The most abundant, most concentrated energy
Nuclear fuel is highly concentrated and can provide abundant, continuous power day and night. The fissioning of a uranium atom releases the order of a million times as much energy as the chemical oxidation of a single atom of carbon. During the early days of nuclear power this led to claims that it would be “too cheap to meter”. Fortunately, the Earth contains abundant material for generating zero-carbon energy from nuclear power stations. Indeed there is enough to power the world’s energy-hungry economies for millennia. Today’s urgent challenge is to develop reactors that release this energy safely, at a cost competitive with fossil fuels. How can that be done?
Problem of solid nuclear fuel…
All of today’s nuclear power stations use solid pellets for their fuel, posing a danger that is expensive to overcome. Two of the radioactive isotopes produced by the fissioning process (caesium137 and iodine131) carry easily in the air, representing a public safety hazard if released. They must therefore be contained under high pressure inside reactor vessels, and this makes solid fuelled nuclear power uncompetitive in today’s electricity markets.
…Solved by liquid nuclear fuel
During the 1960s American engineers solved the problem of solid nuclear fuel. If ordinary table salt is heated to around 300oC it melts, and nuclear fuel can be dissolved into a range of molten salts, including sodium chloride. With this method the troublesome caesium and iodine fission products react chemically with the salt, becoming stable salts themselves such as caesium chloride and sodium iodide. Crucially, this means they are unable to become airborne in any more than trace (safe) quantities. In addition there is no need to keep the fuel under pressure, obviating the need for expensive pressure vessels.
Numerous Molten Salt Reactor proposals
In recent years, with the dire need for a reliable, competitive zero carbon electricity supply, the idea of molten salt reactors has been resurrected. Start-up companies, notably in the US, Canada, UK and Denmark are rushing to produce the first cheap, safe electricity from a molten salt reactor. This report describes the proposals as of June 2015. Its remit was to select the reactor most suited for development in the UK.
Who will win the race?
Three strong reactor proposals:
|Organisation (Website)||Reactor name||Description||Typical capacity||Price /MWh||Planned pilot|
|Thorcon||Thorcon||Thorium MSR on a ship||500 MWe||$30||2022|
|Terrestrial Energy||Integral Molten Salt Reactor®||Replaceable core that lasts 7 years||195 MWe||$40-50||2022|
|Moltex||Stable Salt Reactor||Burns nuclear waste in static tubes.||1 GWe||$52||2027|
Moltex Stable Salt Reactor:
The Stable Salt Reactor Wasteburner eliminates the main hazards present in today’s pressurised water reactors, and does not introduce new ones. That is why it has been independently estimated to beat fossil fuelled electricity on price.
From energy poverty to abundance
When molten salt reactors begin generating electricity cheaper than gas turbine power stations (currently the cheapest for reliable power), today’s assumed paradigm of energy poverty will disappear, and deep worldwide cuts in emissions will finally become possible. For example, water desalination, currently a high emission process, can become zero emission.
The switch from gasoline to electric vehicles will represent direct emission cuts. The waste heat from molten salt reactors could also be used to power numerous industrial energy intensive processes such as steel or cement manufacture.
Note: natural gas is expected to remain cheaper and will likely need carbon pricing to substantially eliminate it from industrial and domestic heating.
However, opportunities for engineering companies will abound.
History of molten salt reactors:
The technology was not fully developed during the 1960s, in part because their molten salt mixtures caused unacceptable levels of corrosion. However, that problem is now solved. Today’s stainless steel tubes that are certified for use with solid pellets can be galvanised with zirconium, protecting them from molten-salt-based fuels.
Thorium, nuclear fuel in general and expected new reactor development:
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