Nuclear newbuild – large and small reactors

As nuclear power’s advantages in achieving climate targets have become more widely recognised, several European countries are planning for or continuing their newbuild programs. Such countries include, e.g., France, UK, Hungary, Slovakia, Poland, Czech Republic, Romania and Bulgaria. 

Large reactors that are available on the market today can be considered evolution of the light water reactors currently in operation around the world. The power output of the currently available large reactors is approximately in the range of 1000-1600 MW. For comparison, the Olkiluoto 3 reactor in Finland has as much as 1600 MW.

The large nuclear power plant units that have been commissioned recently or that are currently under construction or in planning are often called Generation III or Generation III+ designs to distinguish them from the earlier generation of designs that were constructed in the 1970s and 1980s. Comparing to Gen II designs, Gen III/III+ designs have enhanced safety features. Some Gen III+ designs also utilise passive safety features in an extended way. 

While small modular reactors may have received a lot of attention recently, so far almost all of the ongoing newbuild construction projects and most of the projects in advanced stages of planning are for large, gigawatt-scale nuclear power plants. 

The advantages of large-scale nuclear power plants include in-build economy of scale and proven technology with reference plants that are already in operation. Also, even if there have been cost overruns and construction delays in the projects, important lessons have been learned that can be valuable for improving future projects. On the other hand, the anticipated long construction times for large units and the significant size of the one-time investments can have an impact on the financing of the projects. 

Nuclear power plants with a power output of less than approximately 300 MW are called small modular reactors (SMR). In some of the plant designs, the power plant is a combination of multiple reactor units. SMRs differ from large reactors not only in their lower power output but also because they are modularised and can be more easily serially produced, i.e. installed from prefabricated modules.

SMRs can offer flexibility and can be installed closer to urban and industrial areas, enabling co-generation of district and industrial heat. Small modular reactors can bring new solutions also for district heating production. 

The smaller capacity, however, doesn’t affect the quality of the plant: in terms of technology and safety requirements, small modular reactors are comparable to large nuclear power plants. Standardised solutions and serial production enable cost and time savings. These savings are realised when multiple power plants are made. 
 

The current country-specific differences in the regulatory requirements for plant licensing impact the deployment of small modular reactors. Prefabrication in a factory requires standardised structures and systems. In order for the same solution to be used in different countries, either the regulatory requirements have to be standardised or the solution that is approved in one country must be applicable also in another country.  

Leveraging the opportunities of small modular reactors still requires close collaboration  between plant suppliers, energy producers and authorities at a national and international level.