Growing interest in molten salt reactors

24 September 2019

With recent research milestones and funding achievements the development of molten salt
reactors is moving forwards.

Moltex Energy, which is developing the Stable Salt Reactor (SSR), has raised £6 million ($7.5 million) in funding through online investment platform Shadow Foundr.

Moltex Energy, a privately-held international company based in the UK and Canada, has already secured a number of international patents for SSRs. It is part of the UK government's Advanced Modular Reactor initiative and, in collaboration with NB Power, Moltex is progressing with plans to demonstrate the first operational Stable Salt Reactor in New Brunswick, Canada.

In July, Moltex announced it would build a demonstration of its SSR at the Point Lepreau site in Canada under an agreement signed with the New Brunswick Energy Solutions Corporation and New Brunswick Power. Also in July, the US Department of Energy’s Advanced Research Project Agency-Energy awarded Moltex a $2.55m grant to develop
Composite Structural Technologies and to help commercialise and scale up its Wasteburner SSR. Earlier, in March, Italian utility Fermi Energia signed a preliminary deal with Moltex to install a small modular reactor (SMR) in Estonia.

The latest funding, Moltex says, will support the company through the pre-licensing process in Canada and will allow the further development of the business in the UK.

Almost half the funding came from 170 investors in the world’s first 'crowdfunding' campaign for nuclear fission. The initial funding target of £4 million was achieved in less than a week, with Moltex closing the round soon after £2 million was over-subscribed at £6 million.

Moltex said: "With the UK pledging to be net-zero carbon economy by 2050, intermittent renewable sources cannot do the whole job alone: a variable power source is required to bridge the gap between supply and demand. Today that source is gas. Moltex's new fission technology has a variable output and can replace gas in the national grid, making zero carbon electricity generation a reality."

The company's aim is to deliver electricity at lower costs than today’s fossil fuel sources, and at scale globally, thereby having a meaningful impact on climate change.

Moltex said its SSR is an advanced modular reactor. Existing stockpiles of used nuclear fuel can be used as the fuel source, and the energy can be stored using GridReserve technology, to enable a larger expansion of renewables in a carbon-free grid.

The molten salt reactor (MSR) is an invention of the American nuclear physicist Alvin Weinberg. The basic technology was first demonstrated at Oak Ridge National Laboratory from 1965 to 1969.

Renewed interest in the MSR concept in part 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 designs. Other companies currently developing MSR technology include:  MAN Energy Solutions, Kairos Power, Enesoon Holding, Copenhagen Atomics, Terrestrial Energy (IMSR), ThorCon Power, Elysium Industries, Flibe Energy, Lightbridge, Steenkampskraal Thorium Limited, and Shanghai TaiYang Technology Co.

Molten salt progress at Petten

Research on MSRs is also underway at the High Flux Reactor at Petten in the Netherlands, where the Nuclear Research and Consultancy Group (NRG) is collaborating with the European Commission’s Joint Research Centre (JRC) in Karlsruhe, which has manufactured the salt samples for testing. JRC has developed fuel comprising lithium and thorium fluoride salts. NRG started irradiating samples of this fuel in the High Flux Reactor in August 2017.

NRG announced on 17 September that a “historic milestone” had been reached with the successful completion of a test irradiation of molten fuel salts. “Now that the research in the reactor has been completed, the irradiated salt can be further investigated in the NRG laboratories. Only then can we really see how the salt has reacted to the irradiation in the reactor," said NRG researcher Ralph Hania.

SALIENT-01 is the first irradiation experiment within the molten salt reactor research programme that NRG has been carrying out since 2015. NRG was a pioneer in this field at the time.

The molten salt programme at NRG has grown considerably since 2015 and includes research into suitable construction materials, the processing and purification of molten salt, and the processing of residual products.

More projects are planned within the programme that will start soon. In the autumn, further irradiation is planned with the aim of investigating the radiolysis of salts, a process that occurs when fuel salts cool in a radiation field and in which gases are formed. Subsequent analysis will be undertaken by NRG and JRC. Part of this post-irradiation research is being carried out within the framework of the new European research project SAMOSAFER that is being coordinated by TU Delft.

Another irradiation experiment in the High Flux Reactor is planned to start in early 2020 which will examine corrosion resistance of candidate alloys for construction of an MSR.

In February, NRG signed a contract with Terrestrial Energy to carry out testing of materials, including graphite, for key components of its Integral Molten Salt Reactor (IMSR). The agreement will see NRG provide expert technical services to support Terrestrial Energy's "in-core" materials testing and the development of its generation IV plant. In March 2018, Terrestrial Energy signed a technical services agreement with JRC to perform confirmatory studies of the fuel and primary coolant salt mixture for the IMSR.

NRG started irradiating samples of molten salt fuel in the High Flux Reactor 2015 (Photo: NRG)
Moltex's vision of an SSR plant (Photo: Moltex Energy)
How Terrestrial Energy’s integral molten salt reactor might look (Photo: Terrestrial Energy)

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