Nuclear safety

Nuclear technology and safety culture go hand in hand in ensuring the safety of a nuclear power plant. While confirming the safety by technical design, we also develop of our safety culture in compliance with the shared safety principles established for the project.

Plant safety is ensured in the design phase before construction of the power plant begins. We are proceeding with the design of the plant and its safety assessment.

A summary of the key results from 2020 can be found below. Our progress in solving the issues identified in the preliminary safety assessment of STUK (Radiation and Nuclear Safety Authority in Finland) is discussed in the Fennovoima´s year 2020 report.

Key safety assessments

We have assessed the plant’s systems and layout design systematically from the safety perspective, taking into account nuclear, radiation and occupational safety. Through our assessments, we ensure that the plant will be safe and that all the requirements set for it will be met. The most important assessments are summarized below.

Layout safety and design

We started the layout safety and design evaluation at the end of 2019. We are reviewing the layout against 31 assessment criteria. The criteria are associated with the following assessment areas: safety functions’ allocation and classification, protection against hazards, ambient conditions, radiation safety, security and safeguards, operation, maintenance, availability and occupational safety, design integrity, fire safety and rescue, civil design, layout and architectural design, decommissioning and radioactive waste management.

In 2020, we evaluated the buildings that are critical or have a considerable significance to safety. In addition, we assessed those buildings and structures that are important for the operability of the plant. The evaluation was carried out based on the available first review stage basic design documentation, the plant’s 3D model, concept-level documentation and technical architectures. Our central observations concerning nuclear and radiation safety were related to the reactor building, safety building, auxiliary building and one of the diesel generator buildings. The control building was excluded from the evaluation at this time, because its design was incomplete.

We shared our observations to the plant supplier. We will carry out the evaluation again once the basic design documentation, the plant’s 3D model and the building descriptions of the preliminary safety analysis report have been completed and delivered to us. We will use the layout safety and design evaluation in the licensee’s safety assessment, which is a part of the licensing documentation required for the construction license.

System safety evaluation

During 2020, we assessed the plant’s systems from the safety perspective. We have completed the first review stage for nearly all systems, apart from the I&C systems. In 2020, we conditionally approved the systems regarding frontline safety features and diverse safety features, and turbine systems. We submitted the related documentation to the Finnish Radiation and Nuclear Safety Authority for review and approval.

Significant safety improvements

The control building was completely redesigned in 2020. This provided clearer separation of the safety systems and protection against external and internal hazards. The design of the control building now includes a structurally isolated protective shell that ensures the functioning of the systems and the control room in the event of a large commercial airplane crash. In addition, the systems are clearly separated in accordance with the separation principle.

Fractured zone and the plant location

There are significant fracture zones in the bedrock of the Hanhikivi nuclear power plant site. Possible slow movements of the bedrock due to land uplift after the last ice age and movements caused by seismic events in the fracture zones have been comprehensively studied since 2018. The conclusions of the studies state that the movements, if any, are insignificant in terms of nuclear safety and constructability.

Geological studies carried out in 2020 did not alter the earlier picture of the geological conditions of the area, but they refined it.

The current position of the plant on the Hanhikivi peninsula is safe and functional on the basis of all of the studies and investigations. We will monitor movements of the bedrock in the plant area throughout the plant’s lifecycle in accordance with a monitoring program. In addition, the properties of the bedrock will be taken into account in the design of the buildings. The matter of the fracture zones and the positioning of the plant on the site will be discussed in the preliminary safety assessment.