The nuclear reactors of the future

The claimed advantages of fast neutron reactors (FNRs):

• Fast neutron reactors can use all the plutonium produced by the current fleet of reactors or by themselves, without restriction.
• They can burn any type of uranium. By using all the uranium extracted from the ground, they increase the energy that can be extracted from a given mass of natural uranium by a factor of almost 100.
• They make it possible to reduce the radiotoxicity, the half-life and the volume of final waste.

Our Belgian pride and joy, MYRRHA, is also a fast neutron research reactor.

Thorium has many advantages. The metal thorium-232 is more abundant than uranium and can be used almost 100 per cent.

Thorium could support the development of a new nuclear technology. This is particularly true in countries such as India and China, which possess significant thorium resources. Both countries are conducting major long-term development programmes on thorium-fuelled reactors. China and the United States are funding a research programme to develop this technology on an industrial scale. China has even stated its intention to build a reactor by 2030. The combination of molten salt technology and thorium offers, on the one hand, safety and energy efficiency and, on the other, abundance and the elimination of long-lived waste.

Numerous initiatives are being developed around the world, including in Europe. However, the use of thorium requires the establishment of a new nuclear sector, distinct from the current one. Research is being carried out in France by the National Centre for Scientific Research in Grenoble. It must be recognised that thorium may represent a potential option in the very long term. Indeed, the uranium fuel cycle is perfectly under control and the supply of uranium is guaranteed for at least the next 200 years.

A few examples from around us

In December 2013, Orano (formerly AREVA) and Solvay signed an agreement aimed at developing thorium. This agreement includes, in particular, a Research and Development programme to investigate, amongst other things, its use as a potential fuel for next-generation nuclear power stations.

In the Netherlands, scientists at the Nuclear Research and Consultancy Group (NRG) in Petten began experiments in August 2017 to gain a better understanding of various aspects of how a molten salt reactor using thorium as fuel operates. These experiments are being conducted jointly with the European Commission’s Joint Research Centre in Karlsruhe. The project is called SALIENT, which stands for SALt Irradiation ExperimeNT.

In Grenoble, researchers at the CNRS are studying the advantages and disadvantages of molten salt reactors using thorium.

A molten salt reactor is based on the principle of integrating the fuel directly into the coolant. This represents a fundamental difference from current reactors, as the fuel is in liquid form rather than solid.

The aim is to enable both energy production and fuel recycling to take place within a single facility. Molten salt reactors have the potential to provide abundant, safe, clean and affordable energy for thousands of years.

Molten salt reactors can also be designed to provide automatic load following. This property is essential in a context where some of the electricity is generated by intermittent sources such as solar and wind power.

Uranium molten salt reactors

Some reactors will continue to use enriched uranium-235. They form part of the fourth-generation reactor technologies that could be available by 2030.

The Canadian company Terrestrial Energy is developing a molten salt reactor called the IMSR (Integral Molten Salt Reactor) using fuel based on uranium-235 enriched to around 5 per cent. This reactor is expected to have a deliverable electrical output of 190 MW and, according to its designers, could enter service in the late 2020s or early 2030s. In any case, the Canadian regulator announced in late 2017 that Terrestrial Energy had completed the first of three phases of the ‘pre-licensing review’. This approval from the Canadian Nuclear Safety Commission represents a significant step towards the construction of a fourth-generation reactor. Terrestrial Energy has already decided to build its first power station at the Canadian National Labs site in Chalk River, Ontario.

In addition to generating electricity, this type of reactor could also provide heat for industrial applications such as in the chemical industry and for desalinating seawater.