Could nuclear power make a comeback with future generations of reactors?

New types of nuclear fission reactors, known as “4th generation” reactors, have been under development for the past 20 years. If they deliver on their promises in terms of safety, efficiency and the ability to reduce radioactive waste, they could play a role by 2030-2050. As for nuclear fusion, it is not part of the current energy transition, as its commercial use is not expected before 2100.

The principle of nuclear fission reactors consists of splitting the nucleus of a heavy atom (uranium, plutonium) into two lighter nuclei, called “fission products”, which make up a large part of highly radioactive waste. This “fission” of the nucleus generates a large amount of heat, which is used in most types of nuclear power plants to heat water and produce steam. This steam is then used to drive turbines that generate electricity, as in other types of thermal power plants (coal, gas, etc.).

The first commercial nuclear reactors were commissioned in the 1950s and 1960s. None is in service today. From 1969, the 2nd generation took over. Almost all of the 436 commercial nuclear reactors in operation in 2015, including the 5 Swiss reactors, belong to this 2nd generation (as well as almost all the 61 reactors currently under construction worldwide). The 3rd generation refers to reactors designed from the 1990s onwards, improved on the basis of experience gained in the operation of previous generations of facilities. Few 3rd generation power plants are currently in service; most of them are located in China (EPR and AP1000 types), and about ten are under construction around the world.

Generations 1, 2, and 3 have made incremental improvements to nuclear fission reactor technology. On the other hand, the 4th generation represents a technological breakthrough that could bring several important advances:

• Significantly higher energy efficiency. Some 4th generation reactors could recover 50-80% of the energy contained in uranium, while traditional fission technologies recover only 1%. As a result, the duration of nuclear fuel reserves would be greatly extended, from 60 years with today’s reactors to several thousands of years.
• A significant reduction in the production of high-level radioactive waste. In addition, the possibility of using some of the waste from our current power plants as fuel would allow them to be converted into low- and intermediate-level radioactive waste while generating additional electricity.
• Increased safety compared to current reactors through the more systematic use of passive safety features that delay the need for human intervention and the associated risks.
• Improved financial profitability, but this is highly controversial.

The first commercial 4th generation reactors could be built around 2030. The question of whether the envisaged technologies will be able to deliver on their promises has no clear answer today. Switzerland, along with twelve other countries, is part of the “International Generation 4 Forum”, which coordinates the development of this technology. A possible use of these reactors in Switzerland would first require a review of the decision not to build new nuclear fission plants.

Nuclear fusion is based on a very different principle from fission. In this case, the idea is to fuse light atoms (such as hydrogen) into heavier atoms. In the process, the heat emitted is recovered to produce electricity, as in the case of nuclear fission. Given the scientific and technical challenges that remain to be overcome before the nuclear fusion process can be mastered, it seems highly unlikely that industrial applications will emerge before the end of this century.