NUCLEAR SITING: A KEY MILESTONE BEFORE DESIGN AND CONSTRUCTION

The IAEA (International Atomic Energy Agency) has developed guidelines for siting process based on strict safety standards. The first phase involves identifying candidate sites based on a certain number of exclusion criteria (for example, not being located in an active earthquake zone or having water available nearby for cooling). The pre-selected sites are then submitted to on-site studies, with a particular focus on their geological structures, environmental and social impacts, seismicity characteristics and safety assessments. Once the choice of the site has been made, the characterisation phase begins. 

The objective at this stage is twofold: to further evaluate the site by conducting in-depth site-specific studies, and to determine the design parameters of the power plant.

“While some criteria are classified as exclusionary, such as massive landslide, existence of surface ruptures (seismic faults) and/or volcanic activities, massive liquefaction, karstification or the unfeasibility of implementation of the emergency plan, the others are only deemed to be discretionary and require additional studies to evaluate their potential risks and the engineering solutions to be implemented. The goal is to see if these solutions are feasible in technical terms and achievable in terms of cost – and without major environmental impact”, says Gizem Özden, Director of Business Development for Environmental and Siting Services. 

The site characterisation studies not only ensure the most appropriate choice of site, but also contribute to the selection of the right technology and impact the technical design of the project. This allows the optimisation of cost and the reduction of time-to-completion of the project.

Assessments and impact studies

The challenge during the site characterisation phase is to anticipate, reduce and manage project-related risks (which may be linked to climatic hazards, soil type, specific environmental requirements, etc.). This is why numerous fields of data are observed and collected and are the subject of regular assessment reports to ensure full compliance throughout the life of the project.  

“One of the important criteria checked is generally the radiological impact, which, based on dispersion studies, makes it possible to define emergency zones in case of unusual operation and potential accidents. Another crucial study is the thermal dispersion, with a consequent rise in water temperature that could significantly affect marine life, and which determines the design of the cooling chain”, emphasises Gizem Özden. 

More generally, three categories of assessment studies are carried out: 

• Geoscience: topographical, geological, geophysical, geotechnical, hydrogeological, and seismological studies to assess the suitability of the site conditions. 

• Environment: meteorological, hydrological, oceanographical, ecological studies (terrestrial and marine), air and noise modelling, hydrodynamic modelling and radiological dispersion modelling to assess hazards and environmental impacts. 

• Social: demographic and socio-economic studies; or related to external human induced effects/accidents such as aircraft crashes, fire, explosion, etc.

Site characterisation requires a wide range of services, particularly in the environmental and geoscience fields, which Assystem is able to completely address.

Mobilisation of multiple skill-sets 

The scope of the fields observed during the site characterisation phase calls for a wide range of expertise and engineer profiles in: geology, geophysics, geohazards, topography, meteorology, hydrogeology, environment, seismology, civil, nuclear engineering, etc. In addition to the diversified skills of the teams, the collection of information requires cutting-edge equipment, such as laser remote sensing or LIDAR, a remote measurement technique carried on board of an aircraft, which scans surfaces with a very high level of accuracy. All this collected information –as maps, graphs, tables, lists, reports, etc.- in spatial and non-spatial data forms are digitalised for better traceability. They are structured and organised in a database, and can therefore be consulted by all teams, in real time and from anywhere as long as an internet connection is available. 

“It is crucial to digitise all the data gathered from the siting studies. To this end, Assystem has developed WebGIS, a specific software capable of visualising and presenting a wide range of physical and environmental data in GIS* environment. This capability facilitates the creation of scalable and adaptable analyses and models, by making the data easily accessible to engineers and experts.”  

* Geographic Information System 

WebGIS software is a powerful asset for site characterisation missions. It is a simple interface which makes it possible to update, centralise and secure all the data collected on sites by keeping spatial information. Each member of the project team can access any project data they need, generate images and maps by using the data, and monitor the overall progress of the project. 

While the schedule depends on the country’s degree of maturity in nuclear installations, it takes an average of three years to complete a full site characterisation before obtaining authorisation. To this end, supporting new entrants to this market, who have no prior knowledge of nuclear energy or the conditions imposed by the regulator, is a real challenge, which implies developing a common understanding throughout the project in order to reach an agreement on the entire scope, notes Gizem Özden.  

Valuable support throughout the project cycle

Characterising a site requires an excellent understanding of the environment and the complex processes involved in a nuclear project. A technology-independent engineering company like Assystem, which has a very strong safety and compliance culture and is recognised for its experience in this pre-construction phase, is a major asset. 

In practice, Assystem’s teams are able to intervene on all or part of the requirements, to offer strategic and/or operational support tailored to the client’s needs – from the selection and characterisation of the sites to the obtention of permits and the supply of the preparatory elements for construction, anywhere in the world. In addition to this expertise, Assystem’s teams can also support their clients to manage all environmental risks and to identify and implement sustainable solutions to their projects. Assystem also offers environmental monitoring, support, and compliance services. 

In Saudi Arabia, Assystem teams conducted site characterisation studies with consideration of all the aspects to provide the licensing documents for the first nuclear power plant in the country. Among their missions: the realisation of a chttps://www.assystem.com/en/references/monitoring-surveys-for-the-construction-of-a-nuclear-power-plant/omplete characterisation and evaluation study of the predetermined two sites; and the delivery of a detailed evaluation of the sites according to the IAEA recommendations, as well as local regulations and requirements. They also prepared site information package for the technology providers to accurately develop the plant design. 

In Uzbekistan, Assystem was asked to support the energy transition program launched by the country. Within this framework, the team of experts has elaborated and provided a preliminary safety report (PSR), in order to advise the local agency on the choice of a site for the development of a nuclear energy program. 

In Turkey, our teams performed the necessary site investigations including detailed geological, geophysical and geotechnical studies, hydrogeological testing, seismic hazard assessment studies, to characterise the site conditions for the Akkuyu nuclear power plant. This phase helped the client to determine the specific parameters required for the design of the nuclear power plant. In addition, our team in Turkey conducted baseline environmental surveys and prepared the ESIA (environmental and social impact assessment) report for a future nuclear power plant in Sinop.