Lorenzo Malerba

Lorenzo Malerba is a nuclear and industrial engineer, with diplomas from both the Politecnico di Milano (Italy) and the Universidad Politécnica de Madrid (Spain), and a PhD in fusion energy materials. In 2000 he joined the Belgian Nuclear Energy Research Centre, SCK•CEN, where he leads a unit devoted to nuclear structural materials modelling and microstructure. He has authored or co-authored more than 100 peer-reviewed scientific articles and about 50 papers that have appeared in conference proceedings or journals. He regularly delivers seminars at various universities and research centres all over Europe and outside. He is currently coordinator of the EERA Joint Programme on Nuclear Materials.

With other renewable energy technologies offering safe and sustainable options for energy production, why do we need nuclear power?

The need to decarbonise the energy system and to slow down climate change is too urgent: we simply cannot afford to exclude any available or envisaged low-carbon technology from the portfolio. As the environmentalist James Lovelock put it a few years ago: "Now that we've made the earth sick it won't be cured by alternative Green remedies like wind turbines or biofuels, and this is why I recommend the appropriate medicine of nuclear energy as a part of a sensible portfolio of energy sources". All technologies can help, if they are developed and used with the twin goals of sustainability and safety kept in mind. It is unlikely that renewable technologies such as those exploiting the sun, wind or oceans as energy sources can completely replace fossil fuels within the next couple of decades. Moreover, the exclusive use of renewable energy would necessarily require the simultaneous implementation of new transmission and storage systems, which are very valuable technologies, but still under development and altogether very costly. In other words, achieving a low-carbon energy economy over the next couple of decades would be very difficult without nuclear energy acting as base-load, with renewables on top: the combination of nuclear and renewables will guarantee a strong energy system. Nuclear energy has the big advantage of being a low-carbon technology that already exists and guarantees high energy output (to produce as much electricity as nuclear plants currently produce in France, half of Belgium would need to be densely covered with wind turbines). Furthermore, nuclear produces energy at a constant rate and at stable, predictable and competitive prices. Almost one third of the electricity in Europe comes from nuclear. Let's remember that the SET-Plan aims to achieve sustainability, but also competitiveness and security of supply: renewable energy is generally quite expensive. Of course there is no supply problem with wind, sun or oceans (except for the variability of the resource), but in the current geopolitical situation security of supply is becoming an increasingly serious problem for the transition of the energy sector. This may impact on fossil fuel use more than the fear of climate change: the response to this must be rapid, and happily there is no problem with nuclear fuel supply. True, there are currently some safety concerns about nuclear energy and the nuclear option certainly does not enjoy wide public support. However, the safety record of nuclear plants in Europe is actually excellent. Moreover, from a research point of view the mature approach to problems is to face them, rather than refusing to resolve them. We are working towards safer and sustainable nuclear energy and, with this aim in mind, materials are key.

What are the main obstacles to the expansion of nuclear energy in Europe and what is needed to overcome these obstacles?

Undoubtedly, the main obstacle is the lack of unambiguous political support to pursue this expansion in many European countries, strongly linked to low public acceptance. After Fukushima, governments that openly support nuclear energy expose themselves to the possible risk of a public backlash: a risk that few administrations are ready to take because of the short-term political consequences, even if hypothetically they are convinced that, in the long term, the nuclear option has clear advantages. In this context, it is generally easier for governments either to take a position against nuclear energy, or not to take any position. As a consequence, nuclear energy is a bit like the 'black sheep' of low-carbon energy, over which renewables are generally given priority (and receive subventions). The large capital investments required to build new plants are not always guaranteed by governments, so the number of new builds remains low and limited to a few countries, thereby reducing the market and further increasing costs. Another consequence is that the number of experts decreases, and so on. Fortunately the situation, including public opposition, is not generalized to all European countries, and other technologies also face opposition (even wind turbines), but the nuclear issue is certainly politically delicate more or less everywhere.

Another problem is the fact that the large investment costs required to build a nuclear power plant imply a long return on investment and this may be discouraging for private investors, especially in conditions of uncertain political support. Competing with new nuclear builds in this respect are conventional power plants that use fossil fuels, where the largest cost is represented by the fuel itself. If the price is affordable (e.g. shale gas in the USA), then the payback is faster.

To address the first problem, an objective discussion on nuclear energy is needed and we scientists should be more engaged in it, but attempts to achieve this often encounter a wall of prejudice and atavistic fears among a section of the public. Words like "nuclear", "atomic" and "radioactivity" frighten people because they sound mysterious and make them think of bombs or long-term destruction. This is inherited from the Second World War, the Cold War and, of course, also from severe (and regrettably avoidable) accidents (in particular Chernobyl, more than Fukushima). This image is propagated in film and other popular media, and it is an image that it is difficult to dispel. Some will say that this difficulty arises because this image is based on fact, but the problem is how the facts are presented. More people have suffered from other technologies than from nuclear energy - from the oil industry to chemical plants (it is no accident that the body of regulations that concern industrial safety in Belgium goes under the name SEVESO, the Italian town hit in 1976 by a very serious chemical plant accident that killed hundreds, and we should not forget Bhopal…). It sounds a little facetious to promote a technology by saying: "look, his technology killed more people than mine". Nevertheless, it is a fact that other technologies, potentially more dangerous than nuclear, are tacitly accepted because their benefits are taken for granted; or simply because the damage they cause is less conspicuous. Or perhaps it is because the risk related to them is seen to be controllable, while the nuclear risk is falsely perceived to be uncontrolled (another example of the ‘mystery’ that surrounds nuclear-related issues).

To address the second problem, R&D is required to find solutions that guarantee improved safety but also low construction prices, with simpler design, standardization, etc. Small modular reactors might be able to meet this goal better than large plants, but this debate is continuing.

Safety is a key issue when it comes to public acceptance of nuclear energy technology. What work is currently being done to increase operational safety in the sector and what further work is required?

A lot of work is being done, despite the very limited overall resources devoted to the issue. Passive safety is the main objective and is pursued especially in new designs. This means that a system is conceived in such a way that, in the event of an accident, it implements automatic safety controls (e.g. by spontaneously triggering emergency cooling of the reactor), without the need for any active human (or computer) intervention, by exploiting ineluctable physical laws (like gravity). The difficulty here is to make these systems affordable and compatible with plant availability. Other aspects addressed are: improved containment in the event of accidents, harmonized procedures for safety assessments (inspections, protocols for decisions…), etc. Furthermore, the lessons learned from previous accidents, like Fukushima, are always rapidly implemented to rule out similar situations in the future.

However, it is important to emphasise one aspect: safe design and efficient (passive) safety systems, or improved containment etc., not only prevent or limit the consequences of accidents, but also intervene when conditions that may result in an accident are produced. Severe accidents can almost invariably be ascribed to the failure of a material somewhere in the chain of events. Therefore, the use of superior-performance materials and the accurate prediction of the degradation they incur during operation (leading to the need for periodic replacement, etc.), is key to ensuring safety. Consequently, the development of innovative materials with better properties, as well as precise knowledge of what happens to materials in operation, i.e. progress in materials science, should be seen as pillars for nuclear, and indeed for general industrial safety.

Finally, no matter how safe a system is, it is always possible to increase its safety, so research and development in this direction are always needed. This means it is indispensable to have qualified scientists and technicians, able to maintain the scientific and technical excellence and know-how required to ensure increasingly higher safety standards. But if the corresponding technological sector is not promoted or offers unclear perspectives, it is difficult to ensure a generational turnover.

The safe disposal of nuclear waste is another issue that resonates with the public. What is being done to increase the safety of waste disposal and what role do nuclear materials play in waste management?

The issue of what to do with waste that may remain potentially dangerous for thousands of years is of course another point that contributes to the negative image of nuclear energy among the general public. Indeed, the immobilization of highly radioactive waste, to neutralise their radiotoxicity in long-term safe nuclear repositories, is an important problem. In order to fully demonstrate the long-term safety of disposal in geological formations, the related geochemical and physical processes are being studied in depth. Progress has been made in this direction: all results indicate that geological disposal has very low risk, remaining well below natural radiation levels. Finland and Sweden are close to deploying a geological repository. Here, materials and structural integrity have a role that is more or less central, depending on the waste management system. For geological disposal in rock the long-term integrity of the container is a key barrier, whereas for disposal in salt or clay the container is less relevant. The form of the waste is also an issue (spent fuel versus glass) that may play a role. So, yes, materials are fundamental in waste management also: every object is made of a given material and the selection of the most suitable one based on the detailed knowledge of its properties and behaviour is always important.

But there is also another aspect. Fast reactors, generally classified as 4^th generation (Gen IV) (those being built now are Gen III), offer the possibility of transmuting nuclear wastes, i.e. changing the nature of the atomic nuclei, making them less dangerous and shorter-lived. At the same time, Gen IV reactors produce more nuclear fuel than the fuel used (this sounds like the Philosopher's Stone, but it is true) and, by extending the period spent in the reactor core, they extract as much energy as possible (high burnup). Appropriate ways to recycle spent fuel would then allow the volumes of dangerous wastes to be reduced, while feeding fresh fuel to new reactor cores: hence the importance of fuel research also. Gen IV reactors adopting this "close fuel cycle" can thus reduce the amount of waste via transmutation and high burnup, while extending the possibility of running fission nuclear reactors for centuries to come. However, for Gen IV reactors to be built, suitable materials are needed that are more resistant to the effects of high temperatures and radiation than existing ones. They should also be compatible with coolants other than water. So, once again, targeted developments in materials science are key to more sustainable nuclear energy.

With regard to nuclear materials, what are currently the key research priorities to ensure that the nuclear sector has the advanced materials it needs to contribute to the safe and sustainable decarbonisation of the European energy sector?

There are two main issues both implying, in essence, a better understanding of the physical processes that concern materials:

• Developing continuously improved knowledge of the behaviour of materials under the conditions they face in the reactor, both in operation and in off-normal situations, so that the probability of failure can be minimised and design can be made increasingly safer;
• Developing new materials that offer superior capabilities, to make failure even less likely and design even safer, as well as more efficient.

The conditions faced by nuclear materials are generally quite extreme: over time they suffer from severe degradation that needs to be controlled. Therefore the study of the ageing of materials when subjected to prolonged irradiation in specific environments (temperature, coolant…) is crucial. This implies developing safe criteria to establish how long they can be used, based on materials testing, characterization and qualification in the correct environment, as well as on the development of relevant models, preferably with a solid physical background. Methods of inspection and protocols for safety assessments of each component also need to be established or improved. For example, there is a problem with the embrittlement of steels used for vessels in current reactors due to neutron irradiation, and with demonstrating that, despite this, current vessels can actually operate for up to 60 years (versus 40 up to now), without compromising safety, with obvious advantages in terms of economy and competitiveness. Steels used for in-core components, on the other hand, are simultaneously subjected to the effect of irradiation, mechanical load and contact with coolant, giving rise to complex phenomena that may lead to failure and that must therefore be anticipated and avoided, both for safety and economy. Materials in Gen IV reactors will face higher temperatures and significantly higher irradiation levels than current reactors, while using coolants other than water, e.g. gas or liquid metals. Consequently, they need to be qualified for those conditions, again via suitable testing (which is not obvious for liquid metals), characterisation, and the development of models, so as to arrive at suitable safe design criteria. For Gen IV reactors it is envisaged that innovative materials with superior performances need to be developed. These developments may also benefit current generation reactors, as well as fusion. One serious problem that we face is that facilities to expose materials to high levels of irradiation are in scarce supply worldwide, so it is becoming increasingly difficult to conduct comprehensive studies of this type.

Is there sufficient support at policy level for priority nuclear materials research? What more could be done to create the collaborative frameworks needed to ensure the optimal use of Europe’s resources and expertise?

Research on nuclear materials, both because of the extreme conditions that need to be reproduced in the laboratory and the infrastructure needed to handle radioactive materials, is very costly. Euratom funding for nuclear energy research in general, and consequently also nuclear materials, has remained more or less constant over the last 7 years and it is expected to remain the same, or become de facto somewhat less, over the next 7 years, while costs obviously keep increasing. The tendency in almost all Member States is to freeze or reduce funding in this field and the economic constraints Europe is facing don’t help. In the nuclear field we have been used to this scarcity of funding for many years, so we try to optimize as much as we can the use of available resources and to develop efficient collaborative frameworks. In that respect, we are probably "better trained" than other energy technologies. Increasingly better coordination and integration of research is the only solution, especially given that no single MS, not even France, can be completely self-sufficient, so European collaboration within an established framework is absolutely necessary. Within the Joint Programme on Nuclear Materials (JPNM), and more generally within the European Energy research Alliance (EERA), we are determined to further advance the sharing of resources and pooling of expertise, so as to show convincingly that we can work efficiently and that it is worth investing in us. We also need to make a special effort to retain our competence and train the next generation of scientists in a field that, because of the unclear perspectives offered, struggles to attract young people. Again, without a clear political willingness to appropriately fund research in this field, the possibility of progress seriously decreases and the scientific community involved in this research shrinks to a worrying level.

How important has the SET-Plan been as a framework to support the development and optimisation of nuclear energy systems and how closely aligned are the objectives of the Joint Programme on Nuclear Materials with the objectives for nuclear energy as identified in the SET-Plan?

The SET-Plan is an important framework highlighting the need to develop effective energy decarbonisation policies in Europe and to move towards a low-carbon energy economy. It is open to all energy technologies and promotes integration and fosters science. As such, it sets the basis for the further development and optimisation of nuclear energy systems. The JPNM has the objective of supporting the qualification and development of structural and clad materials as well as fuels. It also aims to ensure safety and long-term nuclear energy sustainability by improving our fundamental understanding of the response of materials when exposed to neutron irradiation, and to anticipate component ageing. These objectives are closely aligned with the objectives of the SET-Plan for nuclear energy for 2020 and 2050: "implementation of solutions for waste management" and "demonstrate the long term sustainability of fission generation IV technologies". However, sadly, to date the SET-Plan has not yet translated into tangible funding opportunities. We all hope, for the sake not only of nuclear energy, but for all low-carbon energy technology, that in the near future we can see the role of the SET-Plan materialise into targeted and sufficient funding for energy research.