We have developed a homemade neutron flux detection module with 3He tube hot-swap capability and control-rich Android software interface. Real-time data analysis is done by a smartphone with Android application interfaced with the detector via a USB cable. This setup can be used as a neutron and gamma ray background detector or as a compact, mobile 3He tubes calibration tool making it a cheap and easy-to-use alternative for the stationary setups. A fast neutron detection algorithm was implemented as a set of Java scripts and tested for real-time signal analysis. The modular structure of the device allows easy deployment and customization with further software development and regular upgrades. The current prototype was tested at the Nuclear Physics Research Institute under different neutron flux intensity conditions from the VVR-K water-cooled research reactor. Its simplicity and significantly lower cost, compared with conventional detector equipment, make it valuable for easy repetitive tasks with medium requirements for precision and neutron flux intensities.

Research and development of materials in the nuclear industry, including the assessment of irradiated components in nuclear power plants, rely heavily on research infrastructures that facilitate the preparation and analysis of radioactive samples. The metallographic preparation of samples must be carried out in shielded, hermetically sealed boxes and hot cells, as a large amount of dusty radioactive particles is released during the sample preparation process. Small samples, thin films for scanning and transmission electron microscopy (SEM, TEM), and powdered samples from biological shielding concretes are prepared in glove boxes, where a constant negative pressure is maintained. The enclosures of the boxes are constructed of thick-walled steel plates to shield against the ionizing radiation emitted by radioactive samples, protecting personnel. Subsequent microscopic analyses allow for the assessment of material degradation in operational nuclear power plant components caused by radiation-induced microstructure damage. These analyses focus both on existing materials, with the aim of extending the lifespan of nuclear power plants, and on newly tested materials irradiated as part of domestic and international programs, including those conducted at research reactors like LVR-15, operated by the Řež Research Center (CVŘ). Different analytical requirements call for the preparation of various types of samples. At CVŘ, X-ray diffraction analysis of powdered samples is primarily used to evaluate structural and phase changes in the cement and aggregate of concrete structures caused by radiation aging, which can impact the overall integrity of the structure. Monitoring these changes and predicting material behavior are essential for evaluating the safety, stability and durability of concrete used in biological shielding, containment structures, spent nuclear fuel storage pools and future deep radioactive waste repositories. Thin films for electron microscopy are prepared specifically to assess detailed changes, such as radiation-induced microstructure damage in reactor internals or fuel cladding, which result in dimensional changes and the degradation of mechanical properties due to neutron radiation.

Abstract Nowadays, it is said that nuclear fusion — a potentially clean and abundant source of energy that scientists have been pursuing for decades — has reached a pivotal point. The political economy of fusion research was once centred on the International Thermonuclear Experimental Reactor (ITER), an intergovernmental project intended to demonstrate the technoscientific feasibility of fusion energy. However, leadership in the fusion landscape has recently shifted towards a new movement of private start-ups that are planning to build their own proof-f-principle reactors, offering a faster, cheaper, smaller-scale approach than ITER. But what does this change in leadership from a government-led project to market-driven start-ups mean in practice? This study examines the discourse surrounding the shift from public to private fusion development by qualitatively analysing “bridging events” in which fusion experts from ITER and start-ups publicly discuss their field of research, its prospects, and the pros and cons of handing over to the private sector. The analysis thus reveals that the two lines of research — ITER versus start-ups — are intertwined in a scientific controversy concerning the optimal size, design, cost, timeframe and innovation strategy for constructing a proof-of-principle fusion reactor. Both innovation strategies have their merits and limitations, which this study critically discusses.

The role of chlorine as a neutron poison and as a seed for producing radioactive waste in nuclear systems has driven a renewed interest to improve its nuclear data uncertainties. Additionally, basic and applied science programs that use CLYC (Cs_2LiYCl_6:Ce) detectors for neutron spectroscopy and monitoring are also very sensitive to any change in chlorine nuclear data for simulations of the detector response. In this work, sensitivities relevant for these different applications are addressed through simulations of the efficiency of CLYC detectors in a fast fission spectrum when applying new chlorine nuclear data as input. These simulations are validated by an experimental measurement using CLYC detectors coupled to an ionization chamber loaded with a ^{252}Cf spontaneous fission source. The results are then used to obtain the first reliable direct measurement of the ^{35}Cl(n,p_0) and summed ^{35}Cl(n,p+n,alpha) fission spectrum average cross sections, found to be 54.7(32) and 105.0(98) mb, respectively. The results are within uncertainty of calculated fission spectrum averaged cross sections based on recently re-evaluated chlorine nuclear data, which confirm recent impact studies performed for the Molten Chloride Reactor Experiment. Meanwhile, there currently exists only one published criticality benchmark experiment that is sufficiently sensitive to chlorine nuclear data. Discrepancies are found with this set of criticality safety benchmarks, which are more sensitive to thermal and epithermal neutron energies than the energies, above 100 keV, tested in this current work. Hence, there is still a need to re-evaluate the chlorine nuclear data at lower energies to assess these discrepancies. Interpretation of the data from future “faster” criticality benchmarks, which are needed for next-gen fast reactor designs, benefit from the improved constraints on the chlorine nuclear data validated in this work.

Research reactors: Global perspectives and insights into Saudi Arabia’s advancements and future prospects

FissionIST: A hardware-based research reactor simulator

Development of non-carrier added Au-199 production procedure from neutron-irradiated Pt targets.

Overview on the influencing factors of spent nuclear fuel disposal plan for Malaysian research reactor

Two-step extraction chromatography separation of 161Tb from 160Gd-enriched irradiated target material and verification of the [161Tb]TbCl3 suitability for radiolabelling.

Assessment of sapphire crystal performance with different crystal planes (111) and (112) in neutron and gamma filtration.

Neutrinos are the most abundant fundamental matter particles in the Universe and play a crucial part in particle physics and cosmology. Neutrino oscillation, discovered about 25 years ago, shows that the three known species mix with each other. Anomalous results from reactor and radioactive-source experiments1 suggest a possible fourth neutrino state, the sterile neutrino, which does not interact through the weak force. The Karlsruhe Tritium Neutrino (KATRIN) experiment2, primarily designed to measure the neutrino mass using tritium β-decay, also searches for sterile neutrinos suggested by these anomalies. A sterile-neutrino signal would appear as a distortion in the β-decay energy spectrum, characterized by a discontinuity in curvature (kink) related to the sterile-neutrino mass. This signature, which depends only on the shape of the spectrum rather than its absolute normalization, offers a robust, complementary approach to reactor experiments. Here we report the analysis of the energy spectrum of 36 million tritium β-decay electrons recorded in 259 measurement days within the last 40 eV below the endpoint. The results exclude a substantial part of the parameter space suggested by the gallium anomaly and challenge the Neutrino-4 claim. Together with other neutrino-disappearance experiments, KATRIN probes sterile-to-active mass splittings from a fraction of an eV2 to several hundred eV2, excluding light sterile neutrinos with mixing angles above a few per cent.

Iron oxide-mediated enhancement of extracellular electron transfer and symbiosis in consortium of electroactive bacteria and microalgae for wastewater treatment.

Compared with traditional fuel elements, annular fuel elements can reduce the maximum fuel temperature and provide a higher safety margin at the same power, improving the minimum critical heat flux ratio and fuel utilization rate. As the most promising core in the Generation IV reactors, a lead-based fast reactor, combined with annular fuel elements, can significantly optimize the core performance, improving the safety and economy of the fast reactor. Accordingly, a long-life lead-based fast reactor with annular fuel elements (LLFRAF) is designed in this paper. The reactor has the advantages of strong proliferation capacity, long life, and high economy, with a nearly 30-year refueling cycle. It can be used as a power reactor to provide electric energy and as a research reactor to conduct research on the performance of breeder reactors, providing crucial reference value for the optimization of fast neutron breeder reactors structure. This paper focuses on the design of the core about structural dimensions, layout of assemblies, etc. as well as physical calculation on analysis of the control system value, core fuel consumption, etc. The results show the LLFRAF meets the physical design criteria of the core, preliminarily verifying the feasibility and rationality of the core.

This study explores approaches to overcome mass transport limitations in organic electrosynthesis, which present significant challenges for industrial implementation. We first investigated convection-enhanced mass transport, demonstrating that the Sherwood number effectively characterizes mass transport conditions regardless of the convection mechanism. Our results showed that forced liquid convection and bubble-induced convection produce equivalent electrochemical performance when operating at the same Sherwood number, providing a unified framework for scaling and predicting reactor performance. Building on this foundation, we subsequently examined a complementary strategy: increasing bulk organic concentration beyond solubility limits to create multiphase systems. Using adiponitrile production as a model system, we developed an experimental flow reactor to systematically investigate how organic phase distribution affects reaction outcomes. Our findings reveal that strategic manipulation of the organic phase fraction dramatically improves reaction selectivity, with Faradaic efficiency towards adiponitrile increasing from less than 50% to over 80% at high current densities when acrylonitrile fraction surpasses the solubility limit. However, higher organic concentrations also shift the product distribution, creating a critical balance between desired product selectivity and competing side reactions. We seek to identify optimal operating regimes with respect to hydrodynamics (interelectrode spacing, flow rate, organic loading) that affect critical performance metrics including selectivity, production rate, and energy efficiency. These sequential investigations provide complementary approaches to addressing mass transport challenges in organic electrosynthesis, offering a comprehensive framework for optimizing electrochemical systems for sustainable chemical manufacturing.

ABSTRACT Decommissioning a nuclear facility generates a large amount of waste of several types, and to make things even more complicated, it is radioactive due to neutron activation. Thus, neutron capture cross-sections are required to assess the generated radioactivity of nuclides targeted for decommissioning. This study selected 95Zr and 97Zr nuclides among the nuclides targeted for decommissioning and aimed to measure the thermal-neutron capture cross-sections of 94Zr and 96Zr, which contribute to the production of 95Zr and 97Zr, respectively. Considering the relatively small cross-sections of Zr isotopes, measurements were performed by a neutron activation method using the pneumatic tube PN-3 of the Japan Research Reactor-3 (JRR-3) because its thermal-neutron flux is 250 times larger than that of the graphite thermal column of the Kyoto University Research Reactor. A high-purity natural Zr foil was irradiated at the PN-3 and subjected to γ-ray spectroscopy measurements. The thermal-neutron capture cross-sections were derived according to Westcott’s convention to be 50.9 ± 0.6 millibarns for the 94Zr(n,γ)95Zr reaction, and 21.9 ± 0.3 millibarns for the 96Zr(n,γ)97Zr reaction. These results agree with recent evaluation and experimental data. It was also demonstrated that the thermal-neutron capture cross-section of the order of millibarns is able to be measured by using the JRR-3.

Radioisotopes 152Eu and 154Eu are suitable options for calibrating HPGe detectors due to their long half-lives, high spectral purity, and distinct gamma lines. In this study, the production of these radioisotopes through direct irradiation of natural europium in the Tehran Research Reactor was investigated. For the optimal design of the irradiation process, the MCNPX 2.6.0 simulation code was used and then the practical production of the radioactive source was carried out under specified conditions. The sample was irradiated at a location with a neutron flux of 1.31 n/(cm²s) for 2 days, and after a 21-day cooling period, gamma spectroscopy was performed using an HPGe detector. The experimental results showed that the obtained activities were in good agreement with the simulation predictions. Additionally, a comparison of the detector efficiency using the produced source and a standard reference source confirmed the proper performance of the produced source. This study shows that the combination of simulation and experimental methods can provide an efficient and reliable approach for producing radioactive standard sources in research reactor environments. It can also be concluded that, given the natural abundance and lower cost of natural europium compared to the enriched isotopes 151Eu and 153Eu, its use as the primary target is a cost-effective and practical solution for the production of standard calibration sources.

Solar-assisted pyrolysis is a sustainable process for the conversion of biomass into bio-oil using renewable solar-thermal energy with potentially zero carbon footprint. The EU’s target of reducing net greenhouse gas emissions to at least 55% by 2030 leads the way to effective measures in limiting carbon emissions for a climate-neutral future. This study focuses on the initial design and development of a drop-tube fast pyrolysis reactor that performs the conversion of waste biomasses into bio-oil at 600°C, by using concentrated solar power. This work is part of the European Union-funded project, Circular Fuels, which focuses on the production of sustainable aviation fuels (SAFs). The numerical CFD simulations were performed using the ANSYS FLUENT 2020 commercial CFD solver for the sizing and design optimization of the experimental solar reactor prototype.

Abstract. Bicyclic peroxy radicals (BPRs) from aromatics hydrocarbons oxidation play increasingly recognized roles in the formation of secondary air pollutants. However, their reaction mechanisms remain poorly constrained, largely due to the lack of direct measurement techniques. In this study, we developed a method for quantitative measurement of BPRs using an iodide chemical ionization mass spectrometer (Vocus AIM). Following instrument optimization, the sensitivity for BPRs reached 0.3–0.6 ncps pptv−1, with a detection limit of ∼ 1 pptv and an uncertainty of ∼ 41 %. Our flow reactor experiments revealed that the bicyclic pathway dominates the OH-initiated oxidation of aromatics under low-NOx conditions, accounting for 57.0 % and 69.5 % of the oxidation products of toluene and m-xylene, respectively. Comparative analysis further demonstrated that conventional product-yield-based approaches underestimate the branching ratio of the bicyclic pathway by 4 %–9 % relative to direct BPR quantification. This discrepancy suggests the presence of unaccounted reaction channels in current chemical mechanisms, even when autoxidation and accretion reactions are considered. By directly quantifying BPRs, this study provides new insights into the atmospheric oxidation of aromatics and highlights the need for further mechanistic investigation. Moreover, the reaction-pathway-controlled quantification approach proposed here effectively reduces the challenges associated with measuring functionalized RO2 radicals and demonstrates strong potential for sensitive, speciated RO2 detection using Vocus AIM in both laboratory and ambient environments.

Assessing spent nuclear fuel (SNF) integrity is essential for ensuring radiation safety throughout its storage duration. One of the widely used methods is the sipping test, a nondestructive technique for detecting leaks in SNF by analyzing the release of radioactive material. While sipping tests have been applied to various reactor types, detailed designs and procedures for SNF from the Materials Test Reactor (MTR) remain limited. This study presents the design and operational procedure of a sipping test for MTR-type SNF from the Gerrit Augustinus Siwabessy research reactor in a wet storage facility, covering key components and procedures for the test. The test system is comprised of a custom-designed sipping tube, SNF basket, crane, and supply pipes for demineralized water and compressed air. The results demonstrate efficient system functionality, ensuring safe and smooth SNF handling, effective pool water replacement by demineralized water injection, thorough homogenization before sampling, and reliable test water sampling over multiple test intervals. The findings provide insights into the effectiveness of the sipping test for SNF integrity assessment and contribute to best practices for the management of a wet storage facility.

Since North Korea left the Treaty on the Nonproliferation of Nuclear Weapons in 2003, its nuclear fuel cycle has continued to operate and develop further, without transparency to international inspectors. A recent addition is the Experimental Light Water Reactor that started operation in October 2023. One concern is that this reactor may be used to produce plutonium for nuclear warheads, in addition to or instead of being used for electricity production. In this work, fissile material production in the new reactor is explored by modeling a possible core design and integrating information from available remote monitoring, such as satellite imagery of cooling water outlets from the facility. The results indicate that running the reactor with an initial enrichment of 1.75% or lower could potentially produce up to 20 kg of weapons-grade plutonium annually, substantially increasing North Korean plutonium production.