Nuclear fission in the energy system – Technical challenges, new developments and global perspectives

Munich, 29 November 2023

Can nuclear energy play a part in a more environmentally friendly energy system? Opinions on this matter differ, as came to light at acatech am Dienstag on 21 November in cooperation with the Swiss Academy of Engineering Sciences SATW.

In his welcome address, acatech President Jan Wörner thanked SATW for their cooperation in hosting the online event, before going into the terms “nuclear fission” and “nuclear fusion” in greater detail. Both of are ways of generating power. In nuclear fission, which is used to generate nuclear energy, atoms are split apart. Nuclear fusion, on the other hand, refers to the collision and combining of smaller atomic nuclei using laser beams to create larger atomic nuclei. Both processes, Jan Wörner went on to say, occur in nature: nuclear fission in the Earth’s core (which accounts for around half of geothermal energy), nuclear fusion in the sun.

Innovation in the field of nuclear technologies

Wolfgang Kröger, Professor Emeritus of Safety Technology/Risk Analytics at ETH Zürich and SATW member, gave an overview of the current status and of the development in the field of nuclear technologies. Following the political decision to replace fossil fuels gradually – and with electricity requirements soaring – attention has increasingly shifted back onto nuclear technologies, and nuclear fission in particular. Now it’s a matter of examining all the options for energy generation from the point of view of the strengths and weaknesses of each option.

Around ten per cent of the electricity produced worldwide is nuclear generated. The proportion in Germany is vanishingly small, the last nuclear power plants in Germany having been shut down in 2023, while in Switzerland nuclear power accounts for 29 per cent and in France a whopping 69 per cent of the electricity produced.

The advantages of nuclear technologies, Wolfgang Kröger continued, include the low carbon emissions, which are comparable to wind energy and lower than roof-mounted solar panels by a factor of four. Another advantage is the immense energy density of the fuel (U-235 enriched uranium), which means material and space requirements are low. In addition, uranium deposits can be found in many countries, so shortages are not envisaged, said the expert.

However, conceded Wolfgang Kröger, safety systems and the tricky disposal and final storage of waste resulting from nuclear power generation are a major challenge.

Advances in nuclear technology

Globally, many new technical developments are happening in nuclear technology. The light water reactors common today are referred to as second-generation reactors. “Evolutionary” third-generation designs are improvements on the Gen II class, with active safety systems to rule out core meltdowns and a containment design with passive systems to contain accidents and avoid the release of radioactivity. “Revolutionary” designs (Generation IV) have passive safety systems that do not require emergency power or active intervention to avoid accidents with serious consequences. They use coolants such as liquid metals (sodium, lead) or molten salt. Wolfgang Kröger mentioned Accelerator-Driven Systems and the Dual Fluid Reactor as further examples of revolutionary designs, where the fuel particles are dissolved in a molten salt. There are high hopes for Small Modular Reactors. The “small” refers to the power capacity. It remains to be seen whether and in what use cases these reactors prove economical; possibly to generate process heat or for hydrogen production.

The role of nuclear fission in the power system

Jonas Savelsberg, economist and Senior Researcher at the Energy Science Center and at the Center for Energy Policy and Economics of ETH Zürich, spoke about the role of nuclear energy in the (European) power system, in which the proportion of renewable energy is steadily growing. Worldwide demand for wind and solar energy, and for battery storage systems, is increasing – and prices are consequently falling. In many parts of the world, wind and solar power plants are already cheaper than new coal-fired or gas-fired power stations. However, the cost of nuclear energy has risen in recent years.

Nuclear energy and society

Addressing the social implications of nuclear energy, Sophie Kuppler, sociologist and head of the research group “Radioactive Waste Management as a Socio-Technical Project” at the Institute for Technology Assessment and Systems Analysis (ITAS) / Karlsruhe Institute of Technology (KIT), stated that technologies and the social are inextricably linked: the “best” technology (from the point of view of science and technology) doesn’t always win through. Rather, the values and interests of certain social groups play an important role in the development of technology. Germans’ associations with nuclear technology are military use on the one hand and commercial promise on the other. Nuclear energy is also being spoken of at the moment as a lifeline in the climate crisis, whereas safety and risk concerns, geopolitical dependencies and final disposal issues are being given hardly any consideration. Sure, the debate about nuclear energy in Germany is “special”, but it’s just a “special” in every other country with its specific cultural background.

In his commentary, Jan Wörner pointed out the various aspects of relevance in the conflict between technology and society; especially climate neutrality, economic aspects and sovereignty issues. One thing is certain: nuclear energy is a field of the technical sciences that requires a great deal of research.

Lively discussion in science and society

The discussion moderated by Denis Weitze, acatech Office, looked at the cost estimates (for power-plant construction and operation) and price trend of various types of energy from different perspectives. The participants were sceptical about the extent to which renewables alone could meet global energy requirements. The situation concerning nuclear energy in Germany is special; other countries are taking different paths.

It is always hard to predict the future – in this instance, the future share of nuclear energy in the energy mix – noted Sophie Kuppler. One can talk about the various alternatives and options for action and describe related developments.

Wolfgang Kröger deduces from many studies that we can expect the global share of nuclear energy to increase against the backdrop of net-zero electricity targets. However, Europe has been lagging behind in recent years and has lost the ability to build nuclear power plants quickly. In this respect, new reactor types are of great interest, some of which are at the demonstration stage (albeit not in Europe). He foresees fewer dependencies with regard to fuel supply. Also, clear progress is being made on the deep geological storage of radioactive waste.

The fact is that opinions on nuclear energy differ widely, said acatech President Jan Wörner, summing up the event, making it all the more important to continue the debate, consider new approaches and do even more thorough research.

Further information

SATW factsheet “Nuclear energy technologies: overview of current status and development”