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 currently proceeding at a fast pace with the design of the plant and its safety assessment. We have reviewed all of the key safety systems and identified some open technical issues that we are currently resolving.

A summary of the key results from 2019 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 2019 report.

Fractured zone and plant location

There are certain significant fractured zones in the bedrock at 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. The studies and investigations include previous studies, of which the first ones were conducted already in 2018, and studies on eight new topics. The studies include for example bedrock investigations in the plant area and assessments of observed land movements in Olkiluoto and in some Swedish nuclear power plants.

The conclusions state that the movements, if any at all, are insignificant in terms of nuclear safety and constructability. On the basis of all of the studies and investigations, Fennovoima considers the current plant location acceptable. However, we will monitor movements of the bedrock throughout the plant lifecycle. In addition, properties of the bedrock will be taken into account in the design of the buildings. We will continue discussions on this subject matter with the plant supplier in early 2020.

Principal evaluations

In early 2019, we established focus groups consisting of experts from different engineering disciplines to scrutinize concerns, challenges, and open issues related to plant-level design and the overall licensability of the plant. A summary of the key results of these evaluations is given below.

Layout evaluation for plant-level buildings

The evaluation focused especially on safety design features that could have a significant impact on layout and structural design of the plant. These include for example matters influencing the exterior dimensions of the power plant buildings, such as structural fire protection arrangements, radiation safety of access routes and facilities, and physical protection.

The assessment revealed deficiencies, for instance, in the realization of some system separation principles. In particular, the principles were not realized, or the realization of the principles was not clearly indicated by the design documents in the case of the control building. The evaluation also emphasized a need to comprehensively investigate the buildings and facilities where the separation principles cannot be realized by means of simple structural separation. The description of functional design in the design documents was not sufficiently detailed at this point to allow for a proper assessment of the support functions. This applied to the cooling and ventilation functions, in particular.

In addition to submitting the assessment results to the plant supplier and the general designer, we gave some concrete modification proposals and submitted some requests for clarification, some of which have already been taken into account in the plant design. We established a separate focus group that focuses on assessing the design of the control building. The plant level building evaluation was also an efficient means of clarifying Fennovoima’s internal basic design evaluation processes and criteria.

Reactor and primary circuit

The purpose of the evaluation was to create a fundamental understanding of the reactor and primary circuit as safety barriers. The evaluation was divided into two parts: the fuel and reactor core and the primary circuit were evaluated separately. According to the assessment results, critical open design issues involve, for instance, operating experience on fuel, in-core measurement, and the plant’s availability factor. A need to supplement or update some of the analyses and documents was also observed.

Radiation safety

With the evaluation, we aim to ensure that we have a clear understanding of all the matters influencing radiation safety in the plant. In addition, we identify any open issues related to plant design that should be changed or at least justified in more detail in the design. The work started in 2019 and will continue in 2020 with discussions with the plant supplier, followed by a presentation of the results to STUK.

Safety culture self-assessment

In early 2019, we carried out Fennovoima’s first safety culture self-assessment. The assessment method we used is based on the safety culture framework of the International Atomic Energy Agency (IAEA) and Fennovoima’s own safety culture principles.

Both development areas and strengths were identified with the self-assessment. The observed development areas included the need to clarify roles and responsibilities, to strengthen leadership for safety, and to improve cooperation and information flow within the organization. Identified strengths of the organization are the possibility to report observations and thus assist the organization in learning, opportunities linked to the Fennovoima Reprogrammed development program, good atmosphere at work, and support for employees in the development of their competencies.

On the basis of the results, we were able to determine that Fennovoima’s safety culture has somewhat improved since an independent assessment by VTT Technical Research Centre of Finland in 2017. VTT’s assessment stated that the level of Fennovoima’s safety culture is adequate. 

The development and assessment of the safety culture will continue throughout the lifecycle of the nuclear power plant. Changes do not take place overnight: they require time. The most important aspect is that the safety culture must not be merely empty words, but an integrated part of the organization’s daily operations and management.