Anita Collaboration at Uppsala University details how small modular reactors are expected to permanently change perceptions of nuclear energy.
Interest in nuclear power generation as a low-emission and dispatchable energy source has increased significantly in recent years due to inherent technical issues associated with the significant expansion of weather-dependent electricity production.
For example, with the closure of nuclear reactors, countries such as Sweden and Germany have created increasingly unstable and vulnerable power systems where reduced transmit capacity, increased network costs, volatile and negative electricity prices are part of today’s reality.
So, for what reason does nuclear power provide technically attractive solutions to these problems?
First, let’s make sure that all traditional energy sources are based on the forces that hold atoms and molecules together, while nuclear power is based on the forces that hold atoms together.
Why nuclear power?
Nuclear power is much stronger than nuclear power. For example, when two oxygen atoms bond to a carbon atom, the reactor fuel nuclear reaction releases about 50 million times more energy than is released in combustion.
This has dramatic results. Excluding geothermal energy, nuclear power generation has the lowest carbon dioxide per KWH. This is generated in terms of the life cycle of all available technologies1.
The physical footprint of nuclear power per kWh generated is minimal, so the invasion into the environment is small. Furthermore, concrete, aluminum and steel materials flow is the smallest of all energy technologies2. Furthermore, nuclear power generation occurs at 24-7, with heavy generators acting as efficient stabilizers for the electric grid. The reactor can also be located in a strategic location within the power grid, minimizing wiring costs.
Therefore, nuclear power has some technically attractive properties, but there are also real and perceived problems. Perceived problems are often difficult to identify as they often involve subjective feelings about nuclear technology, but the actual problems can be summarised by:
New large reactors are costly investments, with few stakeholders actually having the economic capacity to invest in nuclear reactors. On the other hand, the depreciation period for nuclear reactors is around 20 years. That is, after this period, the reactor can generate useful energy at an additional 60 or perhaps even 80 years of age at a commercially viable price. A long-term perspective creates paradoxically problems as it creates immeasurable political risks. This risk includes the possibility that cooperative politics may choose to eliminate investment prerequisites, for example, for ideological reasons. Managing spent nuclear fuel is a complex effort. The issues involved here do not arise primarily from technical considerations, but rather relate to a variety of regulatory aspects. Already comprehensive regulations on safety, safeguards and security tend to get even more complicated and intrusive over time. The constant risk of a large breakdown of technology systems is a nuclear issue for three reasons. The first reason is a significant economic loss for nuclear reactor owners. The second reason is that a critical part of electricity production collapses, which has a negative impact on society. The third reason is that there is a risk of radioactive material spreading around.
The first reason is difficult to address, but the second reason can be improved by building more units and creating redundancy. The third can be improved by installing various mitigation systems that occur in the event of a major accident, ensuring that the surroundings are essentially not affected by events.
Such systems have been modified in all current Generation II reactors in Sweden and are standard equipment for Generation III and III+ reactors.
Standardization of small modular reactors
Small modular reactors (SMRs) are gaining interest in addressing large investment costs and increasing the flexibility of nuclear power in energy systems. SMR is the set name of the spectra of various technologies that have electrical power outputs typically below about 300 mW. SMRs may be of the so-called Generation IV type, or they may use the same technology as current large reactors: light water, as coolant/moderators.
The SMR is intended to be built in the factory as a completed unit or as part of a factory, and in both cases it will be installed on-site. An important part of the concept of SMR is that, unlike today, when each reactor is individually approved, the reactor should be approved for each type.
The fact that SMR is standardized, has a relatively small physical footprint and is installed rather than built rather than on-site, is expected to reduce capital requirements to a level where new stakeholders, such as current nuclear companies and cities, may take the above mentioned political risks.
In particular, the idea of standardization is important, and historical experience supports the importance of producing nuclear reactors in a uniform structure. For example, within 13 years, Sweden was able to connect 12 fairly standardized reactors to the grid. In this situation, the learning curve will be steep. This is important when implementing new technologies quickly and efficiently.
Finally, please note that SMR has good sales experience and has been operating on military ships for about 70 years. Therefore, optical water SMR can be considered as a developed version of a nuclear reactor for a military vessel that meets civil requirements.
SMR Applications
Electricity production
Due to the relatively low power output, SMR is less suitable for national power generation than full-scale reactors. However, its size and modular construction make it ideal for local or local power generation. For example, it produces electricity for large communities and industrial facilities.
It is also suitable for reinforcement and stabilizing the country’s electricity grid when needed, but the economic impact of this application is currently unknown.
In countries with no power grids in large countries, SMR could be an efficient solution to the power shortages that these countries often suffer. During operation, SMRs are also not expected to require a large workforce. This also suggests that this concept can benefit the poor part of the world at present.
Production beyond electricity
In addition to the above benefits, the strength of SMR lies in applications that currently lack environmental and climate-friendly solutions. Examples of such applications include district heating, seawater desalination, greenhouse heating, process steam and hydrogen production.
Anita Collaboration provides comprehensive research into how SMR can be used in a variety of applications. For example, this paper provides a brief description of the subject3.
SMR Safety and Security
Several technical features of SMR are based on simple physical principles. This allows the safety system to be “passive”, thus achieving a high level of safety. In other words, no human intervention or external force is required to make them work.
For example, the relatively small reactor core size allows for reactor vessel design, such as by using self-circulating coolant to allow cooling of damped heat in a reactor shut down. Additionally, such systems can be made simple to minimize valves and other factors that can break down.
Overall, this significantly reduces the risk of core meltdown, as external power or handling is not required to operate the coolant pump. Here, it should be noted that passive systems have already been added to very safe structures based on long-term experience from nuclear design and utilization.4.
In some applications, SMR can be expected to become part of a distributed system with many units. This provides an opportunity to create redundancy in the energy supply, but also creates challenges. One such challenge is the management of nuclear material. Today’s non-proliferation regime includes the nuclear protection regime as an important tool to enable all nuclear materials to be determined in the place where they are envisioned and have declared properties.
However, current safeguards are developed to handle a relatively small number of full-scale nuclear reactors in the country, with logistics and storage being well defined and easy to manage from a protection standpoint.
Things become more complicated when many SMRs are introduced into non-traditional nuclear sites. For example, new transport routes for fresh and spent fuels will be required, and in these cases, the implementation of a wider range of safeguards will be required. In general, logistics are more diverse and more difficult to monitor in a comprehensive way.
Current nuclear protection measures are not fully adapted to such new reality, and novel approaches need to be developed. This will require close cooperation between regulatory authorities, industry, academia and the International Atomic Energy Agency (IAEA). Such development work is currently underway in Anita Collaboration 55.
Finally, for land-based use, it is important to note that the size of the SMR allows them to be installed underground or rocky caves, reducing exposure to external influences and thus enhancing security.
summary
At the fully implemented stage, small modular reactors are expected to provide economically viable solutions for small to medium-sized applications. This situation makes the technology suitable for small stakeholders, such as cities, businesses, and others who need to produce useful energy in cities and regions.
The safety of the various SMR concepts currently under scrutiny is designed to meet the strictest possible requirements. One important safety feature is the ability to cool the core after shutdown using self-circulation if necessary.
While typical SMRs’ electricity production is considerably smaller than full-scale nuclear reactors, SMRs show several important benefits for a variety of applications other than electricity production.
The relatively small size allows SMRs to be deployed in places where full-scale nuclear reactors are not physically compatible. Such locations may be close to cities or factory areas. The combination of heat and electricity creates SMRs that are interested in combining district heating and electricity production, so if the reactor operates in a loaded mode, the economy improves. The electrical output is smaller than full-scale EActors, but the 300 MW generator is by no means small in terms of inertia. This means that SMR is suitable for stabilizing the grid at strategically selected points. At the basic level, photowater SMR does not represent new technology. In addition to the passive safety system, the operation and maintenance scheme will be a reduced version of the version used in current photowater reactors. This is advantageous as it allows for significant use of existing know-how and logistics. However, new, anticipated applications pose several new regulatory issues, safeguards and security challenges, and these aspects must be addressed appropriately.
reference
See https://group.vattenfall.com/siteassets/corporate/who-we-are/sustainability/doc/life-clecy-assessments-for-vattenfalls-electicity-generation_2023.pdf. (2021) 105200 https://www.uu.se/download/18.547e7b518eeffced3d71e9/1713515478959/c_10624222-l_3-k_anita-a1-rapport-1.pdf https://www.innovationnewsnetwork.com/smr-designs-suitable-for-swedens-electricity-production-needs/49733/ anita – uppsala University (uu.se)
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