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Molten Salt Applications In Nuclear Hydrogen and Electricity Production
Principal Investigator: Peterson

Molten fluoride salts provide enormous potential for applications in fission and fusion energy systems. Created using mixtures of fluoride salts with high chemical stability, including LiF, NaF, KF, BeF₂, and ZrF₄, molten salts have properties similar to water, but boil at temperatures around 1400°C. In collaboration with ORNL and SNL, UC Berkeley is currently leading university research in the application of molten salts to cool coated-particle graphite fuel in a reactor system called the Advanced High Temperature Reactor (AHTR). The AHTR provides a potentially major advance over current high-temperature gas-cooled reactor designs, because it can deliver heat at a substantially higher average temperature, and can achieve thermal powers approximately four times larger from an equivalently sized vessel. Multiple-reheat helium Brayton cycles can provide AHTR thermodynamic efficiencies above 50%. Work on molten salts at UCB includes studies of fundamental thermophysical properties, and heat exchanger and system designs for molten-salt applications

Research Sponsors: ORNL, SNL

Advanced High-Temperature Helium Brayton Cycles
Thermal Hydraulics Group, Thermal Labs IFE Experiment page, Peterson
Principal Investigator: Peterson

Gas turbines operate at much higher average pressures than steam turbines, and thus are more compact and substantially less expensive. As occurred in the fossil energy industry, where natural gas fired turbines could be built for much lower costs than steam-cycle coal plants, nuclear power plants will evolve in the same direction. Closed-cycle helium power conversion will be demonstrated in the Next Generation Nuclear Plant, to be built at Idaho National Laboratory. UCB is studying advanced high-temperature closed helium cycles, based on this NGNP technology, that could be used with future molten-salt and liquid metal cooled fusion and fission energy systems. Multiple reheat stages, and high-pressure operation, have been shown to further increase efficiency and substantially reduce capital costs. This has major implications for fusion energy production, where the use of the helium coolant, instead of steam, also greatly simplifies the management of tritium.

Research Sponsors: DOE-OFES, SNL

Advanced Ceramic Composite Heat Exchangers for High-Temperature Fission and Fusion Applications
Thermal Hydraulics Group, Thermal Labs IFE Experiment page, Peterson
Principal Investigator: Peterson

The production of hydrogen using thermochemical processes requires heat delivered at temperatures between 800°C and 1000°C. Metallic materials have great difficulty retaining strength in this range. In this work, UCB is developing highly compact melt-infiltrated carbon-carbon composite heat exchangers, that can exchange thermal energy between high-pressure helium, molten fluoride salts, and thermochemical hydrogen process fluids. Because the carbon coatings of these heat exchangers are highly resistant to fouling by the precipitation of metals, these heat exchangers are also of great interest for inertial fusion applications, where resistance to plugging by target debris is an important goal.

Research Sponsors: UNLV/DOE-NE

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Thick Liquid Protection of Inertial Fusion Energy Chambers
Thermal Hydraulics Group, Thermal Labs IFE Experiment page, Peterson
Principal Investigator: Peterson

In fusion energy systems, 80 percent of the energy from fusion reactions is released in the form of highly energetic neutrons. This energy creates a major challenge for structural materials. First recognized in the 1970’s, the use of a liquid layer to absorb the neutrons and protect the structures can result in greatly increased lifespan, more compact chambers, and greatly improved economics. These advantages have made thick-liquid chamber protection the base-line approach for Z-pinch and heavy-ion inertial fusion. At UCB, thick-liquid research focuses the use of molten salts to protect fusion chambers, using combinations of experiments, analysis, and detailed numerical models.

Research Sponsors: DOE-OFES, SNL

Mixing Processes in Large, Stratified Enclosures

This project investigates scaling methodologies, fundamental governing equation derivations, and numerical and analytical analysis for mixing in large, stratified enclosures. The applications focus on mixing processes in light-water reactor containment buildings, high-level waste tanks, and tunnels at the Yucca Mountain geologic repository.

Research Sponsors: Westinghouse, DOE-EM

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