IMSR400 Photo credit: Terrestrial EnergyOntario-based Terrestrial Energy has announced its upgraded Integral Molten Salt Reactor (IMSR®) nuclear power plant design – the IMSR®400 –with a net 390MW of electric generation capacity for grid supply from twin reactors and generators.  Terrestrial said the upgrade, in response to utility requirements, “further increases the cost-competitiveness of the IMSR®400 as a clean, safe and reliable source of energy”.

“With our upgraded IMSR®400 Generation IV nuclear power plant, Terrestrial Energy is raising the bar for innovative carbon-free technology in terms of cost-competitiveness, resilience, and scalability,” said Terrestrial Energy CEO Simon Irish. “The IMSR®400 has the efficiency, economics and flexibility to play a major role in the clean energy transition including the production of clean hydrogen at industrial scale.”

Terrestrial Energy’s IMSR®400 is one of three small modular reactor (SMR) power plant designs under consideration for deployment at Ontario Power Generation’s Darlington Nuclear Generating Station. It is one of two Generation IV technology candidates, and the only Canadian technology candidate. Terrestrial Energy’s Oakville operation represents the largest SMR power plant technology development project in Canada.

The IMSR®400 is a proprietary power plant design drawing on Generation IV reactor technology developed and demonstrated over many decades. Using Generation IV molten salt reactor technology, the IMSR®400 generates electric power 50% more efficiently than conventional nuclear power plants that use water cooled and moderated reactor technology. With this efficiency improvement, the IMSR®400 has a reduced capital requirement and waste footprint, and improved economics per kWh of electricity for new nuclear power plants.

The Generation IV reactor technology class was defined in 2001 by the Generation IV International Forum (GIF), set up by international treaty and overseen by the Organisation of Economic Cooperation and Development (OECD), to which Canada and the USA were founding signatories. GIF identified six reactor types, including the molten salt reactor, as Generation IV technologies that offer improvements in cost, safety, versatility and waste, and embody the future of civilian nuclear power generation.

Since early 2016, when it became the first Generation IV reactor developer to submit a power plant design to the Canadian Nuclear Safety Commission (CNSC), Terrestrial Energy has been committed to the CNSC’s Vendor Design Review process. It completed Phase 1 in 2017 and expects to complete Phase 2 by early 2022. Since late 2019, the company has also been engaged with the CNSC and the US Nuclear Regulatory Commission (NRC), as the two regulatory agencies collaborate to develop licensing practices to support efficient reviews of Generation IV NPPs.

The IMSR®400 uses nuclear fuel at standard enrichment – currently the only Generation IV SMR power plant designed to do so. This avoids the considerable cost and time of re-licensing uranium enrichment plants and removes hurdles to commercialisation, hastening deployment. The company announced an agreement on 17 August with Westinghouse and the UK’s National Nuclear Laboratory to provide the IMSR®’s nuclear fuel supply, the first Generation IV SMR to have such an agreement.


IMSR400 Photo credit: Terrestrial Energy