expert-talks

Site characterisation, a crucial step, multiple expertises

Nuclear

Choosing a site to build a nuclear power plant is a highly complex and strategic issue that requires extensive studies to assess the safety, environmental impact and feasibility of the project. This essential site selection and characterisation phase requires a great deal of technical expertise.

A rigorous evaluation process

Any land development requires the acquisition and processing of precise geotechnical, geophysical and environmental data. This is more important when the construction is a nuclear power plant, a project of great complexity by nature: it is a matter of demonstrating to the regulatory authorities and the public that all the safety and environmental criteria have been correctly assessed and respected. The IAEA (International Atomic Energy Agency) has established a 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 earthquake zone or having water available nearby for cooling). The pre-selected sites are then subject to on-site studies, particularly concerning their geological structures. 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 studies, and to determine the design parameters of the power plant. “While some criteria are eliminatory, such as earthquakes or the unfeasibility of having an emergency plan, others are only deemed disqualifying and require additional studies to evaluate their potential risks and the 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 Dr. Arzu Altay,Project Director.

The characterisation studies not only ensure the most appropriate choice of site, but also contribute to select the right technology and impacts the technical design of the project. This allows to optimise cost and reduce turnaround times.

 

Assessments and impact studies

The challenge during the 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 normal 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 Dr. Arzu Altay.

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

  • Geoscience: topographical, geological, geophysical, geotechnical, hydrogeological and seismological studies to assess the suitability of the soils and subsoils;
  • Environment: meteorological, hydrological (marine and surface) and ecological studies (terrestrial and marine), air and noise modelings, hydrodynamic modeling and radiological dispersion modeling to assess hazards and environmental impacts;
  • Social: demographic and socio-economic studies; or related to external effects/accidents induced by man (aircraft crashes, fire, explosions…).

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

 

Mobilisation of multiple skills

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 and 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 surface with a very high level of accuracy. All these collected information –as maps, graphs, tables, lists, reports, etc.- in spatial and non-spatial data forms are digitilised for better traceability. They are structured and organised in a database, thus can be consulted by all teams, in real time and from anywhere as long as internet connection is available.

It is crucial to digitise all the data gathered from the site characterisation studies. To this end, Assystem has developed WebGIS, a specific software program capable of collecting a wide range of data, then having them analysed and interpreted by experts to develop scalable and adaptable field models” says Dr. Altay.

WebGIS software is a powerful asset for site characterisation missions. It’s a simple interface makes it possible to update, centralise and secure all the data collected on the sites. Each member of the project team can access the project data he or she needs, 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, it takes an average of three years to complete a full site characterisation before obtaining authorisation. In this respect, supporting new entrants to this market, who have no knowledge of nuclear energy or the conditions imposed by the regulator, is a real challenge, “which implies” notes Dr. Altay, developing a common understanding throughout the project in order to reach an agreement on the entire scope.

Valuable support throughout the project cycle

Characterising a site requires a very good understanding of the environment and the complex processes involved. 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 needs, to offer strategic and/or operational support tailored to the client’s needs – from the study of the sites to the obtaining of the permit 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. They offer environmental monitoring, support and compliance services.

In Saudi Arabia, for example, our teams helped select the site and prepare the licensing documentation for the first nuclear power plant. Among their missions: the realisation of a complete characterisation and evaluation study of the sites; the delivery of a detailed evaluation of the sites according to predefined exclusion criteria of the IAEA. They also prepared site information 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 define the design for the Akkuyu nuclear power plant in Turkey. This phase helped the client to determine the specific parameters required for the design of the nuclear power plant.

 

About the expert

Arzu Altay

Project director in the entity in charge of providing site assessment and site characterisation services

Dr. Arzu Altay is an engineer with doctorate degree, project director in the entity in charge of providing site assessment and site characterisation services. Since 2011, she has worked on the selection, site characterisation and licensing of two plants in Turkey (Akkuyu and Sinop) and a third one in Saudi Arabia.