How a small nuclear power plant works
In the future, electricity and heat can be produced by small nuclear reactors (or small modular reactors, SMRs), either together or separately. A small nuclear power plant will produce emission-free energy steadily and reliably all year round. The small nuclear power plant is an umbrella term for a number of different types of plant, equivalent in size to a medium-sized industrial plant.
Structure of a heat-generating small nuclear power plant
1. The reactor module encloses the nuclear reactor.
2. Inside the nuclear reactor, fission reactions, occur in the heavy element nuclei of the nuclear fuel, which heat the water circulating through the reactor.
3. Passive safety systems do not require an external power grid or human response to operate. For example, reactor modules can be placed in a large pool of water that can cool them for up to a month in an emergency.
4. Thanks to other passive systems, many types of SMRs do not, for example, require pumps to circulate water in the primary circuit. The circulation of water is then achieved by gravity and by natural force.
5. The primary circuit is a closed pipe system in which water circulates between the nuclear reactor and the heat exchanger.
6. In heat exchangers, heat is transferred through the walls of the pipe into the water of the next water cycle. The heat exchangers isolate the different water circuits from each other, so that radioactive material is not transferred from the primary circuit to the intermediate circuit with the heat.
7. The intermediate circuit is the closed water circuit between the primary circuit and the district heating network.
8. The cooled return water from the district heating network is heated back above 90 degrees in the intermediate circuit heat exchanger. The heated district heating water is then directed to heat the buildings.
Combined heat and power with small nuclear power plants
Small nuclear power plants designed for electricity generation can produce electricity and heat through cogeneration. In this case, part of the hot water steam used for electricity production is diverted to heat production. This increases the overall efficiency of the small nuclear power plant.