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At least 739 records · Page 41

NREL Pyrheliometer Comparison: September 16 to 27, 2013 (NPC-2013)

Accurate measurements of direct normal (beam) solar irradiance from pyrheliometers are important for the development and deployment of solar energy conversion systems, improving our understanding of the Earth's energy budget for climate change studies, and for other science and technology applications involving solar flux. Providing these measurements places many demands on the quality system used by the operator of commercially available radiometers. Maintaining accurate radiometer calibrations traceable to an international standard is the first step in producing research-quality solar irradiance measurements. As with all measurement systems, absolute cavity radiometers and other types of pyrheliometers are subject to performance changes over time. NREL has developed and maintained a group of absolute cavity radiometers with direct calibration traceability to the World Radiometric Reference (WRR). These reference instruments are used by NREL to calibrate pyrheliometers and pyranometers using the ISO 17025 accredited Broadband Outdoor Radiometer Calibration (BORCAL) process (Reda et al. 2008). NPCs are held annually at the Solar Radiation Research Laboratory (SRRL) in Golden, Colorado. Open to all pyrheliometer owners/operators, e.g. NREL, NASA, NIST, NOAA, USA industry and academia, USA-DOE and other national laboratories, and national and international organizations. Each NPC provides an opportunity to determine the unique World Radiometric Reference (WRR) transfer factor (WRR-TF) for each participating pyrheliometer. By adjusting all subsequent pyrheliometer measurements by the appropriate WRR-TF, the solar irradiance data are traceable to the International System of Units through WRR.

14 SOLAR ENERGY↗

Process/Equipment Co-Simulation on Syngas Chemical Looping Process

The chemical looping strategy for fossil energy applications promises to achieve an efficient energy conversion system for electricity, liquid fuels, hydrogen and/or chemicals generation, while economically separate CO 2 by looping reaction design in the process. Chemical looping particle performance, looping reactor engineering, and process design and applications are the key drivers to the success of chemical looping process development. In order to better understand and further scale up the chemical looping process, issues such as cost, time, measurement, safety, and other uncertainties need to be examined. To address these uncertainties, advanced reaction/reactor modeling and process simulation are highly desired and the modeling efforts can accelerate the chemical looping technology development, reduce the pilot-scale facility design time and operating campaigns, as well as reduce the cost and technical risks. The purpose of this work is thus to conduct multiscale modeling and simulations on the key aspects of chemical looping technology, including particle reaction kinetics, reactor design and operation, and process synthesis and optimization.

42 ENGINEERING↗

Development of a Smart MicroGrid Testbed

Demand for electricity is rapidly increasing thereby applying pressure to expand generation and distribution capacity worldwide. The expansion of traditional services not only imposes burdens on financial resources but also encounters many challenges from community residents who oppose the construction of new power generation plants or transmission facilities in their backyard. From the integrated resource planning point of view, a feasible and economical remedy is, therefore, to utilize existing dispersed generation capacity known as distributed generation (DG) and/or renewable energy resources that may exist in the vicinity of the load centers. The main criteria for selecting the type of fuel source for a DG is its local availability, conversion system technological advancement, impact on the environment, and operating cost. DG’s have existed in the market for many years. Large diesel or gas powered generation sets are used in stand-by mode to power up vital services such as hospitals, financial and commercial compounds, telecommunication centers and industrial premises. Wind turbines, photovoltaic energy sources, and fuel cells are new comers that are now competing in size and efficiency with many standard generating sets. With this in mind, they are being used in many places not only as stand-by units but as the prime source of power particularly when the $\$$/kWhr rate is high.

24 POWER TRANSMISSION AND DISTRIBUTION↗

NREL Pyrheliometer Comparisons: September 22-26, 2014 (NPC-2014)

Accurate measurements of direct normal (beam) solar irradiance from pyrheliometers are important for developing and deploying solar energy conversion systems, improving our understanding of the Earth's energy budget for climate change studies, and for other science and technology applications involving solar flux. Providing these measurements places many demands on the quality system used by the operator of commercially available radiometers. Maintaining accurate radiometer calibrations that are traceable to an international standard is the first step in producing research-quality solar irradiance measurements. As with all measurement systems, absolute cavity radiometers and other types of pyrheliometers are subject to performance changes over time. NREL has developed and maintained a select group of absolute cavity radiometers with direct calibration traceability to the World Radiometric Reference (WRR), and uses these reference instruments to calibrate pyrheliometers and pyranometers using the ISO 17025 accredited Broadband Outdoor Radiometer Calibration (BORCAL) process. National Renewable Energy Laboratory (NREL) pyrheliometer comparisons (NPCs) are held annually at the Solar Radiation Research Laboratory (SRRL) in Golden, Colorado. Open to all pyrheliometer owners and operators, each NPC provides an opportunity to determine the unique WRR transfer factor (WRR-TF) for each participating pyrheliometer. By adjusting all subsequent pyrheliometer measurements by the appropriate WRR-TF, the solar irradiance data are traceable to the WRR. NPC-2014 was held September 22-26, 2014. Participants operated 36 absolute cavity radiometers and 22 conventional thermopile-based pyrheliometers to simultaneously measure clear-sky direct normal solar irradiance during this period, and this report documents the findings.

14 SOLAR ENERGY↗

FY 2014 Sodium-Supercritical CO 2 Interactions in the SNAKE Experiment Facility

One appealing feature of the supercritical carbon dioxide Brayton cycle energy conversion system is the small footprint that the hardware requires, which is in part due to the use of compact diffusion-bonded heat exchangers such as Printed Circuit Heat Exchanger (PCHEs) or Hybrid Heat Exchangers (H 2 X) as the heat source heat exchanger (sodium-to-CO 2 ) as well as the recuperator and cooler modules. Although PCHEs and H 2 Xs have a high degree of structural integrity, the potential for leaks to develop between the sodium and CO 2 coolant channels in the heat exchanger cannot be ruled out, and this would lead to discharge of high pressure CO 2 into the secondary coolant circuit. Due to the robustness of the PCHE design, catastrophic failure leading to CO 2 jet blowdown into the secondary sodium loop is not deemed likely. Rather, small cracks (or micro-leaks) may develop in which CO 2 will bleed into the secondary system at a relatively low rate and chemically react with the sodium. The goal of the sodium-CO 2 interaction tests is to gain a fundamental understanding of sodium-CO 2 interactions under prototypical conditions of compact diffusion-bonded heat exchanger failure, a fundamental understanding of self-plugging if it occurs, and the development of one-dimensional phenomenological models for the interactions between high-pressure CO 2 issuing into liquid sodium from a micro-leak across a stainless steel pressure boundary. These models will be validated using experiment data. Therefore, an experiment program at Argonne was initiated in Fiscal Year 2010 to investigate the reaction behavior between sodium and CO 2 under micro-leak conditions. Several reports have described the facility scaling rationale and design. Assembly of the SNAKE (S-CO 2 , Na Kinetics Experiment) began in Fiscal Year 2011 and was completed in July 2012. The sodium inventory in this facility consists of approximately 44 lbs (20 kg; ~21 L/5.5 gal).

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Description of the First Observed Sodium-C0 2 Reactions in the Sodium CO 2 Interaction Experiment (SNAKE)

One appealing feature of the supercritical carbon dioxide Brayton cycle energy conversion system is the small footprint that the hardware requires, which is in part due to the use of Printed Circuit Heat Exchangers (PCHEs) as the heat source heat exchanger (sodium-to-CO 2 ) as well as the recuperator and cooler modules. Although PCHEs have a high degree of structural integrity, the potential for leaks to develop between the sodium and CO 2 coolant channels in the secondary heat exchanger cannot be ruled out, and this would lead to discharge of high pressure CO 2 into the secondary coolant circuit. Due to the robustness of the PCHE design, catastrophic failure leading to CO 2 jet blowdown into the secondary sodium loop is not deemed likely. Rather, small cracks (or micro-leaks) may develop in which CO 2 will bleed into the secondary system at a relatively low rate and chemically react with the sodium. The goal of the sodium-CO 2 interaction tests is to gain a fundamental understanding of sodium-CO 2 interactions under prototypical conditions of compact diffusion-bonded heat exchanger failure, a fundamental understanding of self-plugging if it occurs, and the development of one-dimensional phenomenological models for the interactions between high-pressure CO 2 issuing into liquid sodium from a micro-leak across a stainless steel pressure boundary. These models will be validated using experiment data. Therefore, an experiment program at Argonne was initiated in Fiscal Year 2010 to investigate the reaction characteristics between sodium and CO 2 under micro-leak conditions. Several reports have described the facility scaling rationale and design. Assembly of the SNAKE (S-CO 2 , Na Kinetics Experiment) began in Fiscal Year 2011 and was completed in July 2012. Approximately 44 lbs (20 kg; ~21 L/5.5 gal) of sodium was transferred into the SNAKE dump tank from a drum of clean sodium in July 2012.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Conjugated ionomers for photovoltaic applications: electric field driven charge separation in organic photovoltaics (Final Technical Report)

The central goal of the work we completed was been to understand the photochemical and photovoltaic properties of ionically functionalized conjugated polymers (conjugated ionomers or polyelectrolytes) and energy conversion systems based on them. We primarily studied two classes of conjugated polymer interfaces that we developed based either upon undoped conjugated polymers with an asymmetry in ionic composition (the ionic junction) or doped conjugated polymers with an asymmetry in doping type (the p-n junction). The materials used for these studies have primarily been the polyacetylene ionomers. We completed a detailed study of p-n junctions with systematically varying dopant density, photochemical creation of doped junctions, and experimental and theoretical work on charge transport and injection in polyacetylene ionomers. We have also completed related work on the use of conjugated ionomers as interlayers that improve the efficiency or organic photovoltaic systems and studied several important aspects of the chemistry of ionically functionalized semiconductors, including mechanisms of so-called "anion-doping", the formation of charge transfer complexes with oxygen, and the synthesis of new polyfluorene polyelectrolytes. We also worked worked with the Haley group at the University of Oregon on new indenofluorene-based organic acceptors.

14 SOLAR ENERGY↗

FASTER test reactor preconceptual design report summary

The FASTER reactor plant is a sodium-cooled fast spectrum test reactor that provides high levels of fast and thermal neutron flux for scientific research and development. The 120MWe FASTER reactor plant has a superheated steam power conversion system which provides electrical power to a local grid allowing for recovery of operating costs for the reactor plant.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

NREL Pyrheliometer Comparisons: September 26-October 7, 2016 (NPC-2016)

Accurate measurements of direct normal (beam) solar irradiance from pyrheliometers are important for developing and deploying solar energy conversion systems, improving our understanding of the Earth's energy budget for climate change studies, and for other science and technology applications involving solar flux. Providing these measurements places many demands on the quality system used by the operator of commercially available radiometers. Maintaining accurate radiometer calibrations that are traceable to an international standard is the first step in producing research-quality solar irradiance measurements. National Renewable Energy Laboratory (NREL) pyrheliometer comparisons (NPCs) are held annually at the Solar Radiation Research Laboratory (SRRL) in Golden, Colorado. Open to all pyrheliometer owners and operators, each NPC provides an opportunity to determine the unique World Radiometric Reference transfer factor (WRR-TF) for each participating pyrheliometer. By adjusting all subsequent pyrheliometer measurements by the appropriate WRR-TF, the solar irradiance data are traceable to the WRR. NPC-2016 was September 26 through October 7, 2016. Participants operated 45 absolute cavity radiometers and 27 conventional thermopile-based pyrheliometers to simultaneously measure clear-sky, direct normal solar irradiance during this period.

14 SOLAR ENERGY↗

FASTER Test Reactor Preconceptual Design Report

The FASTER test reactor plant is a sodium-cooled fast spectrum test reactor that provides high levels of fast and thermal neutron flux for scientific research and development. The 120MWe FASTER reactor plant has a superheated steam power conversion system which provides electrical power to a local grid allowing for recovery of operating costs for the reactor plant.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Corrosion of Structural Materials for Advanced Supercritical Carbon- Dioxide Brayton Cycle

The supercritical carbon-dioxide (referred to as SC-CO 2 hereon) Brayton cycle is being considered for power conversion systems for a number of nuclear reactor concepts, including the sodium fast reactor (SFR), fluoride saltcooled high temperature reactor (FHR), and high temperature gas reactor (HTGR), and several types of small modular reactors (SMR). The SC-CO 2 direct cycle gas fast reactor has also been recently proposed. The SC-CO 2 Brayton cycle (discussed in Chapter 1) provides higher efficiencies compared to the Rankine steam cycle due to less compression work stemming from higher SC-CO 2 densities, and allows for smaller components size, fewer components, and simpler cycle layout. For example, in the case of a SFR using a SC-CO 2 Brayton cycle instead of a steam cycle would also eliminate the possibility of sodium-water interactions. The SC-CO 2 cycle has a higher efficiency than the helium Brayton cycle, with the additional advantage of being able to operate at lower temperatures and higher pressures. In general, the SC-CO 2 Brayton cycle is well-suited for any type of nuclear reactor (including SMR) with core outlet temperature above ~ 500°C in either direct or indirect versions. In all the above applications, materials corrosion in high temperature SC-CO 2 is an important consideration, given their expected lifetimes of 20 years or longer. Our discussions with National Laboratories and private industry early on in this project indicated materials corrosion to be one of the significant gaps in the implementation of SC-CO 2 Brayton cycle. Corrosion can lead to a loss of effective load-bearing wall thickness of a component and can potentially lead to the generation of oxide particulate debris which can lead to three-body wear in turbomachinery components. Another environmental degradation effect that is rather unique to CO 2 environment is the possibility for simultaneous occurrence of carburization during oxidation of the material. Carburization can potentially lead to embrittlement of structural alloys in SC-CO 2 Brayton cycle. An important consideration in regards to corrosion is that the temperatures can vary widely across the various sections of the SC-CO 2 Brayton cycle, from room temperature to 750°C, with even higher temperatures being desirable for higher efficiencies. Thus the extent of corrosion and corrosion mechanisms in various components and SC-CO 2 Brayton cycle will be different, requiring a judicious selection of materials for different sections of the cycle. The goal of this project was to address materials corrosion-related challenges, identify appropriate materials, and advance the body of scientific knowledge in the area of high temperature SC-CO 2 corrosion. The focus was on corrosion of materials in SC-CO 2 environment in the temperature range of 450°C to 750°C at a pressure of 2900 psi for exposure duration for up to 1000 hours. The Table below lists the materials tested in the project. The materials were selected based on their high temperature strength, their code certification status, commercial availabilities, and their prior or current usage in the nuclear reactor industry. Additionally, pure Fe, Fe-12%Cr, and Ni-22%Cr were investigated as simple model materials to more clearly understand corrosion mechanisms. This first phase of the project involved testing in research grade SC-CO 2 (99.999% purity). Specially designed autoclaves with high fidelity temperature, pressure, and flow control capabilities were built or modified for this project.

36 MATERIALS SCIENCE↗

Fractional Multistage Hydrothermal Liquefaction of Biomass and Catalytic Conversion into Hydrocarbons

The objective of this project was to develop an improved multistage process for the hydrothermal liquefaction (HTL) of biomass to serve as a new front-end, deconstruction process ideally suited to feed Virent’s well-proven catalytic technology, which is already being scaled up. This process produced water soluble, partially de-oxygenated intermediates that are ideally suited for catalytic finishing to fungible distillate hydrocarbons. Through this project, Virent, with its partners, demonstrated the conversion of pine wood chips to drop-in hydrocarbon distillate fuels using a multi-stage fractional conversion system that is integrated with Virent’s BioForming® process. The majority of work was in the liquefaction task and included temperature scoping, solvent optimization, and separations.

09 BIOMASS FUELS↗

NREL Pyrheliometer Comparisons: September 25-October 6, 2017 (NPC-2017)

Accurate measurements of direct normal (beam) solar irradiance from pyrheliometers are important for developing and deploying solar energy conversion systems, improving our understanding of the Earth's energy budget for climate change studies, and for other science and technology applications involving solar flux. Providing these measurements places many demands on the quality system used by the operator of commercially available radiometers. Maintaining accurate radiometer calibrations that are traceable to an international standard is the first step in producing research-quality solar irradiance measurements. In 1977, the World Meteorological Organization (WMO) established the World Radiometric Reference (WRR) as the international standard for the measurement of direct normal solar irradiance (Frohlich 1991). The WRR is an internationally recognized, detector-based measurement standard determined by the collective performance of six electrically self-calibrated absolute cavity radiometers comprising the World Standard Group (WSG). Various countries, including the United States, have contributed these specialized radiometers to the Physikalisch-Meteorologisches Observatorium Davos - World Radiation Center (PMOD/WRC) to establish the WSG. As with all measurement systems, Absolute Cavity Radiometers (ASR) are subject to performance changes over time. Therefore, every five years the PMOD/WRC in Davos, Switzerland, hosts an International Pyrheliometer Comparison (IPC) for transferring the WRR to participating radiometers. NREL has represented the U.S. Department of Energy (DOE) in each IPC since 1980. As a result, NREL has developed and maintained a select group of absolute cavity radiometers with direct calibration traceability to the WRR, and uses these reference instruments to calibrate pyrheliometers and pyranometers using the International Organization for Standardization (ISO) 17025 accredited Broadband Outdoor Radiometer Calibration (BORCAL) process (Reda et al. 2008). National Renewable Energy Laboratory (NREL) pyrheliometer comparisons (NPCs) are held annually at the Solar Radiation Research Laboratory (SRRL) in Golden, Colorado. Open to all ACR owners and operators, each NPC provides an opportunity to determine the unique WRR transfer factor (WRR-TF) for each participating pyrheliometer. By adjusting all subsequent pyrheliometer measurements by the appropriate WRR-TF, the solar irradiance data are traceable to the WRR.

14 SOLAR ENERGY↗

NREL Pyrheliometer Comparisons: September 24 - October 5, 2018 (NPC-2018)

Accurate measurements of direct normal (beam) solar irradiance from pyrheliometers are important for developing and deploying solar energy conversion systems, improving our understanding of the Earth's energy budget for climate change studies, and for other science and technology applications involving solar flux. Providing these measurements places many demands on the quality system used by the operator of commercially available radiometers. Maintaining accurate radiometer calibrations that are traceable to an international standard is the first step in producing research-quality solar irradiance measurements. In 1977, the World Meteorological Organization (WMO) established the World Radiometric Reference (WRR) as the international standard for the measurement of direct normal solar irradiance (Frohlich 1991). The WRR is an internationally recognized, detector-based measurement standard determined by the collective performance of six electrically self-calibrated absolute cavity radiometers comprising the World Standard Group (WSG). Various countries, including the United States, have contributed these specialized radiometers to the Physikalisch-Meteorologisches Observatorium Davos - World Radiation Center (PMOD/WRC) to establish the WSG. As with all measurement systems, Absolute Cavity Radiometers (ASR) are subject to performance changes over time. Therefore, PMOD/WRC in Davos, Switzerland, hosts an International Pyrheliometer Comparison (IPC) for transferring the WRR to participating radiometers quinquennialy by invitation. NREL has represented the U.S. Department of Energy (DOE) in each IPC since 1980. As a result, NREL has developed and maintained a select group of absolute cavity radiometers with direct calibration traceability to the WRR, and uses these reference instruments to calibrate pyrheliometers and pyranometers using the International Organization for Standardization (ISO) 17025 accredited Broadband Outdoor Radiometer Calibration (BORCAL) process (Reda et al. 2008). To fill the gap between each IPC, NREL pyrheliometer comparisons (NPCs) are held annually at the Solar Radiation Research Laboratory (SRRL) in Golden, Colorado. Open to all ACR owners and operators, each NPC provides an opportunity to determine the unique WRR transfer factor (WRR-TF) for each participating pyrheliometer. By adjusting all subsequent pyrheliometer measurements by the appropriate WRR-TF, the solar irradiance data are traceable to the WRR. NPC-2018 was September 24 through October 5, 2018. Participants operated 43 ACRs to simultaneously measure clear-sky direct normal solar irradiance during this period. The Transfer Standard Group (TSG) of reference radiometers for NPC-2018 consisted of four NREL radiometers with direct traceability to the WRR, having participated in the Twelfth International Pyrheliometer Comparisons (IPC-XII) in the fall of 2015. As a result of NPC-2018, each participating absolute cavity radiometer was assigned a new WRR-TF, computed as the reference irradiance determined by the TSG divided by the observed irradiance from the participating radiometer. The performance of the TSG during NPC-2018 was consistent with previous comparisons, including IPC-XII. The measurement performance of the TSG allowed the transfer of the WRR to each participating radiometer with an estimated uncertainty of plus/minus 0.36% with respect to the International System of Units.

14 SOLAR ENERGY↗

Fiscal Year 2018 Sodium-CO2 Interaction Test

An experiment campaign was continued in Fiscal Year 2018 in the Argonne National Laboratory (Argonne) SNAKE facility that investigated the interactions between supercritical carbon dioxide (sCO 2 ) and sodium through injection of sCO 2 into an open surface sodium pool. Two of fifteen previous SNAKE tests revealed that self-plugging of the leakage path/nozzle occurs at higher initial sodium temperatures of about 500 ºC due to chemical reactions involving CO 2 , sodium, and sodium-CO 2 reaction products. At lower sodium temperatures, the interaction phenomena involve consumption of injected CO 2 and formation of an agglomerated mass of reaction products without self-plugging. The FY 2018 test investigated interactions at an intermediate initial sodium temperature of about 411 ºC, representative of the interior of a sodium-to-CO 2 heat exchanger in a Sodium-Cooled Fast Reactor (SFR) sCO 2 Brayton Cycle energy conversion system. The experiment was successfully conducted and did not show self-plugging as evidenced by a sustained chemical reaction between the injected CO 2 and sodium and consumption of CO 2 .

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Light Material Interactions in Energy Conversion (Final Report)

The scientific vision of the “Light-Material Interactions in Energy Conversion” Energy Frontier Research Center (LMI-EFRC) is embodied in our mission statement: ‘to tailor the morphology, complex dielectric structure, and electronic properties of matter so as to sculpt the flow of sunlight and heat, enabling light conversion to electrical energy with unprecedented efficiency’. Founded in 2009, the LMI-EFRC has become a national resource for fundamental optical principles and phenomena relevant to solar energy conversion, addressing new scientific opportunities that enable efficient utilization of the entire visible and infrared solar resource. The LMI-EFRC is directed by Prof. Ralph Nuzzo and centered at its lead institution, the California Institute of Technology. The Center is an integrated and collaborative partnership of research leaders in photonics and photonic materials, comprising 14 faculty investigators that span six academic departments at five institutions, including Profs. Harry Atwater, Andrei Faraon, Nathan Lewis, and Austin Minnich at Caltech; Profs. Ralph Nuzzo, Paul Braun and John Rogers at the University of Illinois at Urbana-Champaign; Prof. Jennifer Lewis at Harvard University; Profs. Mark Brongersma, Jennifer Dionne, and Shanhui Fan at Stanford University; and Profs. Paul Alivisatos, Eli Yablonovitch, and Xiang Zhang at Lawrence Berkeley National Laboratory. The Center is organized into four research groups (RGs) that address scientific themes related to light-matter interactions, with each team spanning multiple institutional partners and designed to meet our scientific objectives. Notable project outcomes that address the LMI Mission and 2014-2018 goals include: (1) RG1 “New Light Management Mechanisms” demonstrated tunable and active nanostructured patterned surfaces (‘metasurfaces’) for control of light absorption, reflection, and propagation. (2) RG2 “Solar Spectrum Control and Conversion” developed colloidal nanocrystals with designer optical properties for fundamental studies of solar spectrum control and conversion. (3) RG3 “Thermal Photon Harvesting” established photonic design principles to harness and control thermal photons in novel conversion systems. (4) RG4 “Programmable Assembly of Photonic and Electronic Architectures” developed powerful new methods for light- and matter-based additive fabrication of electronic and photonic architectures.

14 SOLAR ENERGY↗

Degradation Mechanisms and Development of Protective Coatings for Thermal Energy Storage and High Temperature Fluid Containment Materials

This research addresses cost savings to achieve the SETO target of $15/kWh th for thermal energy storage and 6¢/kWh for levelized cost of energy. Next-generation solar power conversion systems require high-temperature, advanced fluids in the range of 600° to 900°C. The three major advanced fluid groups—supercritical CO 2 , liquid metal alloys, and molten salts—are very corrosive to common alloys used in vessels, heat exchangers, and piping at these temperatures. Understanding degradation mechanisms is essential for making recommendations on proper working conditions and suitable cost-effective coating materials for CSP applications at high temperatures. The implementation of the findings from this research will significantly reduce investment risk by increasing the lifetime of the CSP plant components. In the past, the majority of the hot corrosion evaluations have been performed for waste incinerators, gas turbine engines, and electric power generation (steam-generating equipment) applications for different materials, molten-salt systems, and coatings. Containment materials and resistant coatings for supercritical CO 2 , molten salts and liquid metal alloys have not being evaluated for CSP applications. We plan to understand the underlying degradation mechanisms to select protective approaches such as anodic passivation, cathodic protection, and coating designs.The novelty of the proposed research is the development of protective coatings and working conditions for materials in contact with high temperature TES and HTF. Current state-of-the-art materials and protection methods are non-existent. Novel approaches are: the use of graphite nanomaterials to enhance the non-wettability of the aggressive fluids with the coating; self-healing behavior of Si-coatings in liquid Al-Si alloys; anodic passivation in molten salts to protect metallic substrates and the modeling prediction of attack in liquid metal alloys.

14 SOLAR ENERGY↗

Advancement of Supercritical Carbon Dioxide Technology through Round Robin Testing and Fundamental Modeling

Growing interest in supercritical carbon dioxide (sCO 2 ) cycles for advanced reactors is driving the need for corrosion data on candidate plant materials. The sCO 2 Brayton cycle is being considered for power conversion systems for a number of nuclear reactor concepts including the sodium fast reactor, fluoride salt-cooled high temperature reactor, high temperature gas reactor, and several types of small modular reactors. Multiple organizations have developed test facilities to address the corrosion data knowledge gap in high temperature, high pressure sCO 2 environments but, to date, there has been no formal test program among these organizations to validate the consistency of the data they produce. A demonstration of comparable and reproducible results enables a coordinated effort to explore the sCO 2 parameter space relevant to advanced reactor technology. This proposal establishes a round robin test plan for sCO 2 corrosion testing and the organization of a sCO 2 Materials Group to guide future materials testing directions. Furthermore, this proposal outlines efforts to elucidate the mechanisms of sCO 2 corrosion by performing identical tests in supercritical steam, testing model alloys with various composition and environmental conditions, accompanied by modeling efforts to study rate controlling mechanisms of corrosion and to help understanding the effects of impurities.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗