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Molten salt nuclear reactor ‘with no moving parts’ could operate from 2029

Professional Engineering

How a MoltexFlex power plant could look, showing rows of modular Flex reactors
How a MoltexFlex power plant could look, showing rows of modular Flex reactors

A new type of nuclear reactor that uses molten salt fuel and coolant could offer cheap and low-footprint power, its developers have claimed.

With no moving parts and a ‘simple’ design, MoltexFlex said its Flex reactor could “protect generations of consumers from rising energy bills, without resorting to fossil fuels”.

A prototype has not yet been built, a MoltexFlex spokesman told Professional Engineering, but the Cheshire firm aims to have a first-of-its-kind reactor in operation by 2029. It hopes to build 500MW power plants further down the line – comparable to the capacity of other nuclear power stations in operation – which it claims could be built in projects lasting 24 months.

Described by the company as “simple in both design and operation”, the reactor uses a patented system with two molten salts – one acting as a fuel while the other circulates as a coolant. This allows heat from the reactor to be extracted through natural convection, without the need for pumps.

“In other molten salt reactors, where the fuel is also the coolant, the complex fuel salt circulation system – with pumps, filters, conditioning units and heat exchangers – is exposed to the intensely radioactive fuel salt. This puts severe demands on those components and makes monitoring and maintenance very challenging,” MoltexFlex said.

Because of its simplicity, the company said the Flex does not need expensive steel and concrete structures, reducing operational and maintenance costs. 

The lack of moving parts will also mean it can quickly respond to changes in energy demand, the firm added, automatically entering an idle state or rapidly returning to full power. This could make it “an ideal complement to wind and solar power”. An estimated cost of £40 per MWh is comparable to the cost of wind energy.

“We recognised the need for an energy supply that can support renewables when the sun doesn’t shine or the wind doesn’t blow. In the Flex reactor, we have a solution for consumers and countries alike,” said MoltenFlex CEO David Landon.

Each power plant site could contain different configurations of modular Flex reactors, the company said, each with thermal power of 40MWt, equivalent to 16MWe.

An array of 16 units with 256MWe could be deployed in combination with a thermal storage facility to deliver 750MWe during the most demanding eight hours of each day, the company suggested.

The reactor could be operated with the same skills and equipment used in a fossil fuel plant, the company said, lasting 60 years with only two scheduled breaks to refuel. 

“The Flex reactor provides the safety net of affordable domestic energy, but is versatile enough for applications ranging from decarbonising heavy industry to powering cargo ships,” Landon said.

The 750°C heat produced by the reactors, which would be roughly the size of a two-storey house, could also be used for water desalination or hydrogen production. 

Plans for the reactor are based on research conducted in the MoltenFlex laboratory in Warrington.

Parent company Moltex Energy has separate plans for a stable salt reactor in Canada, which would use recycled nuclear waste as fuel.


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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.

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