What makes a good nuclear site?
When planning for a new nuclear power plant, one of the first big decisions is the selection of the plant site where one or several reactor units could be located. Final site selection is preceded by site survey (site screening) and followed by other important decisions such as site-specific inputs to the plant design (site characterization), freezing of the site layout (foreseeable production needs) and application for site-related permits (operational limits). In this way, the selected site will support safe and economic production over the life cycle.
There is a great variety of factors and requirements to be considered when selecting the preferred site: everything from natural phenomena and human activities to socioeconomic factors and nature conservation. This may feel very complex, however, the key decision-making perspectives for nuclear operations on a specific site can be comprised to the following key criteria:
1. Safety of public and environment: Potential influences on people and environment are shown to be excluded or insignificant.
2. Plant design for external events: Plant safety case and design envelope cover relevant external hazards and threats including site-specific impacts.
3. Enabling construction: Efficient plant construction is enabled by the ground properties, site area, infrastructure and local community.
4. Ensuring operation: Safe and economic production is ensured by feasible cooling, transmission, logistic and other necessary connections.
Under each of these four criteria, there are many specific factors to be evaluated. Figure 1 presents an overview without being fully exhaustive for a specific site.
Figure 1. Key decision criteria and related evaluation factors – just click the image to enlarge the view.
Some of the site-related factors are crucial already in the site screening process that aims to find possible sites for nuclear operations. These factors may trigger specific exclusion criteria related, among other things, to such geological properties or cooling problematics for which safe and feasible engineering solutions cannot be found. The so-called discretionary criteria, in their turn, are used to find candidate sites. These can then be ranked to select a preferred site as well as a reserve site that could be reconsidered in case something negative showed up later on when characterizing the preferred site. Exclusionary and discretionary criteria are defined project-specifically to focus the attention on specific factors important for site selection and corresponding engineering solutions.
The quality of the full site evaluation process and preparation for decision-making has a long-reaching influence on the safety and economy of a new plant. Monitoring of the different factors will continue throughout the construction and operation of the plant to ensure safety even in highly improbable events, paying attention also to any new information concerning site conditions and surrounding activities. Thus, the importance of the different site selection factors needs to be well understood so that the efforts can be efficiently prioritized and focused at each stage of the process.
The development of nuclear technology is bringing new aspects to site selection because the industry is striving towards standardized reactor designs. Due to this, many SMR suppliers want to avoid needs for site-specific design adaptation, which is why they aim at robust design envelopes for external hazard protection and geotechnical design. Furthermore, we can expect to see also nuclear-driven production of hydrogen, heat, water and synthetic fuels, which will affect site decisions through the evaluation factors shown in Figure 1. The key decision criteria, however, can be expected to remain unchanged. This also applies to situations where one or several SMR units are planned to be located in the vicinity of an area where the energy output would be directly utilized.
At Kind Atom, our experience tells us that the complexity of site-related issues can be managed when the related considerations are taken seriously from the very beginning of a nuclear new-build opportunity. Potential showstoppers need to be screened out first, and then one can optimize the site selection and the related plant design provisions to enable high plant safety and performance level in all potential conditions. By focusing the attention on key decision criteria and related evaluation factors, clearly justified decisions can be made for the combination of the selected site and the proposed technology.
Blog by Janne Liuko
Janne is the technology advisor of Kind Atom. He advises our customers in plant safety, production performance and economy over the investment lifecycle.