Advanced Nuclear Technologies Research Articles

Application of the surrogate reaction ratio method to measure the (n,xp) cross sections for nuclei with A ≈ 50−60

Abstract We explore the applicability of the surrogate reaction ratio method for determining (n,xp) cross sections, where an incoming neutron induces the emission of at least one proton from a nuclear target with a mass range of A ≈ 50−60. These cross sections are relevant for advanced nuclear technologies. Our findings reveal that, under specific conditions, the surrogate reaction ratio method can yield reliable (n,xp) cross sections, similar to its success in determining (n,f) cross sections in actinides. However, not all surrogate reaction pairs meet these conditions across the entire excitation energy range, necessitating careful application of the surrogate reaction ratio method for determining (n,xp) cross sections.

Reinforcement Learning-Based Control Sequence Optimization for Advanced Reactors

The last decade has seen the development and application of data-driven methods taking off in nuclear engineering research, aiming to improve the safety and reliability of nuclear power. This work focuses on developing a reinforcement learning-based control sequence optimization framework for advanced nuclear systems, which not only aims to enhance flexible operations, promoting the economics of advanced nuclear technology, but also prioritizing safety during normal operation. At its core, the framework allows the sequence of operational actions to be learned and optimized by an agent to facilitate smooth transitions between the modes of operations (i.e., load-following), while ensuring that all safety significant system parameters remain within their respective limits. To generate dynamic system responses, facilitate control strategy development, and demonstrate the effectiveness of the framework, a simulation environment of a pebble-bed high-temperature gas-cooled reactor was utilized. The soft actor-critic algorithm was adopted to train a reinforcement learning agent, which can generate control sequences to maneuver plant power output in the range between 100% and 50% of the nameplate power through sufficient training. It was shown in the performance validation that the agent successfully generated control actions that maintained electrical output within a tight tolerance of 0.5% from the demand while satisfying all safety constraints. During the mode transition, the agent can maintain the reactor outlet temperature within ±1.5 °C and steam pressure within 0.1 MPa of their setpoints, respectively, by dynamically adjusting control rod positions, control valve openings, and pump speeds. The results demonstrate the effectiveness of the optimization framework and the feasibility of reinforcement learning in designing control strategies for advanced reactor systems.

Supercritical Water: A Simulation Study to Unravel the Heterogeneity of Its Molecular Structures.

(1) Background: In the quest to accurately model the radiolysis of water in its supercritical state, a detailed understanding of water's molecular structure, particularly how water molecules are arranged in this unique state, is essential. (2) Methods: We conducted molecular dynamics simulations using the SPC/E water model to investigate the molecular structures of supercritical water (SCW) over a wide temperature range, extending up to 800 °C. (3) Results: Our results show that at a constant pressure of 25 MPa, the average intermolecular distance around a reference water molecule remains remarkably stable at ~2.9 Å. This uniformity persists across a substantial temperature range, demonstrating the unique heterogeneous nature of SCW under these extreme conditions. Notably, the simulations also reveal intricate patterns within SCW, indicating the simultaneous presence of regions with high and low density. As temperatures increase, we observe a rise in the formation of molecular clusters, which are accompanied by a reduction in their average size. (4) Conclusions: These findings highlight the necessity of incorporating the molecular complexity of SCW into traditional track-structure chemistry models to improve predictions of SCW behavior under ionizing radiation. The study establishes a foundational reference for further exploration of the properties of supercritical water, particularly for its application in advanced nuclear technologies, including the next generation of water-cooled reactors and their small modular reactor variants that utilize SCW as a coolant.

Public–Private Partnering in Nuclear Reactor Development—Historical Review and Implications for Today

Abstract The dominant nuclear reactor technologies that comprise the current global operating fleet were developed and deployed over a relatively short, midtwentieth century, period spanning the 1950s and 60 s. Four of these technologies were deployed at fleet scales and commercially exported. The historical record indicates a remarkably consistent process of phased technology development that enabled the commercialization of designs that would define the global nuclear marketplace, beginning with research and development (R&D) and advancing through test reactors, small and large demonstration reactors, and first commercial-scale units. Following proof-of-principle R&D, historical commercialization lead times (from decision to construction of a demonstration reactor to first commercial launch) ranged from 12 to16 years for these four commercial technologies. Key factors contributing to successful commercialization included durable government support for early R&D and varying degrees of public–private partnering through commercial launch. This partnering included arrangements for technical support, siting, facility ownership, nuclear material provision, and cost sharing. The policy environment was characterized by unambiguous government support; stabile, effective and informed government program management and oversight; and flexibility in the public–private partnership arrangements to promote technology development and demonstration. Government advocacy was structured to support progressively increasing industry independence and self-sufficiency. This experience is documented and analyzed in this paper to provide salient lessons and example program elements for contemporary efforts to stimulate development and commercialization of a new generation of advanced nuclear technologies through collaboration and public–private partnerships.

The role of advanced nuclear reactors and fuel cycles in a future energy system.

Nuclear power has been an important part of the US electricity system since the 1950s and continues to be a major source of low-carbon electricity today. Despite having low emissions, high grid reliability, and an excellent track record of safety, nuclear power also demands significant time and upfront capital to deploy, can struggle to compete economically with other generation sources, has intrinsic proliferation risk by relying on fissile material for fuel, and generates radioactive waste for which there are currently no disposal sites. Given the emissions and energy security benefits of having nuclear as part of the energy mix, advanced nuclear technologies have garnered significant interest and investment in recent years. Advanced reactor designs differ from the current operating fleet and have several potential advantages, including lower cost, faster construction, smaller size, inherent safety features, and lower waste yields. Yet, many challenges related to their deployment remain, and overcoming them will dictate whether or not new nuclear technologies become a material element of the future energy infrastructure. This article synthesizes the opportunities and barriers to deploying advanced nuclear reactors and their associated fuel cycles as described in two National Academies consensus reports. It highlights the consensus recommendations that could allow these new technologies to reach commercial success as part of a long-term decarbonization strategy.

Fluoride-Salt-cooled high-Temperature Advanced Reactor (FuSTAR): An integrated nuclear-based energy production and conversion system

Based on the analysis of energy structure and the development trends of advanced nuclear energy technology, combining the complementary advantages of nuclear energy and other energy sources in China, the Fluoride-Salt-cooled high-Temperature Advanced Reactor (FuSTAR) system has been proposed. FuSTAR system is designed to address production capacity issues in areas with energy shortages or resource concentration and can be combined with high-temperature process heat to achieve high-value-added processes such as hydrogen production. In this paper, the Tri-structural isotropic fuel combined with helical cruciform elements has been studied in detail on the neutron physics and thermal-hydraulic properties, and the flow and heat transfer experiment is carried out for the first time. The multilayer nonlinear programming method has been applied to the design of thermal transport systems. Then the optimal parameters and configuration of the thermoelectric conversion system are obtained by the superstructure optimization method. The inherent safety of FuSTAR is demonstrated through deterministic safety analysis. In addition, the iodine-sulfur cycle technology and the characteristics of tritium production are also analyzed. This study highlights the significant potential of integrating nuclear energy with other energy sources in an optimized energy-production system.

The neutron time-of-flight facility n_TOF at CERN Recent facility upgrades and detector developments

Based on an idea by Carlo Rubbia, the n_TOF facility at CERN has been operating for over 20 years. It is a neutron spallation source, driven by the 20 GeV/c proton beam from the CERN PS accelerator. Neutrons in a very wide energy range (from GeV, down to sub-eV kinetic energy) are generated by a massive Lead spallation target feeding two experimental areas. EAR1, horizonal with respect to the proton beam direction is set at 185 meters from the spallation target. EAR2, on the vertical line from the spallation source, is placed at 20 m. Neutron energies for experiments are selected by the time-of-flight technique (hence the name n_TOF), while the long flight paths ensure a very good energy resolution. Over one hundred experiments have been performed by the n_TOF Collaboration at CERN, with applications ranging from nuclear astrophysics (synthesis of the heavy elements in stars, big bang nucleosynthesis, nuclear cosmo-chronology), to advanced nuclear technologies (nuclear data for applications, nuclear safety), as well as for basic nuclear science (reaction mechanisms, structure and decay of highly excited compound states). During the planned shutdown of the CERN accelerator complex between 2019 and 2021, the facility went through a substantial upgrade with a new target-moderator assembly, refurbishing of the neutron beam lines and experimental areas. An additional measuring and irradiation station (the NEAR Station) has been envisaged and its capabilities for performing material test studies and new physics opportunities are presently explored. An overview of the facility and of the activities performed at CERN is presented in this contribution, with a particular emphasis on the most relevant experiments for nuclear astrophysics.

The development of future options for aqueous recycling of spent nuclear fuels

Since 2017, the UK Government has invested in research and technology development of advanced nuclear technologies including options for the future recycling of spent nuclear fuels. Whilst the UK has previously reprocessed and recycled uranium and plutonium from spent fuels, industrial scale reprocessing has finished and future fuels are being stored ready for disposal in a deep geological repository around the end of the century (i.e.transition to the open fuel cycle). Nevertheless, it is possible that an expansion of the use of nuclear energy to help meet Net Zero carbon emission targets and changing public perceptions or geopolitical situations over this period may necessitate a return to some form of closed fuel cycle. Consequently, the Advanced Fuel Cycle Programme (AFCP) has been developing advanced recycling options using both aqueous and pyro-chemical methods that would reduce wastes, costs and environmental impacts but with enhanced flexibility and barriers against nuclear proliferation risks. As well as technology development, AFCP has developed approaches for evaluating the benefits and disbenefits of future fuel cycle options under the framework of sustainability. This article provides an overview of the progress made under AFCP on the aqueous recycling of spent fuels, including the management of secondary wastes arising from the reprocessing schemes.

Structural, physical, and radiation absorption properties of a significant nuclear power plant component: A comparison between REX-734 and 316L SS austenitic stainless steels

Abstract Austenitic stainless steels (SSs) are commonly used as in-core and surrounding structural materials in today’s industrial BWR and PWR systems. Such adaptable steels have also been the primary materials studied and used in several advanced nuclear reactor technologies, such as fast breeding and magnetic fusion reactors. In this study, some critical material properties, such as structural, physical, and radiation-shielding properties of REX-734 and 316L SS, were experimentally evaluated and compared to those of a number of other alloys. In addition to homogeneous element distribution, both alloys exhibit strong crystal orientation. The REX-734 alloy has a tensile strength of 1,259 MPa, whereas the 316L SS alloy has a tensile strength of 495 MPa. Moreover, nitrogen in the REX-734 alloy formed ultra-hard nitrides with Cr, Nb, and Si and precipitated into the structure and increased the strength. According to our findings, the mass attenuation coefficient values of the 316L SS sample were slightly higher than those of the REX-734 sample at all energies. It can be concluded that the REX-734 sample, with its exceptional strength qualities and excellent radiation attenuation capabilities, may be a viable nuclear power plant material for future investigations.

Near Infrared Spectroscopy of Fission Products in Alkali Chloride Molten Salt – Structural Interpretation and Analytical Use

Advanced nuclear technologies using high-temperature molten salts are poised to increase the efficiency, flexibility, and acceptability of nuclear energy. To realize these advances, additional understanding of the chemistry and thermochemical and thermophysical properties of the molten salt mixtures is required. Additionally, methods to rapidly and non-destructively monitor and determine the concentration and chemistry of actinides and fission products must be developed. Electronic and vibrational spectroscopy are promising methods to both interpret the structure and speciation of dissolved species in molten salts and to determine concentrations of species of interest. We have determined the molar absorbance coefficients of selected absorbance features for several lanthanides of interest in the ultraviolet, visible, and near infrared ranges and show that some NIR absorbance features, which were previously neglected as a means of concentration determination, are analytically useful. In fact, these NIR absorbance features may have advantages over UV and visible range features for concentration determination in industrial systems. Additionally, we will present our analysis of the effects of the coordination environment on lanthanide electronic structure and transitions, yielding insight into the chemistry and coordination of these elements in molten alkali halide mixtures, which is crucial for understanding the corrosion issues in these salts amongst other requirements.Acknowledgement:This research is being performed using funding received from the DOE Office of Nuclear Energy's Nuclear Energy University Programs under award DE-NE0008889 and the US Nuclear Regulatory Commission (USNRC) under contract 31310018M0032. Dr. Kenny Osborne and Ms. Nancy Hebron-Isreal serve as the program managers for the DOE and NRC awards, respectively.This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-1447692. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation, the U.S. Department of Energy, or the United States Government.

Preface: 19th International Conference on Emerging Nuclear Energy Systems (ICENES 2019)

This is an exclusively prepared special issue containing selected papers from well-established events, namely, International Conference on Emerging Nuclear Energy Systems (ICENES) and some invited papers to enrich and broaden the novelty of nuclear energy technologies and its applications. The 19th International Conference on Emerging Nuclear Energy Systems (ICENES 2019) is one of the international conference on scientific, engineering, education and other technical aspects of innovative nuclear reactor design, advanced nuclear technology, energy related technology and its applications.The conference was held in Holiday Inn, Bali, Indonesia (6-9 October 2019), organized by the Bandung Institute of Technology (ITB) and in cooperation with the International Atomic Energy Agency (IAEA). The participants come from several 14 countries and from many institutions from universities, governments, companies, society and some other organizations that shared their ideas and research results on emerging nuclear energy technologies and applications, which covered by keynote speakers, invited and contributed oral talks and poster presentations. Some selected presented paper in the conference have been elected as selected papers after reviewing process to be submitted to the Institute of Physics (IoP), Journal of Physics: Conference Series.Nuclear energy recently is recognized as secure, sustain and green energy source as an ultimate energy resource to secure the future of the mankind and its civilization. Hence, considerable research activities and international collaboration are continuing on innovative nuclear energy systems, reactor physics, radiations and its application, nuclear computational system, including fusion energy technology, fusion-fission hybrids systems, GEN-IV reactors technology, small and modular reactor (MSR) technology, space nuclear reactors, and power systems and accelerator-driven systems technologies. Some related topics are also covered related to nuclear power production; nuclear hydrogen production; hydrogen energy, energy efficiency, and management; solar energy; wind energy; hydrogen production and storage; renewable energy; fuel cells; bio-energy, etc.Finally, on behalf of the organizer and advisory board, we would like to express my sincere appreciation and gratitude to all of authors during the conference and publication processes for their valuable contributions and to the members of the committee, reviewers, and advisors for their excellent works in preparing and finalizing this document. We apologize for any inconveniences for this long process of publication due to our conditions and some restrictions as well as some difficulties during COVID19 pandemicList of Organizer, Editorial Board are available in this Pdf.

Role of the sedimentary organic matter structure and microporosity on the degradation of nonylphenol by potassium ferrate

In this study, the role of organic matter structure and microporosity in the adsorption and degradation of radioactive nonylphenol in sediments treated with potassium ferrate solutions was investigated. The demineralized fractions and acid non-hydrolyzable fractions were isolated and characterized via advanced solid-state 13C nuclear magnetic resonance and CO2 gas adsorption technology, respectively. Radioactive nonylphenol in the sediments was also fractionated into 14CO2, water-soluble residues, extractable residues, and strongly bound residues after treatment with potassium ferrate. A first-order, two-compartment kinetic model well described the mineralization and degradation kinetics of radioactive nonylphenol in the sediment (R2 > 0.99). The degradation percentages of spiked nonylphenol were highly negatively correlated with aromatic carbon, aliphatic carbon, and microporosity estimated from acid-non-hydrolyzable fractions in the bulk sediments (R2 > 0.82, p < 0.01). The percentages of adsorbed parent nonylphenol residues were highly positively correlated with aromatic carbon, aliphatic carbon, and microporosity estimated from acid-non-hydrolyzable fractions in the bulk sediments (R2 > 0.90, p < 0.01). The parent nonylphenol compound desorbed into the aqueous phase and was completely degraded. This study is the first to demonstrate the important role of aromatic carbon, aliphatic carbon, and microporosity in acid non-hydrolyzable fractions on the degradation of nonylphenol during the potassium ferrate oxidation treatment process.

Reliability estimation of an advanced nuclear fuel using coupled active learning, multifidelity modeling, and subset simulation

Tristructural isotropic (TRISO)-coated particle fuel is a robust nuclear fuel and determining its reliability is critical for the success of advanced nuclear technologies. However, TRISO failure probabilities are small and the associated computational models are expensive. We used coupled active learning, multifidelity modeling, and subset simulation to estimate the failure probabilities of TRISO fuels using several 1D and 2D models. With multifidelity modeling, we replaced expensive high-fidelity (HF) model evaluations with information fusion from two low-fidelity (LF) models. For the 1D TRISO models, we considered three multifidelity modeling strategies: only Kriging, Kriging LF prediction plus Kriging correction, and deep neural network (DNN) LF prediction plus Kriging correction. While the results across these multifidelity modeling strategies compared satisfactorily, strategies employing information fusion from two LF models called the HF model least often. Next, for the 2D TRISO model, we considered two multifidelity modeling strategies: DNN LF prediction plus Kriging correction (data-driven) and 1D TRISO LF prediction plus Kriging correction (physics-based). The physics-based strategy, as expected, consistently required the fewest calls to the HF model. However, the data-driven strategy had a lower overall simulation time since the DNN predictions are instantaneous, and the 1D TRISO model requires a non-negligible simulation time.

Stochastic core–shell (SCS) approximation for accelerated atomistic modeling of irradiation-induced damage in materials

Understanding irradiation effects on the structure and properties of materials is crucial for the development of advanced nuclear technologies. Molecular dynamics (MD) simulations are suitable for the study of irradiation-induced damage in materials with atomistic resolution. However, MD simulation of structural damage through collision cascades is computationally expensive, and therefore it is impractical for the study of cumulative irradiation-induced effects in materials due to long-term exposure to irradiation. To overcome this limitation, we propose a stochastic core–shell (SCS) approximation of collision cascades, which is capable of reproducing the defect structures produced by primary radiation damage in MD simulations. The SCS retains the characteristic damage for a given primary knock-on atom energy and system temperature, but without the explicit simulation of the preceding collision cascade. Thus, the method provides an efficient approach to investigate irradiation-induced damage in materials using MD simulations. We demonstrate the application of the SCS method to the investigation of irradiation-induced microstructural effects in α-zirconium.

Projected electricity costs in international nuclear power markets

The nuclear power industries in member countries of the Organisation for Economic Cooperation and Development (OECD) have lost global nuclear market share to Russian and Chinese firms. A recent OECD report claims, under restrictive assumptions, that (1) nuclear power units using OECD member country technologies are competitive with those using Russian and Chinese technologies, and (2) nuclear power has lower expected average costs than coal (with carbon dioxide taxes) and renewables. OECD based firms are hoping to catch up to Russia and China with Small Modular Reactors and advanced nuclear technologies. But unless OECD member governments and utilities are willing to invest hundreds of billions of dollars in financing their nuclear industries’ projects, it will be difficult to stop Russian and/or Chinese dominance of the global nuclear industry after 2030.

Constructing nuclear responsibility in US–India relations

Abstract In 2005, the United States recognized India as a ‘responsible state with advanced nuclear technology’. How did India go from pariah to a legitimate nuclear state? This article historicizes the concept of nuclear responsibility to explain India's shifting place in the nuclear regime. Existing perspectives view responsibility as a function of discrete state behaviors to the detriment of understanding the relationship between power and responsibility as a discourse. This article tracks the evolving discourse of early proliferators, such as the US, UK and France, who legitimated their possession of nuclear weapons by linking responsibility with deterrence. In its early nuclear history, India challenged these hegemonic perspectives but more recently adopted the deterrence model of responsibility to be granted recognition and legitimacy in the global nuclear regime. The article concludes that nuclear states’ success in linking deterrence with responsibility complicates the place of disarmament as an alternative nuclear responsibility discourse. Tying deterrence to responsibility reshaped the global order around the continual presence of nuclear weapons, narrowing moral agency and limiting a nuclear weapon-free future. Reclaiming responsibility will require moving beyond the typical state-centric politics of blame towards institutional and structural approaches to moral agency.

The Versatile Test Reactor Project: Mission, Requirements, and Description

The mission of the U.S. Department of Energy (DOE) Office of Nuclear Energy is to advance nuclear power to meet the nation’s energy, environmental, and national security needs. Advanced nuclear technology development, as well as support for the current nuclear power industry, requires a robust infrastructure for experimentation, testing, design evolution, and component qualification. The current lack of fast neutron spectrum testing capabilities has been identified as a significant gap in the U.S. infrastructure that impedes the development of next-generation nuclear reactors—many of which require a fast neutron spectrum for operation—and equally impacts the United States’ ability to regain global technology leadership in this arena. To close the gap and support advanced technology development, the DOE has established the Versatile Test Reactor (VTR) project to provide high-performance testing capability, specifically, a fast neutron source to develop, test, and qualify advanced fuels and materials for the next generation of advanced reactors and existing commercial reactors. This paper describes the establishment of the project, the identification of its mission and requirements, and the design approach and status.

Constraints on the dipole photon strength for the odd uranium isotopes

Background: The photon strength functions (PSFs) and nuclear level density (NLD) are key ingredients for calculation of the photon interaction with nuclei, in particular the reaction cross sections. These cross sections are important especially in nuclear astrophysics and in the development of advanced nuclear technologies. Purpose: The role of the scissors mode in the M1 PSF of (well-deformed) actinides was investigated by several experimental techniques. The analyses of different experiments result in significant differences, especially on the strength of the mode. The shape of the low-energy tail of the giant electric dipole resonance is uncertain as well. In particular, some works proposed a presence of the E1 pygmy resonance just above 7 MeV. Because of these inconsistencies additional information on PSFs in this region is of great interest. Methods: The γ-ray spectra from neutron-capture reactions on the U234, U236, and U238 nuclei have been measured with the total absorption calorimeter of the n_TOF facility at CERN. The background-corrected sum-energy and multi-step-cascade spectra were extracted for several isolated s-wave resonances up to about 140 eV. Results: The experimental spectra were compared to statistical model predictions coming from a large selection of models of photon strength functions and nuclear level density. No combination of PSF and NLD models from literature is able to globally describe our spectra. After extensive search we were able to find model combinations with modified generalized Lorentzian (MGLO) E1 PSF, which match the experimental spectra as well as the total radiative widths. Conclusions: The constant temperature energy dependence is favored for a NLD. The tail of giant electric dipole resonance is well described by the MGLO model of the E1 PSF with no hint of pygmy resonance. The M1 PSF must contain a very strong, relatively wide, and likely double-resonance scissors mode. The mode is responsible for about a half of the total radiative width of neutron resonances and significantly affects the radiative cross section.3 MoreReceived 24 August 2021Accepted 31 January 2022DOI:https://doi.org/10.1103/PhysRevC.105.024618Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasElectromagnetic transitionsModels & methods for nuclear reactionsNeutron physicsNuclear reactionsRadiative captureResonance reactionsPropertiesA ≥ 220TechniquesNuclear data analysis & compilationNuclear Physics

Numerical analysis of the alanine response using Monte Carlo: Correlation with experimental results

International centers based on research reactors (ICERR) project supported by IAEA, offers training and research in the application of advanced nuclear reactor technology. In this context of the project, alanine dosimeters were irradiated under mixed neutron/gamma irradiation in the core of the MINERVE research reactor at the CEA Cadarache. The integrated dose of the alanine was measured by electron spin resonance spectrometry with reference to an absorbed dose in water from a 60Co gamma-ray beam. Neutron and gamma dose components were calculated using the MCNP code. The neutron dose and relative effectiveness (REn) for neutrons was evaluated using FLUKA code and Track Structure Theory (TST) formulations of alanine response towards irradiations with ions produced by neutron interactions with alanine. REn values were found to be between 0.516 and 0.538. The measured dose was compared to the calculation results. The best agreement between the alanine integral measurements and model predictions (0.4%) was obtained by using the Cucinotta alanine detector response model.

Transient analysis of the main heat-transfer system of the pool-type sodium-cooled fast reactor

<p indent="0mm">Sodium-cooled fast reactors are the first choice of the fourth generation of advanced nuclear energy systems. They have attracted significant attention in the development of advanced nuclear energy technology owing to their advantages of proliferative nuclear fuel, transmutation of radioactive waste, and high thermal efficiency power generation. The design and construction of the secondary sodium-cooled fast reactor are ongoing in China. The physical characteristics of fast neutrons and the special thermal, physical, and chemical properties of liquid sodium metal cause special and complex scientific problems in the design of sodium-cooled fast reactors. In this study, taking the energy transfer process of sodium-cooled fast reactors as the object, we establish mathematical and physical models for analyzing large-scale transients in various energy transfer and conversion processes. The model is verified and validated by the natural circulation test of the Phoenix reactor and the international benchmark of the fast flux test facility loss in flow tests. The trend of the calculated values is consistent with that of the test data, and the results are in good agreement. For a typical pool-type sodium-cooled fast reactor, four types of transient events in the power plant are determined by engineering evaluation and deductive analysis. Among them, there are nine normal operation transients, 23 expected transients, 10 abnormal transients, and 7 emergency transients. Based on the established mathematical and physical models, the analysis results of each type of typical transient are given, which provide an important basis for the design of the system and equipment/components and lay a scientific and technological foundation for completing the design of the transient condition and operation mode of the sodium-cooled fast reactor as well as safety evaluation.