Materials for future nuclear energy systems must operate under more extreme conditions than those in current Gen II or Gen III systems. These conditions include higher temperature, higher dpa, and ...more corrosive environments. This paper reviews some of the fuels and structural materials used in advanced nuclear energy systems and identifies promising candidates for these systems. Fuel systems includes metallic fuels for the sodium cooled reactor, TRISO-coated particle fuel for the high temperature gas reactor, molten salt reactor fuels, and accident tolerant fuels for light water reactors. Structural materials applications include the sodium fast reactor, lead fast reactor, high temperature gas reactor, molten salt reactor and extended life light water reactors. A final section focuses on plasma-facing and blanket materials for deuterium-tritium fusion reactors.
Molten salt reactors (MSRs) are being considered as one of the potential nuclear options to meet future energy demands. While the MSR designs are drastically different from the more traditional light ...water reactor, many of the waste streams are similar between the concepts. The purpose of this paper is to outline strategies for the treatment and processing of MSR-type wastes from concepts of reconditioning and recycle of certain components to partitioning and direct immobilization of other waste components. To help bridge science and technology gaps, knowledge gained from similar efforts such as pyroprocessing of Experimental Breeder Reactor II salt wastes can be leveraged to develop concept-to-disposition pathways.
We describe measurements of fission product data at Los Alamos that are important for determining the number of fissions that have occurred when neutrons are incident on plutonium and uranium ...isotopes. The fission-spectrum measurements were made using a fission chamber designed by the National Institute for Standards and Technology (NIST) in the BIG TEN critical assembly, as part of the Inter-laboratory Liquid Metal Fast Breeder Reactor (LMFBR) Reaction Rate (ILRR) collaboration. The thermal measurements were made at Los Alamos' Omega West Reactor. A related set of measurements were made of fission-product ratios (so-called R-values) in neutron environments provided by a number of Los Alamos critical assemblies that range from having average energies causing fission of 400-600 keV (BIG TEN and the outer regions of the Flattop-25 assembly) to higher energies (1.4-1.9 MeV) in the Jezebel, and in the central regions of the Flattop-25 and Flattop-Pu, critical assemblies. From these data we determine ratios of fission product yields in different fuel and neutron environments (Q-values) and fission product yields in fission spectrum neutron environments for {sup 99}Mo, {sup 95}Zr, {sup 137}Cs, {sup 140}Ba, {sup 141,143}Ce, and {sup 147}Nd. Modest incident-energy dependence exists for the {sup 147}Nd fission product yield; this is discussed in the context of models for fission that include thermal and dynamical effects. The fission product data agree with measurements by Maeck and other authors using mass-spectrometry methods, and with the ILRR collaboration results that used gamma spectroscopy for quantifying fission products. We note that the measurements also contradict earlier 1950s historical Los Alamos estimates by {approx}5-7%, most likely owing to self-shielding corrections not made in the early thermal measurements. Our experimental results provide a confirmation of the England-Rider ENDF/B-VI evaluated fission-spectrum fission product yields that were carried over to the ENDF/B-VII.0 library, except for {sup 99}Mo where the present results are about 4%-relative higher for neutrons incident on {sup 239}Pu and {sup 235}U. Additionally, our results illustrate the importance of representing the incident energy dependence of fission product yields over the fast neutron energy range for high-accuracy work, for example the {sup 147}Nd from neutron reactions on plutonium. An upgrade to the ENDF library, for ENDF/B-VII.1, based on these and other data, is described in a companion paper to this work.
Molten Salt Reactors is a comprehensive reference on the status of molten salt reactor (MSR) research and thorium fuel utilization. There is growing awareness that nuclear energy is needed to ...complement intermittent energy sources and to avoid pollution from fossil fuels. Light water reactors are complex, expensive, and vulnerable to core melt, steam explosions, and hydrogen explosions, so better technology is needed. MSRs could operate safely at nearly atmospheric pressure and high temperature, yielding efficient electrical power generation, desalination, actinide incineration, hydrogen production, and other industrial heat applications. Coverage includes: * Motivation -- why are we interested? * Technical issues – reactor physics, thermal hydraulics, materials, environment, … * Generic designs -- thermal, fast, solid fuel, liquid fuel, … * Specific designs – aimed at electrical power, actinide incineration, thorium utilization, … * Worldwide activities in 23 countries * Conclusions This book is a collaboration of 58 authors from 23 countries, written in cooperation with the International Thorium Molten Salt Forum. It can serve as a reference for engineers and scientists, and it can be used as a textbook for graduate students and advanced undergrads. Molten Salt Reactors is the only complete review of the technology currently available, making this an essential text for anyone reviewing the use of MSRs and thorium fuel, including students, nuclear researchers, industrial engineers, and policy makers. * Written in cooperation with the International Thorium Molten-Salt Forum * Covers MSR-specific issues, various reactor designs, and discusses issues such as the environmental impact, non-proliferation, and licensing * Includes case studies and examples from experts across the globe
Nuclear energy is an important ultra-low carbon electricity source. Engineering demonstration reactors, such as Shippingport for Pressurized Water Reactor technology, have been used to advance ...nuclear reactor technology to deployment. It may be necessary to develop similar engineering demonstration reactors for other reactor concepts that have not yet been built. This paper reviews the historical role of engineering demonstration reactors and highlights the potential for future engineering demonstrations of Fluoride Salt-Cooled High Temperature Reactors (FHRs) and Molten Chloride Fast Reactors (MCFRs). Future engineering demonstration reactors could significantly accelerate deployment of larger-scale FHRs and MCFRs by the advanced nuclear industry via cost and risk reduction. Experience in the United States shows that sustained investment in a public-private partnership, such as the current Advanced Reactor Demonstration Program, is essential for deployment of advanced reactor technologies that have never been built before. The National Reactor Innovation Center at Idaho National Laboratory and Clinch River Site near Oak Ridge National Laboratory are examples of ideal locations for these demonstrations.
•Engineering demonstration reactors are key to the development of reactor technology.•All reactor technologies in the US were developed by public-private partnerships.•The US ARDP aims to bootstrap deployment of new reactor technologies.
The Versatile Test Reactor (VTR) currently under development is a 300 MWth sodium-cooled fast reactor (SFR) fueled with ternary metal alloy fuel, which aims to accelerate the testing of advanced ...nuclear fuels, materials, instrumentation, and sensors in high flux environments that are necessary to license the next generation of advanced reactor concepts. To support the VTR design process, uncertainties associated with the nuclear data has been propagated through the reactor core neutronics calculation to global parameters of interest, such as the core multiplication factor, kinetic parameters, and various reactivity feedback coefficients, following the sensitivity based uncertainty propagation approach. By folding the sensitivity coefficients, separately computed by the generalized perturbation theory code PERSENT and Monte Carlo code Serpent 2, with the variance–covariance matrices from COMMARA-2.0, we obtain the reaction-wise, isotope-wise, and overall uncertainties for each response of interest due to nuclear data uncertainty. With Serpent 2, the statistical error of the uncertainty is obtained by propagating the statistical error of the sensitivity coefficients through the same process using a newly developed uncertainty propagation method. From both codes, the overall top uncertainty contributors are found to be the cross section of Fe-56 elastic scattering, Na-23 elastic scattering, and U-238 inelastic scattering. The large contributions of the Fe-56 elastic scattering cross sections to global parameters are due to its relatively large relative uncertainty of 5–10% in nuclear data and the large volume of Fe-containing reflector assemblies in the fairly compact VTR core design. Both codes agreed well for the overall uncertainty estimates of all responses of interest, except the delayed neutron fraction, prompt neutron generation time, and the coolant density feedback coefficient, where Serpent 2 yielded a much larger value than PERSENT due to the large statistical error of sensitivity coefficients. The calculated uncertainties are also compared to those associated with other SFR cores. Another outcome of this study is a variance–covariance matrix of reactivity coefficients, which can be used in the subsequent uncertainty propagation to the system level to investigate the impact of identified uncertainties on system responses in the safety analysis.
Analysts and decision makers frequently want estimates of the cost of technologies that have yet to be developed or deployed. Small modular reactors (SMRs), which could become part of a portfolio of ...carbon-free energy sources, are one such technology. Existing estimates of likely SMR costs rely on problematic top-down approaches or bottom-up assessments that are proprietary. When done properly, expert elicitations can complement these approaches. We developed detailed technical descriptions of two SMR designs and then conduced elicitation interviews in which we obtained probabilistic judgments from 16 experts who are involved in, or have access to, engineering-economic assessments of SMR projects. Here, we report estimates of the overnight cost and construction duration for five reactor-deployment scenarios that involve a large reactor and two light water SMRs. Consistent with the uncertainty introduced by past cost overruns and construction delays, median estimates of the cost of new large plants vary by more than a factor of 2.5. Expert judgments about likely SMR costs display an even wider range. Median estimates for a 45 megawatts-electric (MW ₑ) SMR range from $4,000 to $16,300/kW ₑ and from $3,200 to $7,100/kW ₑ for a 225-MW ₑ SMR. Sources of disagreement are highlighted, exposing the thought processes of experts involved with SMR design. There was consensus that SMRs could be built and brought online about 2 y faster than large reactors. Experts identify more affordable unit cost, factory fabrication, and shorter construction schedules as factors that may make light water SMRs economically viable.
•SFRs have shown a remarkable operational performance in the last 10years.•Real reliability of BN-600 is comparable to German LWRs.•Inherent safety of well-balanced SFRs has been ...demonstrated.•Distributed moderator opens the possibility to improve inherent safety.
The reasons for the renewed interest in fast reactors and an overview of the progress in sodium cooled fast reactor operation in the last ten years are given. The excellent operational performance of sodium cooled fast reactors in this period is highlighted as a sound basis for the development of new fast reactors. The operational performance of the BN-600 is compared and evaluated against the performance of German light water reactors to assess the reliability. The relevance of feedback effects for safe reactor design is described, and a new method for the enhancement of feedback effects in fast reactors is proposed. Experimental reactors demonstrating the inherent safety of advanced sodium cooled fast reactor designs are described and the potential safety improvements resulting from the use of fine distributed moderating material are discussed.
One sentence summary: Operating fast reactors have shown excellent in-service behavior within the last 10years, new designs and methods are available to significantly improve safety.
In a molten salt nuclear reactor system, the redox potential must be controlled for mitigating corrosion of structural materials. The paper presented a critical review on the available knowledge of ...redox potential control in molten fluoride salt systems. The major phenomena that affect the redox potential and material corrosion are fission, TF production by transmutation, and salt contamination with metal fluorides or other oxidizing impurities. Redox potential control methodologies include gas sparging, contacting the salt with a reducing metal, and adding soluble salt redox buffers to the salt. Redox potential measurement technologies include electrochemical sensors and optical spectroscopy. The paper also analyzed the current technology issues and recommended near future studies.
Solar thermochemistry is a technology that has been demonstrated to contain a high potential development capability. In order to carry out efficient solar chemical reactions, optimized reactors ...adapted to each chemical process are necessary. In last 30 years many solar reactors of different configurations, performances and sizes have been designed and fabricated by the main solar chemistry research groups. Among them, directly irradiated particles solar reactors operate in a high temperature range that usually correspond to gas–solid thermochemical reactions. This work compiles more than 20 directly irradiated particles reactors designed, constructed and experimentally investigated in the last 30 years. Their description, schemes and main parameters of their performance are given. Detected problems associated are also mentioned. Reactors are classified from the point of view of chemical engineering in entrained, fluidized and stacked beds. Finally, a summary of the main characteristics of reviewed reactors is provided.
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