Molten Salt Reactor (MSR): Nuclear Explained

A new type of nuclear-powered vessel is on the horizon, using the Molten Salt Reactor (MSR). What is MSR? How does it work?

What if you could build a vessel that doesn’t need to refuel for 25 years and could still sail at a higher service speed than normal despite more stringent emission requirements?
This could become a reality. A new type of nuclear-powered vessel is on the horizon, using the Molten Salt Reactor (MSR).

But what is a Molten Salt Reactor? How does it work?


A Molten Salt Reactor (MSR) is an advanced nuclear reactor that uses a liquid fuel. Note that, most conventional reactors use solid fuel instead. The fuel-salt in an MSR contains the uranium fuel which keeps the fuel-salt liquid at high temperature

Nuclear science is of course a very specialized subject. But in simple terms, MSRs operate on the same principle as a current nuclear power reactor. Particulrly, using controlled fission (the splitting of a large atom into smaller atoms to release energy). The heat generated by fission produces steam which drives electricity-generating turbines.

But there is a key difference with the MSR. Molten salt flows in the reactor core, which acts as both a fuel and a coolant. In contrast, current operating reactors use solid fuel rods and require a highly pressurized water coolant system.

This means the MSR generates less waste, and can operate at higher temperatures, which leads to increased efficiencies. Additionally, used at low operating pressures, which can reduce the risk of coolant loss. Therefore, the MSR is considerably safer than current reactor technology and more suited to a maritime applications.

How MSR Works?

By absorbing neutrons from the fission process, natural Uranium can transmute into fissile material, thereby ‘breeding’ some additional fuel. The fast spectrum MSR elegantly consumes this additional fuel, making it more efficient. Imagine a combustion engine that could consume its own exhaust gas!

In an MSR there are no fuel assembly structures like cladding, fuel ducts, and grid spacers which can lose valuable neutrons. This too improves the fuel efficiency and economics of the MSR.

The chloride salt, used in the MSR, melts at above 400 °C and has over 1,000 °C of operating range below its boiling point. Other salts are usable, but the fast spectrum MSR prefers chloride salt (NaCl).

It is the fission (sustained chain reaction) of the uranium which produces the heat that keeps the salt liquid (hence molten salt). Conventional reactors must be shut down to move fuel around or put new fuel in.

In an MSR this can occur while the machine is at full power, by gradual addition of more oxide fuel into the salt. In this regard, the MSR can run for a very long time without stopping.

This allows for very high-capacity factors and improves the economics of power generation. MSRs still must shut down for maintenance, but they will run for a long time between service intervals.

As the liquid fuel circulates around the core chamber of the MSR, powerful heat exchangers pick up the generated heat and transport it to the power conversion system, which generates electric power.

Molten Salt Reactor (MSR): nuclear explained

With few moving parts, no fuel assemblies or coolant to exchange, the MSR can largely operate on its own in a closed chamber, which provides shielding from the external environment.

“New advanced nuclear technologies in small mass manufactured formats can provide 100% clean, reliable and affordable electric power to transform heavy transport and industry to true zero emissions. Without it, we cannot solve the climate change riddle.”


Source: CorePower

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