Nuclear power: Swiss and Danes research thorium molten salt reactor
Small, modular reactors could help to meet future energy requirements. This is now being researched in Switzerland.
This is how Copenhagen Atomics envisions a nuclear power plant with SMR with a total output of 1 GW.
(Image: Copenhagen Atomics)
The Swiss Paul Scherrer Institute (PSI) will be experimenting with new reactor technology in the future. PSI, which is part of ETH Zurich, is cooperating with the Danish company Copenhagen Atomics. Together, they want to validate molten salt reactor technology and gain experience that could help to plan, approve, build and decommission such reactors. "In addition, data for commercial use and open-source data for the validation of reactor modeling tools will be obtained", according to a PSI statement.
Copenhagen Atomics has been working on the principle of molten salt reactors for almost a decade. The technology has now matured to such an extent that critical experimental tests on thorium molten salt are now required. Prototypes with full-scale reactor circuits already exist in Copenhagen. Fluoride salts made from lithium, thorium and low-enriched uranium are used as fuel. These could be produced in modules the size of a conventional 40-foot container. Copenhagen Atomics believes that thorium molten salt reactors could be used in the long term as breeder reactors, with a LCOE of 20 US dollars/MWh.
In this type of reactor, molten salt is used as a coolant and as a carrier for the fuel. The melts tested so far can be stable up to 1400 °C, explains the German Society for Reactor Safety (GRS). The high operating temperatures should enable high efficiencies and heat extraction for industrial high-temperature processes. In addition, the heat transport properties of molten salt should allow the reactors to be built with significantly smaller dimensions compared to gas-cooled reactors with the same output.
Fewer old risks, more new ones
Copenhagen Atomics advertises these smaller dimensions compared to conventional reactors. The industry normally scales up the size of nuclear power plants to reduce costs, but this also increases the financial risk. The salt reactors are so small and modular that they can be manufactured discounted the cost of conventional reactors. The desired output is achieved by installing several reactors at one site, so-called small modular reactors.
Because less fuel is used in such a reactor, this also reduces the amount of radioactivity that can be released in the event of an accident, adds GRS. However, Small Modular Reactors bring with them new risks. In the case of molten salts, for example, these are their highly corrosive properties. These would have to be considered for coolant pipes, for example.
Whether the new technology – if it can be successfully tested – will be used in Switzerland itself is questionable. In 2017, the Swiss people voted in favor of no more new nuclear power plants being built. However, there are efforts underway in Switzerland to approve and build new nuclear power plants. In March of this year, the Swiss Council of States decided that the government should examine such a scenario.
(anw)
