Fuel Swelling and Creep Analysis for a MURR LEU U-10Mo Monolithic Plate

U-10Mo monolithic fuel is considered for the conversion of the US High Performance Research and Test Reactors (USHPRR) from high enriched uranium (HEU) to high density low enrichment uranium (LEU) fuel. The monolithic fuel plates are comprised of high density LEU-10Mo fuel core sandwiched between zirconium diffusion barrier interlayers and encapsulated in an aluminum alloy cladding. The conversion of the University of Missouri Research Reactor (MURR), one of the USHPRR fleet, from the use of HEU to LEU is currently in progress. Preliminary safety analysis for the conversion of MURR assumes maximum increase in plate thickness of about 0.1 mm due to irradiation effects. Finite element analysis (FEA) was used to model the thermo-mechanical behavior of a MURR LEU-10Mo monolithic plate under typical irradiation conditions in the LEU core. The maximum increase of the plate thickness was determined considering various combinations of swelling correlations and coefficient of creep rate. Analysis of the displacement profiles showed that maximum displacement along the plate thickness direction occurs at the same location in all cases. For any of the swelling correlations considered in this work, the lowest creep rate coefficient, 5 (× 10−25 cm3/MPa-fission), was found to cause larger outboard displacement. The maximum increase in plate thickness was found not to exceed 0.083 mm with a combination of fuel creep coefficient in the range between 750 and 250 (× 10−25 cm3/MPa-fission) and the the 95% UCL of the most conservative U-10Mo correlation available to describe fuel swelling.

Hydrodynamic Response of the Deep Turbine Installation-Floating Concept

Floating offshore wind turbine (FOWT) installations are progressing from the R&D stage to commercial installation projects. The prospective sites are situated in increasingly deeper water and further away from the shore. This paper presents the Deep Turbine Installation-Floating (DTI-F) concept, an innovative hybrid spar buoy-based FOWT capable of being able to raise and lower the tower and nacelle, which simplifies construction, installation, maintenance and decommissioning. The study is focused on the hydrodynamics of the moored floating system, and it is based on experimental and numerical modelling work. A 1:45 Froude scaled model of the DTI-F wind concept was tested using three different mooring configurations: i) three mooring lines, ii) four mooring lines, and iii) three mooring lines with a delta connection. Free decay and stiffness decay tests were carried out together with regular and irregular wave tests. The numerical study comprises diffraction (ANSYS AQWA) and time-domain modelling (OrcaFlex). The experimental hydrostatic and hydrodynamic results are compared with the numerical simulations based on the as-built scale model. Considering the natural frequencies results obtained for the three mooring configurations, the three lines configuration without delta connection was selected as the most suitable design. The obtained results for the three mooring lines configuration show good agreement between the experiment and numerical simulations. The presented analysis of the design concept indicates a high degree of technical feasibility.

Study on Heat Storage Change Characteristics of a Double Reheat Boiler During Load Cycling Processes

The stability of the live and reheat steam temperatures is of great significance for the efficient, flexible and safe operation of coal-fired power plants. The double reheat boilers are large inertia, non-linearity and high coupling. Therefore, the temperature controls of live and reheat steams are very difficult during load cycling processes. The heat storage in the double reheat boiler changes during load cycling process, which will affect the performances of temperature control. In this study, dynamic simulation models of an ultra-supercritical double reheat tower boiler and its temperature control models are developed based on the GSE software. These models are validated. Then, changes of the boiler system heat storage during different load cycling processes are studied. Results reveal that the metal heat storage is more than working medium ones at steady state load. However, the changing quantities of working medium heat storage are more than the metal ones between different loads. During load cycling processes, the changing tendencies of reheat steam temperatures, the difference of heat storage between real-time and steady state values (DHSBRS) and the difference of coal feeding rate between real-time and steady values (DCBRS) are similar. The fluctuations of reheat steam temperatures have a delay compared with DHSBRS ones, and the fluctuations of DHSBRS fluctuation have a delay compared with DCBRS ones. The delay time increases with the load cycling rates. The results are aimed at providing some guidance for the control system design of the double-reheat boiler system and the safe and flexible operation of power plants.

Smart Sensor Technologies for Performance Optimization of Power Generating Assets

Significant research is ongoing on several fronts in smart sensor technologies for optimizing the performance of power generating assets. The initiatives include: 1. Real-time models with advanced computational algorithms, embedded intelligence at sensor and component level for reducing operating costs, improving efficiencies, and lowering emissions. 2. Optical sapphire sensors for monitoring operation and performance of critical components in harsh environments, for improving accuracy of measurements in combustion monitoring, and lowering operating costs. 3. Wireless technologies using (a) microwave acoustic sensors for real-time monitoring of equipment in high temperature/pressure environments (b) integrated gas/temperature acoustic sensors for combustion monitoring in diverse harsh environment locations to improve combustion efficiency, reduce emissions, and lower maintenance costs (c) sensors for sensing temperature, strain and soot accumulation inside coal-fired boilers for detailed condition monitoring, better understanding of combustion and heat exchange processes, improved designs, more efficient operation. 4. Distributed optical fiber sensing system for real-time monitoring and optimization of high temperature profiles for improving efficiency and lowering emissions. 5. Smart parts with embedded sensors for in situ monitoring of multiple parameters in existing and new facilities. 6. Optimizing advanced 3D manufacturing processes for embedded sensors in components for harsh environments to reduce costs and improve efficiency of power generation facilities with carbon capture capabilities. 7. New energy-harvesting materials for powering wireless sensors in harsh environments, improving reliability of wireless sensors in demanding environments, and in-situ monitoring and performance of devices and systems. 8. Real-time, accurate and reliable monitoring of temperature at distributed locations of sensors in harsh environments for improving operations and reducing operating costs. 9. Algorithms and methodologies for designing control systems utilizing distributed intelligence for optimal control of power generation facilities. 10. Gas sensors for monitoring high temperatures in harsh environments for lowering operating costs and better control of operations. 11. Optimizing placement of smart sensors in networks for cognitive behavior and self-learning. This paper provides an overview of the initiatives in smart sensor technologies and their applications in optimizing the performance of power generating facilities.

Effect of Zr Diffusion Barrier Properties on the Irradiation Performance of U-10Mo Monolithic Fuel Plate

The most recent design of U-Mo monolithic fuel as adopted by the U.S. for the conversion of its High Performance Research Reactors (USHPRR) from high enrichment uranium (HEU) to low enrichment uranium fuel (LEU, < 20% U235) consists of a high density (LEU) U-10Mo fuel sandwiched between Zirconium (Zr) diffusion barriers and encapsulated in aluminum (AA6061) cladding. In this work, finite element analysis (FEA) was used to evaluate effect of Zr diffusion barrier properties on the thermal and mechanical performance of a U-10Mo monolithic fuel plate by considering possible variation in thermal and mechanical properties of the Zr diffusion barrier. Possible variation in thermo-mechanical properties of the Zr diffusion barrier were determined and a simulation matrix was designed accordingly. Analyses of simulation results included determination of global peak stresses in the fuel, Zr diffusion barrier, and cladding sections as well as the plate thickness profile at a transverse section toward the top side of the plate. Results showed that variation in yield stress, elastic modulus and thermal conductivity of the Zr diffusion barrier has negligible effect on the thermal and mechanical performance of the monolithic fuel plate. The effect of variation in these properties was found to be limited to the barrier section itself, which may be attributed to the relatively smaller thickness of that section compared to the fuel and cladding sections of the fuel plate.

Dynamic Simulation Study on a Coal-Fired Power Plant Aided With Low-Temperature Solar Energy

The concept of coal-fired power generation aided with solar energy uses stable fossil energy to compensate the instability and intermittently of solar power and reduces the cost of concentrated solar power (CSP) by decreasing the large-scale heat storage and turbine systems of CSP. In this study, trough solar collector system (TSCS) was integrated into the low-pressure heater side of a 660 MW coal-fired power generation system. In the system in which the 6# LP heater is completely replaced by TSCS, the variation value of the steam extraction flowrate of the LP heaters and the turbine output power decrease with the reduction in loads from 100% to 60% THA, and the output power increases by approximately 1 MW under 100% THA. When TSCS completely replaces the 6# LP heater under the load of 75%, the effects of direct normal irradiance (DNI) increase and flow ratio decrease on the main operating parameters of solar-aided coal-fired power plant (SCPP) were studied. Results show that the step increase of DNI decreases the 5# steam extraction flowrate and increases the output power by nearly 3 MW. When the flow ratio decreases by 139.87 kg/s, the output power decreases by around 0.35 MW. The dynamic characteristics of SCPP under different parallel situations with the load of 75% were also studied. As the number of parallel stage increases, the decrement in 5# steam extraction flowrate and the increment in output power decrease. The response time also decreases. Our study aims to provide detailed references for the control system design and optimization of coal-fired power units aided with solar energy.

Powder-Binder Jetting Large-Scale, Metal Direct-Drive Generators: Selecting the Powder, Binder, and Process Parameters

Additive manufacturing enables the production of complex geometries extremely difficult to create with conventional subtractive methods. While good at producing complex parts, its limitations can be seen through its penetration into everyday manufacturing markets. Throughput limitations, poor surface roughness, limited material selection, and repeatability concerns hinder additive manufacturing from revolutionizing all but the low-volume, high-value markets. This work characterizes combining powder-binder jetting with traditional casting techniques to create large, complex metal parts. Specifically, we extend this technology to wind turbine generators and provide initial feasibility of producing complex direct-drive generator rotor and stator designs. In this process, thermal inkjet printer heads selectively deposit binder on hydroperm casting powder. This powder is selectively solidified and baked to remove moisture before being cast through traditional methods. This work identifies a scalable manufacturing process to print large-scale wind turbine direct drive generators. As direct-drive generators are substantially larger than their synchronous counterparts, a printing process must be able to be scaled for a 2–5 MW 2–6m machine. For this study, research on the powder, binder, and printing parameters is conducted and evaluated for scalability.

Pyrolysis and CO2 Gasification of Composite Polymer Absorbent Waste for Syngas Production

Development of alternative carbonaceous sources for energy production is essential to alleviate the dependence on depleting fossil fuels which led to increasing atmospheric CO2 and thus global warming. While biomass utilization for energy and chemical production has been extensively studied in the literature, such studies on municipal solid wastes is difficult to interpret due to the heterogeneous nature of the waste. Understanding of the influence of individual components is necessary for comprehensive development of waste-to-energy pathway. One such waste that is complicated and has often been ignored in the literature is composite polymer absorbent material waste which can also be considered as a potential feedstock for thermochemical pathway of energy production. Composite polymer absorbent materials are ubiquitously used these days in the form of sanitary napkins, diapers, water blockers, fire blockers and surgical pads due to their high water-absorptive nature. Pyrolysis and CO2 gasification is ideal for such materials due to its versatile feedstock intake and uniform product output in the form of syngas with adjustable composition. CO2 gasification also provides the added benefit of CO2 utilization which provides carbon offset to this process. In the present study, a mixture of cellulose, absorbent material (sodium polyacrylate), polypropylene and polystyrene in a fixed proportion, to model approximate composition of a diaper, was examined for its pyrolysis and CO2 gasification capability for viable syngas production. The influence of individual components into the syngas yield from the composite waste gasification was also investigated. A fixed-bed, semi-batch reactor facility along with gas chromatography was employed to analyse the syngas yield and compositional evolution. Pyrolysis was done under nitrogen atmosphere and gasification was done under CO2 atmosphere. CO2 gasification provided net CO2 consumption which means a net reduction in carbon emissions per joule of energy produced. The sample was tested under four isothermal conditions of 973, 1073, and 1173 K to understand the impact of operational conditions on the syngas yield. Influence of individual component of the composite absorbent waste on the syngas yield and composition was also analyzed by comparing these syngas characteristics with that of the yield from gasification of its individual components separately at 1173 K. These investigations provided us with novel results on the behavior and capabilities of these composite polymer absorbent wastes and which opens up a new avenue towards efficient utilization of solid waste resources for sustainable energy production in the form of syngas which can also be used for various chemicals production such as methanol, gasoline and other petrochemical products.

Integration of Flame-Assisted Fuel Cells With a Gas Turbine Running Jet-A As Fuel

In recent years, the aircraft industry is heading towards the concept of the More Electric Airplane (MEA). Previous research has investigated the possibility of integrating Dual Chamber Solid Oxide Fuel Cells (DC-SOFC) with the auxiliary power unit (APU) of the aircraft. This paper evaluates the merits of integrating the recently proposed Flame-assisted Fuel Cells (FFCs) with the APU gas turbine system. The syngas composition for fuel-rich combustion is studied using chemical equilibrium analysis of Jet-A/air at 8 Bar and 1073 K. The results show the potential for reforming Jet-A fuel to 22% Carbon Monoxide and 18% Hydrogen in the exhaust at an equivalence ratio of 2.4. The paper also reports how the efficiency of power generation changes when FFCs are placed in the combustor of a turbine in the APU. The maximum theoretical electrical efficiency of the FFC/combustor and the area and weight of the fuel cell required to generate the design power is calculated. The FFC offers a viable substitute for the DC-SOFC to be integrated with the APU.

Cylindrical Parabolic Trough Concentrator and Solar Tower Comparison in an Integrated Solar Combined Cycle Power Plant

The intermittency of renewable energies continues to be a limitation for their more widespread application because their large-scale storage is not yet practical. Concentrating solar power (CSP) has the possibility of thermally storing this energy to be used in times of higher demand at a more feasible storage price. The number of concentrated solar energy related projects have grown rapidly in recent years due to the advances in the associated solar technology. Some of the remaining issues regarding the associated high investment costs can be solved by integrating the solar potential into fossil fuel generation plants. An integrated solar combined cycle system (ISCCS) tends to be less dependent to climatic conditions and needs less capital inversion than a CSP system, letting the plant be more reliable and more economically feasible. In this work thus, two technologies of solar concentration (i) parabolic trough cylinder (PTC) and (ii) solar tower (ST) are initially integrated into a three-pressure levels combined cycle power plant. The proposed models are then modeled, simulated and properly assessed. Design and off design point computations are carried out taking into account local environmental conditions such as ambient temperature and direct solar radiation (DNI). The 8760 hourly-basis simulations carried out allow comparing the thermal and economic performance of the different power plant configurations accounted for in this work. The results show that injecting energy into the cycle at high temperatures does not necessarily imply a high power plant performance. In the studied plant configurations, introducing the solar generated steam mass flow rate at the evaporator outlet is slightly more efficient than introducing it at cycle points where temperatures are higher. At design point conditions thus, the plant configuration where the referred steam mass flow rate is introduced at the evaporator outlet generates 0.42% more power than those in which the steam is injected at higher cycle temperatures. At off design point conditions this value is reduced to 0.37%. The results also show that the months with high DNI values and those with low mean ambient temperatures are not necessarily the months which lead to the highest power outputs. In fact a balance between these two parameters, DNI and ambient temperature, leads to an operating condition where the power output is the highest. All plant configurations analyzed here are economically feasible, even so PTC related technologies tend to be more economically feasible than ST ones due to their lower investment costs.