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Detailed testing of IMSR fuel salt starts

Wednesday, 11 November 2020

Terrestrial Energy and the US Department of Energy's Argonne National Laboratory have begun detailed testing of the fuel salt for Terrestrial's Integral Molten Salt Reactor. The IMSR uses two molten salt streams - a fuel salt that contains the uranium and another salt to transfer heat from the reactor to the electricity generation system.

Detailed testing of IMSR fuel salt starts — A cutaway of the IMSR (Image: Terrestrial Energy)

ANL will use an extensive array of characterisation techniques and advanced laboratory equipment to determine thermo-physical properties of the IMSR fuel salt to regulatory standards. ANL will prepare and test fuel salt mixtures that replicate the fuel salt composition over the full IMSR operating cycle. The laboratory investigations will include melting point determinations, density, viscosity, heat capacity and thermal diffusivity measurements.

Terrestrial said this fuel salt testing programme is part of a broader ongoing confirmatory testing programme for fuel, components and systems used in the IMSR power plant. It said the results of these tests will support licensing applications as first commercial deployment of the IMSR power plants advance.

Terrestrial began working with ANL in 2016 after receiving an award from the US Department of Energy's Gateway for Accelerated Innovation in Nuclear (GAIN) programme, which directs support to the nuclear community commercialising innovative nuclear technologies.

"Our first GAIN award catalysed what is now a full-scope commercial engagement with the lab," said Simon Irish, CEO of Terrestrial Energy USA. "Our strategy is to continue working with world-class laboratories offering expertise in relevant areas, rather than building that testing capability in-house. This strategy keeps our engineering resources focused on the IMSR power plant, rather than developing lab-based R&D capabilities, and is essential to meet our early deployment schedule."

Molten salt reactors use fuel dissolved in a molten fluoride or chloride salt, which functions as both the fuel (producing the heat) and the coolant (transporting the heat away, and ultimately to, the electricity generating equipment). Terrestrial's IMSR builds on 50 years of experience at the USA's Oak Ridge National Laboratory, and integrates the primary reactor components, including the graphite moderator, into a sealed and replaceable reactor core unit with an operating lifetime of seven years.