Modular Reactor Research Articles

A comprehensive assessment on recent advancements in spent fuel reprocessing and waste management: pioneering technologies for a sustainable nuclear future

Abstract This work analyzes advancements in nuclear energy, focusing on spent fuel reprocessing and waste disposal. Key technologies such as pyroprocessing, aqueous reprocessing, and the DUPIC (Direct Use of Spent PWR Fuel in CANDU) process are examined for their effectiveness in reducing environmental and safety risks. Pyroprocessing is highlighted for its ability to enhance actinide recovery and reduce waste volume, while the PUREX process demonstrates high recovery efficiencies for uranium and plutonium. The integration of Computational Fluid Dynamics (CFD) and chemical kinetics modeling optimizes process parameters, improving reprocessing outcomes. The DUPIC method shows potential in improving reactor performance and minimizing waste. Long-term waste management strategies, such as dry cask storage and geological disposal, are also explored, with advancements in safety and heat dissipation technologies. Innovations like autonomous passive cooling and antineutrino monitoring are promising for spent fuel management security. Additionally, the study highlights Generation IV reactors and Small Modular Reactors (SMRs) as critical to minimizing nuclear energy’s environmental impact. The work emphasizes continued progress in reprocessing and waste management to address technical, economic, and environmental challenges, ensuring the viability of nuclear energy.

Valorization of C2 + Hydrocarbons Via Plasma Processes

Abstract Hydrocarbon chains produced as byproduct of natural gas extraction and petrochemical processing can be valorised into syngas/H2 and oxygenated fuels in a modular fashion through electrified modular plasma reactors. A plethora of configurations is available for light hydrocarbons reforming, with cold plasma assemblies emerging as the favourite option for both gas-phase and biphasic gas/liquid set-ups. Accurate control of dehydrogenation or partial oxidation reactions is provided by the implementation of a catalyst or through microreactor technology. On the contrary, warm plasma reactors are more suitable for reforming of gasoline/diesel chains, promoting higher throughput of H2 per energy input. This reaction route does not necessarily require the deployment of a catalyst, hence making these systems more suitable for modular, decentralized processes. Online diagnostic techniques shed light on the reaction mechanism, where solid carbon deposits embody a low-value byproduct.

Experimental Operation of a Prototype 750C Advanced Chloride Molten Salt Bellows Valve

To achieve DOE 2030 SunShot targets that reduce the cost of liquid-based solar by an additional 40% to 70% beyond 2018 costs, a more reliable, highly manufacturable flow valve, capable of achieving operational temperatures of >700°C is required [1]. This paper investigates the development of an innovative high-temperature chloride molten salt valve, with operation up to 750°C. This valve is intended to be employed within Gen 3 CSP liquid-based thermal energy storage (TES) systems as well as Gen 4 modular salt reactor (MSR) technologies. This work details the general design and flow testing of a bellows-seal flow control valve (FCV). This design includes an integrated closed-loop thermal control system to ensure robust design for freeze-thaw cycles. The self-contained thermal management STM system, is unique in the salt valve industry since it is an integrated solution to provide a consistent, repeatable alternative to typical heat tracing. Additionally, the design includes the employment of a novel heat pipe valve stem to facilitate enhanced passive thermal management into the valve assembly. This valve stem heat pipe is designed to facilitate natural circulation within the bonnet to ensure robust operation, during both nominal and transient thermal operation. The valve body and trim will be designed using SS316H, consistent with Flowserve Corporation’s existing product base and is code qualified but will utilize clad material for materials corrosion, manufacturing cost reduction and compatibility to ensure design flexibility. A test campaign was performed in this investigation utilizing a novel 750°C ternary chloride (20%NaCl/40%MgCl2/40%KCl by mol. wt. %) molten salt flow loop. A discussion about the design and installation of the valves within this test bed is provided for this investigation. Valve test results from this study assessed Cv curves as well as multiple actuator cycles, under varying thermodynamic and operational mode conditions, which would be characteristic within a commercial molten salt facility. The results indicate nominal operation for the baseline design, though improved performance and reliability is expected with the full designed FCV.

Development and evaluation of a two-dimensional neutron diffusion model of a small modular heat-only reactor TEPLATOR using COMSOL

Development and evaluation of a two-dimensional neutron diffusion model of a small modular heat-only reactor TEPLATOR using COMSOL

Global Competitiveness Potential of U.S. Nuclear Energy Technologies

The new Trump administration considers the U.S. nuclear energy industry as one of the most important and promising tools for maintaining the country’s global leadership in the international arena. In order to assess the validity of these calculations, this paper provides a retrospective analysis of the development of U.S. nuclear industry, identifies its strengths and weaknesses and the overall state as D. Trump is about to enter his second term. The first section outlines the key stages and drivers of the U.S. nuclear energy industry evolution in the second half of the 20th century. The author notes that the development of the industry was steadily slowing down after a period of rapid growth in the 1960–1970s due to both purely economic reasons and extraordinary factors, including the accident at the Three Mile Island nuclear power plant. The second section compares the approaches of the administrations of George W. Bush, B. Obama, D. Trump and J. Biden to regulating the national nuclear energy industry. The research shows that, despite active government support of the industry, the trend towards a ‘nuclear renaissance’ emerged only with D. Trump's coming to power, as he set a course to restore the competitiveness of the country’s nuclear industry and establish dominance in this segment of international energy market. The author concludes that the U.S. nuclear energy technologies have significant potential in terms of strengthening the country’s global competitiveness, which, in particular, became possible thanks to the policy of the last two administrations to subsidize and technologically upgrade the nuclear industry, as well as to develop new markets in Europe and Asia. At the same time, as the author notes, there are still certain capacity constraints, related, in particular, to the disposal of spent nuclear fuel and the transition to cost-effective production of small modular reactors.

Steam Condensation Scaled Experiment in the Presence of Non-Condensable Gases for Small Modular Reactor Containment Passive Safety

This study presents scaled experiments using steam condensation with non-condensable gas (NCG)—helium (He), simulating hydrogen, and nitrogen (N2)—as these experiments are pivotal for water-cooled reactor passive containment cooling system (PCCS) design and analysis. Research into PCCSs for small modular reactors (SMRs) is especially important in light of SMR system design; however, studies in the literature reflect limitations due to test geometry and operational condition variations, without considering SMR prototypic design. To address these challenges, a scaled test facility was developed to accurately replicate SMR PCCSs. This facility includes vertical down-flow condensing test sections with 1-, 2-, and 4-in.-diameter condensing tubes, accompanied by annular water cooling. Experiments were conducted using both superheated and saturated steam, with steam mass flow rates in the presence of NCG varying from: (a) 55 to 66 kg/hr. of steam, and 1.8 to 22 kg/hr. of He (as the NCG); (b) 58 to 63 kg/hr. of steam, and 4.4 to 13.3 kg/hr. of N2 (as the NCG). Test data were collected on (a) the axial temperatures of the annular cooling water; (b) the outer wall temperature of the condensers; and (c) the mass flow rate, temperature, and pressure at the test section inlets and outlets. These primary test data were used in conjunction with a standard data reduction methodology to estimate essential thermal parameters such as heat fluxes, heat transfer coefficients, and condensation rates. The effects of NCGs on steam condensation within the geometry of the scaled test sections were then presented in regard to various testing conditions.

The Future of Nuclear Energy: Key Chemical Aspects of Systems for Developing Generation III+, Generation IV, and Small Modular Reactors

Nuclear power plants have the lowest life-cycle greenhouse gas emissions intensity and produce more electricity with less land use compared to any other low-carbon-emission-based energy source. There is growing global interest in Generation IV reactors and, at the same time, there is great interest in using small modular reactors. However, the development of new reactors introduces new engineering and chemical challenges critical to advancing nuclear energy safety, efficiency, and sustainability. For Generation III+ reactors, water chemistry control is essential to mitigate corrosion processes and manage radiolysis in the reactor’s primary circuit. Generation IV reactors, such as molten salt reactors (MSRs), face the challenge of handling and processing chemically aggressive coolants. Small modular reactor (SMR) technologies will have to address several drawbacks before the technology can reach technology readiness level 9 (TRL9). Issues related to the management of irradiated graphite from high-temperature reactors (HTR) must be addressed. Additionally, spent fuel processing, along with the disposal and storage of radioactive waste, should be integral to the development of new reactors. This paper presents the key chemical and engineering aspects related to the development of next-generation nuclear reactors and SMRs along with the challenges associated with them.

Transient analyses on overpower transients of small modular natural circulation Lead-cooled fast reactor SNCLFR-100

Abstract In order to investigate the transient safety characteristics, Unprotected Transient Overpower (UTOP) and Protected Transient Overpower (PTOP) of small modular natural circulation lead-cooled fast reactor SNCLFR-100 were performed using MPC_LBE, a multi-physics coupled safety analysis code for lead-based reactor. The simulation results indicated that the negative reactivity feedback effect of the reactor during transient slowed down the accident process, and the natural circulation capability of the reactor ensured the heat removal from the core after accident. Under both UTOP and PTOP transient conditions, the peak temperatures of coolant and fuel pellet in the hottest channel of the core did not exceed the safety design limits. The reactor could re-establish a new steady state through natural circulation in UTOP transient, and it was shut down safely after reactor scram triggered in PTOP transient.

Survey of Opportunities for Coal to Nuclear Conversion in Texas

This technical report aims to provide energy developers and policymakers with information and preliminary analyses on the potential for Texas coal plant sites to be repurposed for nuclear power. Investigation into coal-to-nuclear (C2N) has shown that constructing a nuclear reactor on the site of a retired coal plant has both economic and environmental benefits. The data presented includes operational details of the coal power plants, the presence of nearby hazards, geological and hydrological data, and population statistics. This information was gathered for 19 coal powered electricity generation sites in Texas. Thirteen of the sites assessed have no hazards or other factors that would disqualify them from hosting a Small Modular Reactor (SMR). Of these, 11 sites are also suitable for a Light Water Reactor (LWR). The smaller size and power output of SMRs makes these additional 2 sites possible, even near a population center. The remaining 6 coal plant sites would require more specific on-site analysis or potential adjustments to the reactor design to be considered for licensing. These findings exhibit the potential for cost effective nuclear development to benefit grid stability and provide baseload power to Texas.

Performance Analysis and Improvement of Data-Driven Fault Diagnosis Models under Domain Discrepancy base on a Small Modular Reactor

Performance Analysis and Improvement of Data-Driven Fault Diagnosis Models under Domain Discrepancy base on a Small Modular Reactor

Evaluating the economic and environmental viability of small modular reactor (SMR)-powered desalination technologies against renewable energy systems

Evaluating the economic and environmental viability of small modular reactor (SMR)-powered desalination technologies against renewable energy systems

Overview of Small Modular and Advanced Nuclear Reactors and Their Role in the Energy Transition

Overview of Small Modular and Advanced Nuclear Reactors and Their Role in the Energy Transition

Photochemical on-demand production of hydrogen peroxide in a modular flow reactor

Hydrogen peroxide (H2O2) is a green oxidant and potential energy carrier. Using iron oxide nanoparticles in a photo-flow reactor, an improved H2O2 production of >14× over batch conditions was obtained, achieving solutions of 0.02 wt% H2O2.

Steady-State Modeling of Small Modular Reactors for Multi-Timescale Power System Operations With Temporally Coupled Sub-Models

Steady-State Modeling of Small Modular Reactors for Multi-Timescale Power System Operations With Temporally Coupled Sub-Models

Genetic algorithm-based non-synchronous unit-specific optimal load-following control of multi-unit small modular reactor

Genetic algorithm-based non-synchronous unit-specific optimal load-following control of multi-unit small modular reactor

Comprehensive thermodynamic analysis and simulation of electrified modular reactors for bi-reforming of methane

Comprehensive thermodynamic analysis and simulation of electrified modular reactors for bi-reforming of methane

Carbon reduction and nuclear energy policy U-turn: the necessity for an international treaty on small modular reactors (SMR) new nuclear technology

Pressure to reduce carbon emission and meet Net-zero targets is forcing countries to re-introduce nuclear energy in their energy-mix. As a result, many countries have re-classified nuclear energy as a green energy to encourage investments and developments in this sector. Further, advances in nuclear energy technology have led to the development of Small Modular Reactors (SMR), which has continued to stimulate increasing interests from both developed and developing countries. Hence, it is expected that in the coming years, there would be increased deployment of SMR across the globe. This renewed interest in nuclear energy and expected global deployment of the novel SMR, would encounter some legal issues. Therefore, this paper analysed the nuclear energy international legal and regulatory frameworks (relevant nuclear energy conventions and treaties) currently used for the conventional large nuclear power plants (NPPs) to understand how adequate they are for SMR deployment. Various critical gaps were found in the extant laws that could make them not to fully cater for all the peculiarities of the new SMR nuclear technology. This may affect the effective regulation and smooth deployment of SMRs across countries. Therefore, this paper argues that a single specific international treaty on SMR that will cover the regulation of all aspects of SMR deployment, and their peculiarities is highly needed to support countries to justly transition into a Net-zero era.

Extraction of Scandium from Coal Ash in Korea : Potential to Secure Supply Chain for Nuclear and Small Modular Reactors Feedstock

Extraction of Scandium from Coal Ash in Korea : Potential to Secure Supply Chain for Nuclear and Small Modular Reactors Feedstock

Evaluation of Coal Repowering Option with Small Modular Reactor in South Korea

The Paris Agreement emphasizes the need to reduce greenhouse gas emissions, particularly from coal power. One suggested approach is repowering coal-fired power plants (CPPs) with small modular reactors (SMRs). South Korea plans to retire CPPs in the coming decades and requires alternative options for coal-fired energy. This study presents a scoping analysis comparing variable renewable energy (VRE) sources with SMRs for repowering CPPs in the Korean context. The analysis indicates that SMRs may be a more favorable option than VRE sources, particularly due to their load-following capabilities. In this study, two types of SMRs were investigated: high-temperature gas reactors (HTGRs) and pressurized water reactors (PWRs). HTGRs are suitable to fit the high-temperature operating conditions of steam turbines but require multiple units due to their low volumetric flow rates. PWRs, while matching the volumetric flow rate of existing CPP turbines, require additional thermal energy sources to meet the high-temperature operating conditions of steam turbines. Lastly, an analysis of necessary regulatory and legislative changes in South Korea’s nuclear framework is presented, identifying several key regulatory issues for repowering coal with nuclear energy.

Availability of Critical Benchmark Experiments for the Pebble Tanker Transportation Model for Nuclear Criticality Safety Validation of TRISO Pebbles

This study addresses the need for comprehensive investigations into TRi-structural ISOtropic (TRISO) fuel pebble transportation validation. In this work, an exploratory model, the pebble tanker(PT), was developed with the aim of facilitating the validation of nuclear criticality safety calculations in the context of industrial-scale transportation of TRISO fuel. The PT model was designed to investigate the availability and applicability of critical benchmark experiments crucial for assessing the transportation of these pebbles. This work incorporated sensitivity/uncertainty (S/U) similarity studies to quantify the applicability of critical benchmark experiments and to address nuclear data uncertainties in the context of TRISO transportation. Two container models were investigated: one for the Hermes-type pebble and one for the Pebble Bed Modular Reactor (PBMR)–type pebble. The models were simplified, considering fuel, containment, and either water or air, to enable a focus on the underlying physics of applications involving TRISO fuel pebbles using the PT model. A crucial aspect under consideration was the capacity of the transport package to hold pebbles while ensuring subcriticality in the flooded state. An approach in the criticality validation process involves assessing the similarity between systems through an integral index parameter evaluation. This involves calculating a correlation coefficient (referred to as ck) based on shared nuclear data–induced uncertainty between a benchmark experiment and the application of the PT model. To facilitate this analysis, the SCALE tools, particularly the CSAS6-Shift, TSUNAMI-3D-Shift, and TSUNAMI-IP sequences, were employed for comprehensive studies in neutronics and S/U analysis. Our findings showed that there are sufficient critical experimental benchmarks to perform this validation of the PT model in the most reactive state, i.e. when the tanker is flooded. This paper provides valuable insights into validating a transport package for Generation IV TRISO fuel pebbles.