Development Of Reactor Research Articles

Best Practices for Experiments and Reports in Photocatalytic Methane Conversion

AbstractEfficiently converting methane into valuable chemicals via photocatalysis under mild condition represents a sustainable route to energy storage and value‐added manufacture. Despite continued interest in this area, the achievements have been overshadowed by the absence of standardized protocols for conducting photocatalytic methane oxidation experiments as well as evaluating the corresponding performance. In this review, we present a structured solution aimed at addressing these challenges. Firstly, we introduce the norms underlying reactor design and outline various configurations in the gas–solid and gas–solid–liquid reaction systems. This discussion helps choosing the suitable reactors for methane conversion experiments. Subsequently, we offer a comprehensive step‐by‐step protocol applicable to diverse methane‐conversion reactions. Emphasizing meticulous verification and accurate quantification of the products, this protocol highlights the significance of mitigating contamination sources and selecting appropriate detection methods. Lastly, we propose the standardized performance metrics crucial for evaluating photocatalytic methane conversion. By defining these metrics, the community could obtain the consensus of assessing the performance across different studies. Moving forward, the future of photocatalytic methane conversion necessitates further refinement of stringent experimental standards and evaluation criteria. Moreover, development of scalable reactor is essential to facilitate the transition from laboratory proof‐of‐concept to potentially industrial production.

A multi-criteria decision-making approach for pressurized water reactor based on hesitant fuzzy-improved cumulative prospect theory and 2-additive fuzzy measure

As one of the world's largest energy consumers, China has paid much attention to the development of non-fossil energy sources. The nuclear power is regarded as the top priority for development due to its remarkable ecological and economic advantages. Given the large investment, long lifecycle, and rigorous quality control, the conceptual design plays a critical role in the pressurized water reactor development. Multitudinous design alternatives are presented at this stage and it is essential to develop an advanced evaluation approach. Hence, this work proposes a multi-criteria decision-making approach for pressurized water reactor based on hesitant fuzzy-improved cumulative prospect theory and 2-additive fuzzy measure. Firstly, considering the inherent uncertainty and cognitive biases of nuclear power experts, cumulative prospect values are calculated for design alternatives by adopting dual prospect reference points and two-tuple entropy measure under a hesitant fuzzy environment. Secondly, a linear programming model based on bidirectional projection measures is constructed to eliminate the discordance between the independent criteria assumption and interdependent evaluation information. This model helps to identify optimal 2-additive fuzzy measures, which serve as the basis for determining the Shapley importance and interaction indices of evaluation criteria. Then, taking Shapley interaction indices modification into account, a quadratic programming model based on the global criterion method is built. Finally, 2-additive Choquet integral-based TOPSIS method is proposed to select the optimal design alternative. A case study on the essential service water system is implemented to demonstrate the reliability and superiority of the proposed approach.

Optimizing humic acid breakdown and methane production via semiconductor-assisted photo-anaerobic digestion

Humic acids (HAs), whether naturally present in anaerobic digestion (AD) substrates or HAs newly formed during fermentation, can become inhibitory to methanogenesis as their concentrations reach certain levels. This study delved extensively into the mechanism underlying the alleviation of HAs inhibition in photo-AD by N-doped carbon quantum dots (NCQDs). These NCQDs were efficiently synthesized from straw using an environmentally friendly pretreatment method. Our proposed method harnessed the combined effect of light exposure and NCQDs, resulting in synergistic enhancement of the cumulative CH4 yield within the HA-inhibited AD system, achieving a remarkable yield of 293.7 ± 17.7 mL/g VS. In-depth analyses were conducted on the remaining dissolved organic matter (DOM) within digesters using 3D-EEM and ESI FT-ICR MS. Simultaneously, the remaining HAs were extracted and subjected to FT-IR analysis. The findings revealed that NCQDs effectively degraded humic acid-like components in DOM into smaller, more manageable micromolecules characterized by lower carbon numbers and reduced double bond equivalent. Additionally, under the influence of light, NCQDs promoted the degradation of aromatic components within HAs. These resulting micromolecules were made readily available for utilization by microorganisms, further contributing to methanogenesis. Furthermore, photoelectrochemical analysis and specific gene qPCR analysis revealed that the photoelectrons from NCQDs and HAs were received and transferred by Ech (electron acceptors) for methanogenesis. Remarkably, this methanogenesis pathway, akin to photosynthesis, played a pivotal and transformative role in the photo-AD system. This work comprehensively revealed the remarkable potential mechanism of semiconductors within the photo-AD system, offering profound insights that can catalyze the development of innovative AD reactors and semiconductor accelerators.

CFD simulation of heat and mass transfer processes in a metal hydride hydrogen storage system, taking into account changes in the bed structure

CFD modelling of heat-and-mass transfer in metal hydride (MH) beds is an important step in the development and optimisation of MH reactors for hydrogen storage, compression and separation/purification. In the existing models, the mass conservation equation includes the density of solid in the non-hydrogenated (ρs) and hydrogen-saturated (ρss) states. To provide constant porosity of the MH bed during H2 absorption/desorption, assumption ρs<ρss is typically taken. However, this assumption contradicts to well-known fact that hydrogenation of hydride-forming alloys is accompanied by the expansion of crystal lattice of the metallic matrix and, therefore, by the decrease of the solid density by 15–25%.This work presents results of the modelling which takes this effect into account. The model assumes that the density of the MH changes linearly as the starting hydride-forming alloy is saturated with hydrogen, while the volume of the MH bed remains constant. The last assumption is a limiting estimation because it provides the maximum possible reduction in the porosity during H2 absorption process.The model was validated using published experimental data on a cylindrical MH reactor filled with 422 g of LaNi5. It was shown that accounting the realistic changes in the MH density can significantly affect the simulation results.

Withdrawn: Co-hydropyrolysis of sewage sludge and algae biomass: A systematic study on thermal decomposition behaviors and kinetic characteristics

In the present study, a thermogravimetric analyzer was used to assess the co-hydropyrolysis kinetics of sewage sludge and algae biomass. Three isoconversional methods (Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa, and Friedman) and one model-fitting method (DAEM) accurately fitted the experimental data at three heating rates (10, 30 and 50 °C/min) between 10 % and 90 % conversion. These methods agree with the trends shown by the activation energy (Ea) distribution calculated, with fluctuations between 120 and 330 kJ/mol. Compared with the pyrolysis of a single sample, the reaction activation energy of sludge and algae was significantly reduced in the case of co-pyrolysis. When 20 % algae are added, the activation energy is only 50 % of the original, below 100KJ/mol. Physiochemical characterization confirmed that they have the potential for fuel and energy production. Kinetic parameters fitted by DAEM were successfully verified at the highest heating rate studied and the linear fitting curve of DAEM is better. The kinetic results confirm that the activation energy is related to the conversion rate, and the change of activation energy and conversion rate indicates that the biomass undergoes a very complex pyrolysis process. In this study, the mixing of sewage sludge and algal biomass in hydrogen atmosphere can significantly change the energy required for pyrolysis reaction, which provides data support for the development, design and optimization of pyrolysis reactors. According to the change of weight loss and activation energy, it provides support for the feed amount, reaction temperature and gas flow of the pyrolysis furnace in the process of pyrolysis reaction.

Molecular dynamics simulations for the prediction of thermophysical properties of plutonium-based molten salts

Molten salt nuclear reactors are promising technologies for sustainable energy sources. In this context, understanding the physicochemical properties of molten salts is essential to the development, usage, and maintenance of reactors. Classical molecular simulations allow estimating the macroscopic properties of molten salts at a relatively low computational cost. In this work, we develop a new force field for plutonium-based molten salts. We validate our classical model by comparing molecular dynamics results with experimental measurements, obtaining a quantitative agreement. Our work demonstrates the reliability and transferability of classical force fields to represent the physicochemical properties of molten salts.

Carbon dioxide hydrogenation to methanol by flame-deposited CuO/ZrO2-polymer membrane reactors

Carbon dioxide hydrogenation for methanol synthesis, within the framework of carbon dioxide utilization represents a promising strategy. Nevertheless, high conversion of carbon dioxide into methanol presents significant challenges, primarily arising from thermodynamic constraints and catalyst deactivation due to the formation of water as a by-product. In response to these challenges, this investigation focused on the development of an innovative hybrid catalytic membrane reactor utilizing flexible polymeric membranes with flame-made catalysts. The nanostructured CuO/ZrO2 thin layers were synthesized by flame spray pyrolysis and directly deposited on two polyimide polymers and polybenzimidazole membranes. The CuO/ZrO2-polymer membranes are reduced by H2 at 300 °C resulting in Cu/ZrO2-polymer nanocomposites. This novel hybrid membrane design facilitated the efficient separation of by-product water from the reaction environment, effectively promoting carbon dioxide conversion and ultimately leading to enhanced methanol production rate. At 200 °C and 20 bar, these catalytic membrane reactors demonstrate exceptional performance, achieving 113 % improvement in carbon dioxide conversion and a remarkable 106 % increase in methanol production rate compared to conventional catalytic fixed bed reactors. Overall, the catalytic membrane, synthesized using flame spray pyrolysis, has shown long-term stability and ability to suppress catalyst deactivation caused by water, ensuring sustained catalyst stability throughout the reaction.

Precious metal-based Catalytic Membrane Reactors for continuous flow catalytic hydrodechlorination

This work is focused on the development of Catalytic Membrane Reactors (CMRs) comprising precious metals as active phases for a comparative assessment in continuous-flow catalytic hydrodechlorination (HDC). HDC has proved its remarkable potential for application as polishing step in drinking water treatment plants, but studies operating in continuous mode are scarce. Preliminary experiments were conducted in batch operation using Pd/Al2O3, Rh/Al2O3 and Pt/Al2O3 powder catalysts to evaluate the influence of the active phase on the removal of prochloraz (PCZ) (100 μg L−1), a pesticide listed on the EU Watch List (2022/1307), by HDC. PCZ removal was successfully described by a pseudo-first order kinetic equation and reaction pathways were proposed. Among the catalysts tested, Pt-based suffered a significant deactivation, not warranting the elimination of this micropollutant. Pd/Al2O3 exhibited a faster removal of PCZ than Rh/Al2O3, while this catalyst resulted in further hydrogenation of the non-chlorinated reaction product. Accordingly, different CMRs were developed by decorating cylindrical inert porous alumina membranes with Pd, Rh, and a combination of Pd-Rh as active phases (∼1% wt.). All CMRs showed a remarkable stability along 100 h on stream, being Pd/CMR be the most effective, with a pseudo-first order rate constant value of 0.062 min−1. An assessment of the impact of operating conditions (aqueous flow rate, PCZ initial concentration, temperature and H2 flow rate) was conducted using the Pd/CMR, which notably remained stable for 450 h on stream. The versatility of the system was finally demonstrated in tap water, achieving a steady-state PCZ conversion close to 95 %.

From Atomic-Level Synthesis to Device-Scale Reactors: A Multiscale Approach to Water Electrolysis.

ConspectusThe development of an advanced energy conversion system for water electrolysis with high efficiency and durability is of great significance for a hydrogen-powered society. This progress relies on the fabrication of electrocatalysts with superior electrochemical performance. Despite decades of advancements in exploring high-performance noble and non-noble metal electrocatalysts, several challenges persist at both the micro- and macrolevels in the field of water electrolysis.At the microlevel, which encompasses electrocatalyst synthesis and characterization, design strategies for high-performance electrocatalysts have primarily focused on interface chemical engineering. However, comprehensive understanding and investigation of interface chemical engineering across various length scales, from micrometers to atomic scales, are still lacking. This deficiency hampers the rational design of catalysts with optimal performance. Under harsh reaction conditions, such as high bias potential and highly acidic or alkaline media, the surface of catalyst materials is susceptible to undergoing "reconstruction", deviating from what is observed through ex situ characterization techniques postsynthesis. Conventional ex situ characterization methods do not provide an accurate depiction of the catalyst's structural evolution during the electrocatalytic reaction, hindering the exploration of the catalytic mechanism.At the macrolevel, pertaining to catalysis-performance evaluation systems and devices, traditional laboratory settings employ a conventional three-electrode or two-electrode system to assess the catalytic performance of electrocatalysts. However, this approach does not accurately simulate hydrogen production under realistic industrial conditions, such as elevated temperatures (60-70 °C), high current densities exceeding 0.5 A cm-2, and flowing electrolytes. To address this limitation, it is crucial to develop testing equipment and methodologies that replicate the actual industrial conditions.In this Account, we propose a multiscale research framework for water electrolysis, spanning from microscale synthesis to macroscale scaled reactor design. Our approach focuses on the design and evaluation of high-performance HER/OER (hydrogen evolution reaction/oxygen evolution reaction) electrocatalysts, incorporating the following strategies: Leveraging principles of interface chemical engineering across various length scales (micrometers, nanometers, and atoms) enables the design of catalyst materials that enhance both activity and durability. This approach provides a comprehensive understanding of the intricate interplay between the catalyst structure and activity, implementing in situ/operando characterization techniques to monitor dynamic interfacial reactions and surface reconstruction processes. This facilitates a profound exploration of catalytic reaction mechanisms, offering insights into the catalyst's structural evolution during the electrocatalytic reaction. We construct a laboratory-scale membrane electrode assembly (MEA) electrochemical reactor capable of operating at high current densities (>1 A cm-2) to evaluate the electrocatalytic performance under simulated industrial conditions. This ensures objective and authentic assessments of the catalyst application potential. Throughout the following sections, we illustrate the application of interface chemical engineering on different length scales in designing diverse electrocatalyst materials. We rely on in situ characterization techniques to gain a profound understanding of the mechanisms behind the HER and OER. Additionally, we describe the development of both acidic and alkaline MEA electrochemical reactors to enhance the precision of electrocatalytic performance evaluation. Finally, we provide a concise overview of the challenges and opportunities in this field.

Development and Performance Evaluation of a Low-Cost Batch Torrefaction Reactor

Development and Performance Evaluation of a Low-Cost Batch Torrefaction Reactor

Community Governance for Small Modular Reactor (SMR) Development: Lessons from Northern and Indigenous Energy Projects

Community Governance for Small Modular Reactor (SMR) Development: Lessons from Northern and Indigenous Energy Projects

Utilizing anaerobic substrate distribution for growth of aerobic granular sludge in continuous-flow reactors

The development of continuous flow reactors (CFRs) employing aerobic granular sludge (AGS) for the retrofit of existing wastewater treatment plants (WWTPs) using a continuous-flow activated sludge (CFAS) system has garnered increasing interest. This follows the worldwide adoption of AGS technology in sequencing batch reactors (SBRs). The better settleability of AGS compared to AS allows for process intensification of existing wastewater treatment plants without the difficult conversion of often relatively shallow CFRs to deeper AGS-SBRs.To retrofit existing CFAS systems with AGS, achieving both increased hydraulic capacity and enhanced biological nutrient removal necessitates the formation of granular sludge based on the same selective pressures applied in AGS-SBRs. Previous efforts have focussed mainly on the selective wasting of flocculent sludge and retaining granular sludge to drive aerobic granulation.In this study a pilot-scale CFR was developed to best mimic the implementation of the granulation mechanisms of full-scale AGS-SBRs. The pilot-scale reactor was fed with pre-settled municipal wastewater. We established metrics to assess the degree to which the proposed mechanisms were implemented in the pilot-scale CFR and compared them to data from full-scale AGS-SBRs, specifically with respect to the anaerobic distribution of granule forming substrates (GFS). The selective pressures for granular sludge formation were implemented through inclusion of anaerobic upflow selectors with a water depth of 2.5 meters, which yielded a sludge with properties similar to AGS from full-scale SBRs. In comparison to the CFAS system at Harnaschpolder WWTP treating the same pre-settled wastewater, a more than twofold increase in volumetric removal capacity for both phosphorus and nitrogen was achieved. The use of a completely mixed anaerobic selector, as opposed to an anaerobic upflow selector, caused a shift in EBPR activity from the largest towards the smallest size class, while nitrification was majorly unaffected. Anaerobic selective feeding via bottom-feeding is, therefore, favorable for the long-term stability of AGS, especially for less acidified wastewater. The research underlines the potential of AGS for enhancing the hydraulic and biological treatment capacity of existing CFAS systems.

Dual enzyme compartmentalization in a pH-responsive membrane: A way to tune enzymatic reactions in biocatalytic membranes

In this work, the use of a pH-responsive isoporous membrane allowed the compartmentalization of two different enzymes, one on the surface and the other in the pores of the membrane. This intensified and compartmentalized enzyme-loaded membrane system allowed the two enzymatic reactions to be modulated based on a pH shift. The chosen enzymes are pectinase and β-glucosidase, enzymes commonly used in biorefinery, whose optimum pH (3 and 6.5, respectively) is in the range where membrane pore closing (pH < 4) and opening is observed. Pectinase is covalently bound to the membrane surface at pH 3 while the pores are closed and is used to control the membrane fouling due to pectin accumulation during plant material processing. β-glucosidase is immobilized in the membrane pores at pH 6.5 (open pores) and is used to catalyze the reaction of oleuropein into the phytotherapeutic oleuropein aglycone. The different localization of the two enzymes was demonstrated by AFM, immunolocalization and SEM, confocal microscopy and XPS. In the open pore configuration, a very high conversion of pectin and oleuropein is simultaneously obtained (93% and 95%, in 165 h, respectively); whereas, in the closed pore configuration, an increased and exclusive conversion (95% in 24 h) of pectin was obtained. This innovative strategy of artificial ordered compartmentalization allows tuning the enzymatic reactions based on pH, preserving labile biomolecules (e.g.β-glucosidase) from deactivation at acidic pH and cleaning the membrane avoiding aggressive solvents. This makes it possible to increase the stability of enzymes, which is an obstacle to the development of biocatalytic membrane reactors, and proposes an unconventional and efficient way to synchronize the action of complementary enzymes in a case, or to selectively enhance the action of one of them by simply shifting the pH.

Numerical solution-based algorithm assisted development of a continuous flow microwave reactor

Continuous flow microwave heating is a sustainable technology favored in the chemical and food processing sectors due to its short residence time and relatively low environmental footprint. To address the complexity of fluid dynamics and electromagnetic field interactions, nuanced evaluation methods beyond conventional reflection coefficient analysis are necessary to predict its efficiency and uniformity. In this study, a numerical solution-based algorithm is utilized to propose synchrony and cumulative index metrics for performance analysis. Although identical S-parameter systems demonstrate approximate electromagnetic power loss density in the fluid region, significant disparities in heating performance are observed, evidenced by outlet temperatures ranging between 108.10 °C and 147.09 °C, and covariances ranging from 0.07 to 0.46. The power loss density is corrected based on velocity to introduce the synchrony index, which is further calculated into the cumulative index. This approach provides accurate predictions of efficiency and uniformity, informing system designs that align with specific performance objectives. To achieve the best uniformity in simulated two-part systems, a combination of 63 % GIM system and 37 % EBH-2 system in terms of power input was found to be optimal. However, when considering temperature dependent dielectric properties, the optimal combination was adjusted to 60 % GIM system and 40 % EBH-4 system. The numerical solution-based algorithm facilitates optimization of complex continuous flow microwave systems, providing invaluable insights into the time–space electromagnetic response mechanism of fluids.

Superoxide versus peroxide activation of dye decolorizing peroxidases for bioelectrocatalysis

Here we show that dye decolorizing peroxidases can be electrochemically activated for substrate oxidation without addition of exogenous H2O2, yielding activities similar or better than in their conventional operation. The method is based on the in situ generation of O2•−, •OH and H2O2. These species bind the heme to form catalytically competent oxoiron intermediates. Activation of the Pseudomonas putida enzyme is mainly mediated by O2•−, while those from Thermobifida fusca and Saccharomonospora viridis show preferential activation by H2O2. This differential reactivity is explained by the dynamics of a conserved distal aspartate residue. In contrast to previous reports on the Bacillus subtilis enzyme, none of the peroxidases studied here show significant •OH mediated activation, as this radical is quenched by reactive amino acids abundant in these proteins. These results pave the way for the development of bioelectrocatalytic reactors based on dye decolorizing peroxidases for water remediation and biomass processing.

Structured nanoporous Cu/ZnO catalysts for on-board methanol steam reforming prepared by laser powder bed fusion and dealloying

The development of efficient structural catalysts and reactors (SCRs) for on-board methanol steam reforming (MSR) has long been a focal point. Traditional MSR SCRs exhibit problems such as poor heat transfer, low catalyst loading, and coating delamination. In this study, novel three-dimensional graded nanoporous Cu/ZnO (3DNP-Cu/ZnO) SCRs were prepared via metal 3D printing technology and dealloying. For 3DNP-Cu/ZnO SCRs activated with MeOH/H2O steam, both the interfacial area of Cu-ZnO and the Cu+/(Cu0 + Cu+) molar ratio were greater than those of catalysts activated with H2/N2 mixtures. The experimental results showed that a 3DNP-Cu/ZnO SCR activated with MeOH/H2O for 20 min exhibited a high methanol conversion rate of 98.3 % with a CO selectivity of 0.86 % (with a reaction temperature of 280 °C, a water-to-alcohol molar ratio of 1.3 and a weight hourly space velocity of 30 h−1). The superior catalytic activity was attributed to the high Cu+/(Cu++Cu0) ratio, which enabled the generation of *CHOO during the MSR reaction. Additionally, the 3DNP-Cu/ZnO SCRs demonstrated low pressure drops and high mechanical strengths. Computational fluid dynamics simulations showed that the gyroid lattice-structured catalyst achieved a high H2 concentration due to its high mass and heat transfer. 3DNP-Cu/ZnO SCRs provide a new strategy for the preparation of MSR SCRs with broad application prospects.

Development and Exploitation of a New Flow Reactor for Electrophotocatalysis (EPC)

Development and Exploitation of a New Flow Reactor for Electrophotocatalysis (EPC)

Experimental study on charging and discharging characteristics of copper finned metal hydride reactor for stationary hydrogen storage applications

With the shift in power generation methods from conventional to renewable, the need for energy storage has increased, and hydrogen as a carrier has great potential. The storage of hydrogen is one of the main obstacles to the effective deployment of the hydrogen economy. Since metal hydride offers a higher energy density than conventional methods, it can potentially be used to store and deliver hydrogen. Also, the metal hydride hydrogen storage system is the primary element of the energy storage system that connects hydrogen production and consumption. Therefore, the present study is focused on the development and testing of a metal hydride reactor. In the present experimental study, 9 kg of La0.7Ce0.1Ca0.3Ni5 is loaded in a single tube copper finned reactor attached to an external jacket, and the charging and discharging characteristics related to hydrogen storage are analysed along with variations in its thermal performance under various operating conditions. Also, the effect of HTF temperature on the hydrogen release performance of the copper finned reactor is studied under constant discharge pressure and constant discharge flow rate. Further, a comparison has been made between the copper and aluminium finned reactors. This fabricated copper finned reactor attained volumetric and gravimetric storage densities of 21.78 kg per m3 of H2 and 0.77%, respectively. The results indicated that La0.7Ce0.1Ca0.3Ni5 filled within the copper finned reactor stores 1.45 wt.% (130.7 g) of hydrogen in 680 s, corresponding to 25 bar feed gas pressure. At the HTF temperature of 60 °C, the copper-finned reactor discharged 1.42 wt.% (127.3 g) of hydrogen in 1450 s, showing the release of 98% of the stored mass of hydrogen. Further, the developed copper finned MH reactor could supply hydrogen at a constant rate of 13 lpm with a capability of 90% discharge even at a discharge temperature of 30 °C. Beside this, the comparative results showed that adding copper fins showed a considerable improvement over aluminium fins during discharging compared to the charging process. The copper-finned reactor consumed 20.9% and 23.6% less time to release 1 wt.% of hydrogen than the aluminium-finned reactor at discharge temperatures of 40 °C and 50 °C, respectively.

Multiphysics Analysis of PLOFC and DLOFC Accidents in the HTGR-TR

High-temperature, gas-cooled reactors (HTGRs) are promising advanced reactor designs. Leveraging passive safety features, higher core outlet temperatures, previous commercial operational experience, and potential coupling with nonelectrical systems, HTGRs present many advantages over traditional light water reactors and other advanced reactor designs. The High-Temperature, Gas-Cooled Test Reactor (HTGR-TR) is a point design developed by Idaho National Laboratory as a response to the need for the expansion of U.S. test reactor capabilities. The HTGR-TR was designed to serve as a test reactor for Generation-IV small modular prismatic block HTGRs and to provide irradiation data, two crucial contributions to the development of advanced reactors. As in any reactor design, it is necessary to understand the behavior of the reactor during accident scenarios to determine the overall safety of the design. Pressurized loss of forced cooling (PLOFC) and depressurized loss of forced cooling (DLOFC) are two accidents that can occur in HTGRs and that present challenges to decay heat removal. In order to understand the behavior of the fuel during these accidents, the resulting mechanical behavior and fission product migration in the fuel are evaluated. Using the HTGR-TR design, which utilizes tristructural isotropic (TRISO) fuel, a multiphysics analysis during the PLOFC and DLOFC transients was performed. This study utilizes neutronics, thermal hydraulics, and fuel performance modeling to analyze the behavior of TRISO particles during steady-state operation and the described transients. This analysis aims to characterize the hoop stress and strain during the transients, as well as predict fission product migration and radiological release. Due to the startup conditions of the HTGR-TR, the silicon carbide (SiC) layer for both of the transients and steady-state conditions are initially in compression for both the hoop stress and strain. The DLOFC transient at the beginning of cycle was the most challenging overall to the fuel, having the closest to tensile behavior and the closest to tensile strain. Because the integrity of the SiC layer was not challenged during any of the transients, the release of 90Sr and 137Cs was found to be negligible. The PLOFC transient at the end of cycle resulted in the largest 110mAg release and subsequent radioactivity increase. However, the increase in radioactivity was minor when compared to typical operating conditions due to the relatively large diffusivity of 110mAg though SiC at normal operating temperatures. Highlights include Neutronics and thermal-hydraulic modeling generating steady-state and transient conditions for use in fuel performance analysis.2. Detailed BISON analysis demonstrating the excellent performance of TRISO fuel during PLOFC and DLOFC transients.3. Fuel behavior showing negligible fission product release.

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&amp;D) and advancing through test reactors, small and large demonstration reactors, and first commercial-scale units. Following proof-of-principle R&amp;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&amp;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.