Molten-Salt Fusion Reactors and Molten-Salt Fission Reactors – Dr. Charles Forsberg @ ORNL MSRW 2019

Dr. Charles Forsberg observes technological overlap between Molten-Salt Reactor (fission) development and Fusion Reactors due to manufacturing breakthrough of Rare-Earth Barium Copper Oxide (REBCO) Superconducting Magnets onto steel tape.

REBCO superconducting tape enables doubling magnetic fields.

Size of magnetic fusion system for any given power output varies as one over the fourth power of the magnetic field. Higher magnetic fields can shrink fusion system size by an order of magnitude, power density in the fusion blanket increases by an order of magnitude.

Higher power densities in the blanket make it difficult to cool solid blankets. High magnetic fields create large incentives to have a coolant with low electrical conductivity to avoid coolant/magnetic field interactions.

REBCO Fusion Favors a Molten-Salt (particularly FLiBe Salt) Blanket.

Why Flibe (Li2BeF4) Salt?

Maximize tritium production (90% Li-6) to produce sufficient tritium for self-sustaining fusion machine. Beryllium (n, 2n) reaction generates more neutrons. Lithium plus neutron yields tritium. Excellent heat transfer relative to other salts.

Flibe (Li2BeF4) Salt Fusion Blankets Applicable to all Fusion Technologies. ARC is the First Design with REBCO Superconducting Magnets; Other Fusion Systems Likely to Follow with Incentives for Flibe Blankets.

Synergisms Between Flibe-Salt-Cooled Fission and Fusion Reactors:
•Basic science of salts
•Design tools
•Technology (materials, tritium control, salt purification, power cycles)
•Supply chains (equipment, FLiBe salt, lithium isotopic separation)

Synergisms Will Accelerate Development of All Salt Systems.

Dr. Charles Forsberg presentation given at Oak Ridge Molten Salt Reactor Workshop 2019 [ ORNL MSRW 2019 ]: https://msrworkshop.ornl.gov/

THE PAPER: https://doi.org/10.1080/00295450.2019.1691400
Fusion Blankets and Fluoride-Salt-Cooled High-Temperature Reactors with Flibe Salt Coolant: Common Challenges, Tritium Control, and Opportunities for Synergistic Development Strategies Between Fission, Fusion, and Solar Salt Technologies
Charles Forsberg, Guiqiu (Tony) Zheng, Ronald G. Ballinger & Stephen T. Lam
Received September 12, 2019
Accepted for Publication November 7, 2019

Abstract — Recent developments in high-magnetic-field fusion systems have created large incentives to develop flibe (Li2BeF4) salt fusion blankets that have four functions: (1) convert the high energy of fusion neutrons into heat for the power system, (2) convert lithium into tritium—the fusion fuel, (3) shield the magnets against radiation, and (4) cool the first wall that separates the plasma from the salt blanket. Flibe is the same coolant proposed for fluoride-salt-cooled high-temperature reactors that use clean flibe coolant and graphite-matrix coated-particle fuel. Flibe is also the coolant proposed for some molten salt reactors (MSRs) where the fuel is dissolved in the coolant. The multiple applications for flibe as a coolant create large incentives for cooperative fusion-fission programs for development of the underlying science, design tools, technology (pumps, instrumentation, salt purification, materials, tritium removal, etc.), and supply chains. Other high-temperature molten salts are being developed for alternative MSR systems and for advanced Gen-III concentrated solar power (CSP) systems. The overlapping characteristics of flibe salt with these other salt systems create significant incentives for cooperative fusion-fission-solar programs in multiple areas. We describe the fission and fusion flibe-cooled systems, what has created this synergism, what is different and the same between fission and fusion in terms of using flibe, and the common challenges. We review (1) the characteristics of flibe salts, (2) the status of the technology, (3) the options for tritium capture and control in the salt, heat exchangers, and secondary heat transfer loops, and (4) the coupling to power cycles with heat storage. The technology overlap between flibe systems and other high-temperature MSR and CSP salt systems is described. This defines where there are opportunities for cooperative programs across fission, fusion, and CSP salt programs.

Dr. Charles Forsberg research areas include Fluoride-salt-cooled High-Temperature Reactors (FHRs) and utility-scale heat storage including Firebrick Resistance-Heated Energy Storage (FIRES). He teaches at MIT the fuel cycle and nuclear chemical engineering classes.

Presentation given at Oak Ridge Molten Salt Reactor Workshop 2019 [ ORNL MSRW 2019 ].

Video footage courtesy of ORNL and Dr. Charles Forsberg.

Video presented on this YouTube channel as part of Thorium Remix project. https://thoriumremix.com/