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.

Safety of the Hanhikivi 1 nuclear power plant is ensured during the design phase. Our reviews on the systems and buildings are significant in terms of safety have been systematic and comprehensive. The reviews ensure that the plant is safe and fulfills the requirements. A summary of the key results from 2021 can be found below. 

Safety evaluations 

Fennovoima’s own safety evaluations can be divided into four groups: system safety evaluation, layout safety and design, principal evaluations, and the licensee’s safety assessment. 

System safety evaluation 

We finalized the system reviews of the Hanhikivi 1 nuclear power plant at the beginning of 2022. We performed a separate system safety evaluation for each system, indicating the status of pre-defined key factors. In practice, the system design’s safety is proven, and there are no significant open questions in the design that would require major design alterations at a later stage. We continue solving the open items. 

Layout safety and design 

Layout safety and design evaluations based on PSAR building descriptions were finalized during 2021. We evaluated each safety classified building and structure separately, indicating the status of pre-defined key factors. To conclude, there are no such open safety items that would necessitate significant changes in the layout. The majority of the open items have already been solved during 2021, and the work will be finalized in 2022.

Principal evaluations 

Plant level evaluations are an essential part of the licensee’s safety assessment. Fennovoima has performed plant level safety evaluations for selected important topics: 

  • Reactor and primary circuit principal evaluation 
  • Containment functional evaluation 
  • Functional defense-in-depth and diversity evaluation 
  • Evaluation of protection against internal and external hazards 
  • Radiation safety principal evaluation 
  • I&C plant level evaluation 
  • Design basis threat evaluation 

We follow up systematically on the open items raised in the principal evaluations and ensure timely resolving of those. Also STUK reviews the assessments and their results. 

Licensee’s safety assessment 

The licensee’s safety assessment is part of the construction license documentation. It summarizes Fennovoima’s plant safety assessment and is compiled mainly on work we have carried out when reviewing the basic design and PSAR. The assessment includes plant-wide evaluations, system and building safety evaluations, and summaries of their justifications. 

We drafted the first version of the document in fall 2021. That version included and highlighted several open issues, primarily due to missing justifications of design solutions. We have updated the document as we have proceeded with the PSAR review, and plant-wide evaluations have evolved. We will finalize the safety assessment when the PSAR review and plant-wide evaluations are complete.

Instrumentation & Control 

We evaluated the I&C architecture and systems at the end of 2021. Evaluations were based on pre-defined key factors and included I&C plant level evaluation and separate system safety evaluations for I&C systems. We will continue solving the open items in 2022. 

Fennovoima’s own safety analyses

Deterministic Safety Analysis 

We ensure with the deterministic safety analyses that the Hanhikivi 1 nuclear power plant fulfills its safety mission and that its structures, systems, and components effectively keep releases of radioactive materials below acceptable limits.

RAOS Project worked on a summary of deterministic analyses during 2021. We approved the documentation by the end of the year and submitted it to STUK for review. Some of these analyses were delivered to STUK for the first time. These include analyses of severe accidents and containment analyses, as well as Fennovoima’s summary of radiation dose assessments. 

We also continued to perform our comparative analyses of the plant supplier’s analyses and our own deterministic analyses and submitted a summary of these to STUK. The most important purpose of these analyses is to support the licensee's safety assessment. 

Probabilistic Risk Assessment 

Probabilistic risk assessment is a systematic and comprehensive method for assessing the risks associated with external and internal threats and the probabilities and effects of transient events. We received an updated probabilistic risk assessment documentation and design phase model from RAOS Project at the end of October 2021. We began reviewing it and will complete it in early 2022.

Failure Tolerance Analyses 

Failure tolerance means that the system meets safety requirements and functions properly, even if some of its components are damaged. We received an updated failure tolerance analysis material and model from the RAOS Project for review at the end of October 2021. We will finalize the review in early 2022. 

Hazard Analyses 

With the help of hazard analyses, we evaluate how different threats would affect the operation and safety of the Hanhikivi 1 plant. We use them to ensure that internal and external threats to safety and electricity generation are fully taken into account in plant design. 

We received updated hazard analyses from RAOS Project in the fall and mainly completed the review during 2021. The analyses show that the facility tolerates a wide variety of threats. We also identified some areas for improvement in the documentation of results and the scope of analyses. Solving the remaining open points and comparing the results of the analyses with the plant design will continue in 2022. 

Radiation Safety 

We have submitted the documentation related to radioactive waste management and radiation protection and received STUK’s decision on those. Also development and review of release source terms and assessment of radiation doses to the public caused by transient and accident situations continued in 2021. 

Furthermore, the radiological environment baseline study continued in 2021, according to the study program. We updated the program schedule and included the interim spent fuel storage in the program. We delivered the 6th revision of the program to STUK in December 2021. At the Hanhikivi 1 project site, the meteorological measurement system and the automated environmental radiation monitoring system have been installed and taken into use. 

Latest update on March 16, 2022.