Tractebel to assist Thorizon in MSR development

Thorizon - a spin-off from NRG, which operates the High Flux Reactor in Petten - is developing a 250 MWt/100 MWe molten salt reactor (MSR), targeted at large industrial customers and utilities. Thorizon aims to construct a pilot reactor system before 2035.

MSRs use molten fluoride salts as primary coolant, at low pressure. They may operate with epithermal or fast neutron spectrums, and with a variety of fuels. Much of the interest today in reviving the MSR concept relates to using thorium (to breed fissile uranium-233), where an initial source of fissile material such as plutonium-239 needs to be provided. There are a number of different MSR design concepts, and a number of interesting challenges in the commercialisation of many, especially with thorium.

The molten salt fuel adopted by Thorizon uses a combination of long-lived elements from reprocessed used nuclear fuel and thorium. The reactor will be able to recycle long-lived waste from existing nuclear facilities.

The Thorizon One concept is unique in that the core is composed of a set of cartridges that is replaced every five to ten years.

Thorizon's molten salt reactor design (Image: Thorizon)

According to Thorizon, its concept offers additional advantages in terms of safety, time to market and costs. Firstly, the reactor only generates energy when salt is circulated through the cartridges. If the pump stops, the reactor shuts down. Secondly, the cartridge design enables the use of existing and proven materials and components, minimising development and licensing timelines. Thirdly, cartridges are efficiently produced in series off-site. They contain all primary systems, together with low-pressure operations, which results in a lean reactor building.

"For several years, Tractebel has been a frontrunner in the deployment of SMRs, which we believe will contribute to achieving carbon neutrality by 2050," said Vincent Schryvers, Business Manager of the Netherlands, Tractebel. "We are now proud to support Thorizon for the development of a Generation IV reactor. This ground-breaking technology will close the fuel cycle and make the circular economy a reality in the nuclear sector. Thanks to its flexibility, this advanced nuclear reactor concept could contribute to addressing the challenges both of industry decarbonisation by providing heat for industrial processes and of energy security by producing electricity for households."

"The expertise Tractebel has built while supporting operating nuclear power plants across Europe for decades, and more recently working on multiple small modular and innovative reactor concepts is invaluable for a start-up like ours," added Thorizon CEO Kiki Lauwers. "The large and experienced team in Belgium is ideally suited to help us make the connection between the Netherlands and France. We very much look forward to working together with the Tractebel team in our offices in Amsterdam and Lyon."

Thorizon said in August 2022 that it will collaborate closely with several parties on the development of its reactor concept, such as France's Orano and NRG, the Dutch producer of medical isotopes and operator of nuclear research infrastructure. Together with EPZ, operator of the Borssele nuclear power plant, Thorizon will investigate the possibility of building the first reactor on the plant site. A broader consortium of research institutions including TU Delft and DIFFER, component suppliers and industrial service providers are supporting this development.

Earlier this month, Thorizon announced it had signed a strategic partnership agreement with French ultra-compact molten salt fast neutron reactor developer Naarea to advance the development of MSRs in Europe. That partnership aims to create the best conditions to: pool resources for safety and security demonstrations and chemical, industrial and strategic knowledge in molten salt technology; develop shared laboratories and test facilities; secure access to reprocessed fuel materials needed for molten salt fuel synthesis; provide the market with a range of complementary energy solutions with a common technology basis; and increase political and public support for MSR technology.