Advanced Nuclear Energy Systems
Addressing the Climate Crisis with Nuclear Technologies
The urgency of the environmental and climate crisis demands transformative changes in energy usage and supply. Key strategies identified by the European Union and the International Energy Agency (IEA) for achieving climate neutrality by 2050 include:
- Increasing Energy Efficiency: Reducing overall energy consumption by improving efficiency in end-use applications.
- Decarbonizing the Primary Sector: Transitioning from fossil fuels to low-carbon energy sources in energy production.
- Restructuring End-Use Energy: Electrification of transportation and industry sectors.
- Capturing Greenhouse Gases: Implementing technologies to remove greenhouse gases from the atmosphere.
A crucial step in this process is ensuring an adequate supply of low-carbon electrical energy. The International Energy Agency (IEA) estimates that to meet climate goals by 2050, the global supply of electrical energy needs to triple. Integrating diverse technologies, each with their own strengths and limitations, is essential for building a sustainable energy future.
Nuclear power stands out as the most reliable source of low-carbon energy. It currently ranks as the second largest source of low-carbon energy worldwide, after hydropower. Unlike intermittent renewables such as wind and solar, nuclear power plants provides a stable and continuous supply of energy, making it the surest path to fossil free future. The role of nuclear power is expected to grow, with the IEA projecting a doubling of nuclear generation capacity by 2050. Nuclear power plants will also be required to provide additional energy services traditionally handled by fossil fuel plants, such as primary and secondary regulation, heat, and hydrogen supply.
Small Modular Reactors: The Key to a Decarbonized Energy Future
Small reactors are an important complement to large conventional units and address not only the engineering challenges but also the economic ones, by providing a different financing structure and affordability for smaller companies, due to a lower absolute cost. The abbreviation SMR in narrower sense refers to small modular reactors—reactors under 300 MW, whose design is modular. This means they can be manufactured in a factory and then transported to the site for assembly in modules. By design, they can be almost any derivative of the conventional water cooled or advanced Generation IV reactors. Special group of SMRs are micro modular reactors (MMRs). These are reactors with a capacity of under 10 MW. The concept is resembling large diesel generators—nuclear batteries that arrive on-site nearly fully assembled and ready for use in a plug-and-play manner. They are intended for use in industrial energy applications, and for use in remote areas such as mines and isolated locations in Alaska and Siberia.
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Summarized, SMRs facilitate decarbonization of Diverse Energy Sectors: I. Load-following Operation → Replacing Coal & Gas Plants II. High-temperature Heat Supply → Industrial Applications III. Synthetic Fuels → Transport Additionally, SMRs allow: Use of Advanced Nuclear Fuels → Entering Circular Economy New Business Models → Industry Investors & Sector Coupling |
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Research Activities at the LTE
Advanced nuclear technologies differ significantly from conventional nuclear power plants (NPPs). Notably, individual components of the primary circuit are typically integrated within the reactor vessel. Novel heat exchangers, such as compact plate (NUWARD) and helicoil steam generators (NuScale), along with extended heat pipes (eVinci), are being used. Passive systems for the removal of residual heat are frequently embedded in the primary system. Some reactors even use new types of nuclear fuel such as mixed oxide fuel (MOX) and tri-structural isotropic particle fuel (TRISO) in form of pallets or balls. So advanced reactors are not just distinct in terms of size and power but also in the fundamental components of the plant, reactor coolants and reactor fuels. Due to these differences, such reactors also exhibit unique characteristics in terms of thermo-hydraulics (and reactor kinetics).
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Scheme of advance MMR with Heat Pipes (source: eVinci, Westinghouse) |
Given the significant differences in design and operation of advanced reactors as compared to conventional nuclear power plants, the validity of existing system codes is challenged, making it crucial to develop new approaches in system modelling. Many of the forementioned characteristics are beyond the calibration scope of established codes like RELAP5, ATHLET, APROS, or TRACE. This necessitates the innovation of novel models that can accurately predict the performance of advanced reactors under various operational conditions, including transient and accident scenarios. Development of integral system codes is thus enabling the use of nuclear in diverse energy services, while upholding rigorous safety standards. |
At the Laboratory for Heat and Power we are cooperaitnig in development of constitutive models to support the safety demonstration of SMRs. The research is ongoing in cooperation with the Institute of Nuclear Technology and Energy Systems ("Institut für Kernenergetik und Energiesysteme", IKE) at the University of Stuttgart and the Reactor Engineering Division at the "Jozef Stefan" Institute.
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European Industrial Alliance on SMRs
The alliance aims to facilitate and accelerate the development, demonstration, and deployment of the first SMRs projects in Europe in the early 2030s. It operates through specific working groups to improve enabling conditions for SMRs development, demonstration and deployment including the revitalisation of the nuclear supply chain. Its activities aim to support specific SMR projects and accelerate their deployment on the European market.
The Faculty of Mechanical Engineering at the University of Ljubljana (UL FME) remains committed to advancing Small Modular Reactor (SMR) technology through our educational, research, and professional efforts. UL FME is a member of the Alliance since its founding general assembly in May 2024. It is active in Technical working group TGW2: Technology and R&D&I, with focus on the two subgroups: Safety demonstration R&D and Non-electrical applications.
The Laboratory for Heat and Power is the main coordinator of the activities at the UL FME. The representatives in the general assembly and technical working groups are prof. dr. Mihael Sekavčnik (Official representative) and Mihael Boštjan Končar (Deputy).
We are also connecting with other Slovenian stake holders within the SMR STEPS platform (SMR STakeholder Engagement Project for Slovenia).
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Publications
Selected publications:
- Challenges in Modelling of Passive Heat Removal Systems for Small and Micro Modular Reactors
Mihael Boštjan Končar (UL FME), Jörg Starflinger (IKE), Mihael Sekavčnik (UL FME), Mitja Uršič (JSI)
In: Nuclear Energy for New Europe 2024, International Conference Proceedings, Portorož 09–12 Sep 2024.
Mihael Boštjan Končar (UL FME), Mihael Sekavčnik (UL FME), Igor Kuštrin (UL FME), Gordan Janković (Krško NPP)
In: International Youth Conference on Energy, Proceedings, Colmar, 02–06 Jul 2024.
Pia Fackovič Volčanjk (UL FME, GEN), Andrej Senegačnik (UL FME)
In: Nuclear Energy for New Europe 2023, International Conference Proceedings, Portorož 11–14 Sep 2023.
Contact
Mihael Boštjan Končar (MihaelBostjan.Koncar@fs.uni-lj.si, personal page)
prof. dr. Mihael Sekavčnik (Mihael.Sekavcnik@fs.uni-lj.si, personal page)