Terrestrial Energy – Integrated MSR (IMSR)
The Integral MSR is also based on the MSR Experiment but has been modified to have a more sealed, passive approach. The design team is based in Canada with international involvement and support. An 80 MWth prototype reactor is proposed.
Operating in the thermal spectrum with a graphite moderator inside the sealed unit, it can fit on the back of an articulated truck. This unit contains the fuel salt, moderator, heat exchangers and pumps. The plant is fuelled with 5% low enriched uranium where the U-235 is denatured with U-238. This core is modular, designed for a high power density and replacement after a seven year cycle in a plant with an overall lifetime of over thirty years. This ‘seal and swap’ approach reduces on site complications and risks. Using low enriched uranium, it has a fuel cycle with which regulators are familiar. This proposal is suitable for developing fully and launching commercially immediately.
Terrestrial Energy’s IMSR features self-contained reactor Core-unit, where all key components are permanently sealed for operating lifetime. At the end of 7-year design life, the IMSR Core-unit is shut down to cool. Power is switched to a new IMSR Core-unit, in an adjacent silo within the facility. Once sufficiently cool, the spent IMSR Core-unit is removed and prepared for long-term storage, a process similar to existing industry protocols for long-term nuclear waste containment. The sealed nature of the IMSR Core-unit offers low-cost operational safety and simplicity.
Dr. David LeBlanc presented for Terrestrial Energy at TEAC7 (Thorium Energy Alliance Conference #7), held in 2015 Palo Alto.
Flibe Energy - Liquid Fluoride Thorium Reactor (LFTR)
Flibe Energy, one of the first to resurrect the molten salt reactor concept, and based in the USA, proposes a 2MWth two fluid breeder design. It is based on work carried out by the Oak Ridge National Laboratory team in the 1970’s. It operates in the thermal spectrum moderated by graphite. Its fissile element is uranium-233 which is bred from thorium in a blanket salt at the outer edge of the reactor core.
Kirk Sorensen estimates that it will cost "several hundred million dollars" to get to the first LFTR
Martingale Inc. – ThorCon
The ThorCon design is a single fluid thorium converter reactor that operates in the thermal spectrum. It is in principal similar to the MSR Experiment and its fuel is denatured using a combination of U-233 from thorium and U-235 enriched from mined uranium. Its core is graphite moderated and the full scale version runs at 550MWth. A centralised facility is proposed to reprocess the spent fuel salt from multiple plants. The design team comes from a shipping background and brought in nuclear expertise from members of the MSR community from across the United States. As a concept, a pilot scale version of this plant would be similar to the MiniFuji, a concept that the Japanese have been working on for a long time
Moltex Energy – Stable Salt Reactor (SSR)
The Stable Salt Reactor has a design team based in the UK. It is a fast spectrum pool type reactor. Unlike all the other design concepts considered, its fuel is static and is not derived from the two molten salt reactors developed at Oak Ridge National Laboratory. Its static fuel concept was actually correctly rejected as unsuitable for an aircraft borne reactor by ORNL and apparently never reconsidered when the program moved to ground based reactors. The full size version is proposed at 1GWe and the prototype at 150MWth, but run at a lower power.
Seaborg Technologies – Seaborg Waste Burner (SWaB)
The SWaB prototype proposal is a 50 MWth single fluid reactor that operates in the thermalepithermal spectrum. It is graphite moderated and fuelled by a combination of spent nuclear fuel and thorium. The design team based in Denmark, is a combination of physicists and chemists from the Niels Bohr Institute and the Technical University of Denmark. It is designed to take spent fuel pellets directly for de-cladding and insertion into the fuel salt.
Transatomic Power Reactor (TAP)
Transatomic Power’s proposed design is a 20MWth demonstration reactor which is similar to the MSR Experiment except for its utilisation of zirconium hydride (instead of graphite) as a moderator and LiF-based salt (instead of a FLiBe-based salt). These changes enable a twenty fold increase in power density and the use of very low enriched fuel. It operates in the thermal spectrum and with a significant neutron flux in the fast spectrum. It is a single fluid configuration.
SOURCES - Youtube, Energy Process Development, Moltex Energy, Thorcon, Terrestrial Energy, Flibe Energy