore, in this case, chlorine is the only element consumed in the reaction, thus minimizing the waste generated during the chlorination process. The AlCl3 may then be separated from other materials present in Al 6061 or Al 8001 because of its high solubility in the sulfur chloride reagents. This process may also be extended to chlorinate Al from research reactor fuels.

Measurements of neutron capture cross-section for nuclides of interest in decommissioning (II): 58Fe(n,γ)59Fe

ABSTRACT As nuclear facilities are dismantled in decommissioning, large amounts of various waste are generated. Even more inconveniently, such waste is radioactive due to neutron activation. Thus, the neutron capture cross-sections of nuclides targeted in decommissioning are required to evaluate the radioactivity produced. In this work, 58Fe nuclide was selected among objective nuclides for decommissioning, and its thermal-neutron capture cross-section was measured by a neutron activation method at the graphite thermal column of Kyoto University Research Reactor in 5-MW operation. The thermal-neutron capture cross-section was derived using Westcott’s convention. The present work obtained 1.36 ± 0.03 barns for the58Fe(n,γ)59Fe reaction. The present result supports the JENDL-5 evaluation within 2σ. If updated with currently recommended nuclear data, some of the reported past data would support the present result.

Application of metal-ceramic uranium-molybdenum fuel in an aluminum matrix for research reactors

Application of metal-ceramic uranium-molybdenum fuel in an aluminum matrix for research reactors

Impact of High-Reactivity Advanced Test Reactor Experiments on Photon Heating in Nearby Experiment Locations

The Advanced Test Reactor’s (ATR’s) distinctive ability to provide a wide range of irradiation conditions is attractive for programs pursuing fuel qualification experiments. These potentially high-fuel-load experiments are a relatively new development and produce unexplored effects on nearby experiments. This paper explores how photon heating of such an experiment may affect other nearby experiment programs, ultimately serving to better inform decisions regarding experiment design and risks to programmatic goals. The MC21 (Monte Carlo for the 21st Century) code is used to model and study how gamma heat generation rates and axial effects impact different ATR positions. The results reveal that the proximity of a given experiment’s position to the high-fuel-load one can significantly alter that experiment’s expected axial profile.