Inspections at the Loviisa nuclear power plant

STUK carries out inspections to oversee the operation and use of the Loviisa nuclear power plant. The periodic inspection programme covers safety management, main operational processes, procedures and technical acceptability of systems.

STUK draws up a plan for the inspection, setting out the subject of the inspection and any preparatory actions required of the licence holder. The result of the inspection and the resulting requirements are set out in the inspection report.

Periodic inspections

Below are summaries of the inspections carried out by STUK in year 2025 in accordance with the periodic inspection programme for the Loviisa nuclear power plant.

Utilisation of the PRA, 2 June and 4 June 2025

The inspection focused on the preparation of the nuclear power plant’s Probabilistic Risk Assessment (PRA) and the procedures related to its application as well as the utilisation of PRA in the safety management of the nuclear power plant. At Loviisa 1 and 2 and the spent fuel storage, the inspection covered the following:

• Status of PRA models and applications
• Extensions and updates under preparation and their schedules
• Organisation, resources, guidelines related to PRA preparation
• Timeliness of external threat assessment
• The role of PRA in plant safety improvements.

Based on the inspection, there have been no significant changes in Fortum’s PRA resources, and no comments were given on personnel competence management. The PRA guidelines are up to date, the PRA has been developed as planned, and the PRA is used in a versatile manner to support safety management. The update of the seismic PRA will continue at least in 2025, and studies on other external threats are under way, of which strong winds may become an increasingly significant phenomenon. Fortum does not see the risk of oil spills as significant despite recent changes in the Gulf of Finland’s conditions, as the old PRA analysis was conservative. The seawater-independent cooling towers introduced in 2015 have also significantly reduced the significance of the oil spill risk.

The PRA is used in many ways in the design and evaluation of plant safety improvements. In recent years, there have been few purely PRA-based improvements, but improvements may have been implemented in connection with other plant modification projects, in which case PRA experts are involved in the early stages of the projects and can influence planning. Otherwise, the way in which a PRA-based plant modification proceeds will depend on the extent of the change and how it is detected. The current PRA guidelines do not fully describe the actual range of alternative procedures. STUK considers the systematisation of procedures to be useful.

Based on the inspection, Fortum’s procedures for utilising PRA comply with set regulations. STUK issued no requirements based on the inspection findings.

Human factor engineering in design, 3–4 June 2025

The inspection looked into how human factors engineering (HFE) was taken into consideration in design activities.

In 2023, Fortum prepared an HFE programme. The expectation level set by this programme must be integrated into Fortum’s existing design and plant modification implementation procedures. This work has already been carried out, and the HFE programme’s approaches will be applied to new plant modifications. There is still limited experience of application.

Based on the inspection, Fortum has the resources and competence for HFE tasks, but there is a need to examine the more extensive development of the organisation’s competence and reporting on HFE activities (including the assessment of the current state of the plant from the HFE perspectives). STUK issued one requirement to the aforementioned matters.

Plant maintenance, 26–27 May 2025

The aim of the inspection was to verify that the licensee will ensure the functional capacity of the Loviisa 1 and 2 units in the short and long term. The selected inspection topics were used to assess that the resources and functions related to condition monitoring and maintenance as well as the instructions and tasks related to these were adequate to ensure the safe use of the plant units in design-based operating and environmental conditions.

The inspection verified, such things as, the maintenance procedure of the institution database, the adequacy of resources for ageing management and quality control, and the long-term planning of annual maintenance. In addition, assessments and reports related to the usability and maintenance of the residual heat removal (RHR) system and the backup RHR system used for residual heat removal completed.

Fortum’s maintenance and ageing management procedures and resources were found to comply with set regulations. The condition of the residual heat removal systems was found to be good during the inspection, but attention should be paid to the management of spare parts with regard to some obsolete spare parts items.

STUK issued no requirements on the basis of the inspection.

Emergency response arrangements, 1–2 April 2025

The aspects verified in the inspection focusing on emergency response arrangements included the situation of training provided for the emergency response organisation, automated environmental radiological monitoring, meteorological measurements and procedures for preparing dispersion forecasts. The equipment and arrangements at Keilahti Emergency Response Centre were also verified in connection with the inspection.

The inspection found that Fortum has developed the emergency response activities actively and in smooth cooperation with the authorities. Fortum’s emergency arrangements were found to comply with the company’s plans and meet STUK’s requirements. STUK issued one requirement based on the inspection findings that concerned the response time of radiation safety experts assigned to the emergency response organisation in emergency situations. STUK required that Fortum update the relevant instructions, ensuring that the planned response time can be reliably achieved.

Radiation protection, 8–9 April 2025

The radiation protection inspection conducted in 2025 focused on the dosimetry service at Loviisa power plant and on measuring workers' radiation doses.

The inspection included a pre-announced test conducted by STUK, in which a small number of dosimeters were exposed to different radiation doses in STUK’s metrology laboratory. The dose determinations carried out by Loviisa dosimetry service met the criteria set for the test.

Based on the inspection findings, Fortum’s dosimetry service is compliant with the statutes, and workers' radiation doses are determined to a high standard. STUK issued one requirement based on the inspection findings. An internal organisational change in radiation protection at Loviisa power plant took place in March 2025, in connection with which some of the persons responsible for the dosimetry service were replaced. Fortum was required to describe the changes to the dosimetry service organisation and submit them to STUK for information.

Safety functions, 23–24 April 2025

The inspection of safety functions had a particular focus on the containment building and serious accident management. On this inspection, the containment buildings' hydrogen management systems, the spray system outside the containment building and the electrical systems needed to manage serious accidents were examined.

The inspection found that the serious accident management systems are compliant with the requirements. The inspection discovered no significant shortcomings in the instructions, resources or procedures for operating experience feedback relating to them. STUK issued one requirement based on the inspection findings requiring Fortum to investigate the testing procedure of the containment building spray system after heat exchanger service.

Information security, 23–24 April 2025

The inspection comprised an independent assessment of Loviisa power plant’s information security management system, information security risk management and information security management in supplier relations and supply chains.

The inspection found that information security management at Loviisa power plant is appropriate and compliant with the applicable statutes. STUK issued no requirements based on the inspection findings.

Nuclear safeguards, 28–29 April 2025

STUK’s inspection focused on the nuclear safeguards system at Fortum’s Loviisa power plant to determine how Fortum fulfils its nuclear safeguard obligations. The main topic of the inspection was Fortum’s procedures for dismantling other nuclear material and official notifications relating to it, as well as procedures associated with IAEA and Euratom monitoring equipment and control seals at the plant.

The inspection found that Fortum's procedures regarding dismantling notifications and monitoring equipment are appropriate. STUK paid attention to recent improvement in communication between teams as well as waste management and storage. According to STUK’s observations, marking of the monitoring equipment at the plant could be improved, and obstacles hindering monitoring equipment operation could be identified better.

STUK issued one requirement based on the inspection findings, requiring Fortum to update the basic technical data of the plant with descriptions of difficult-to-reach storage locations.

Realisation of undefined OLC repair times, 22 January 2025

The inspection assessed the monitoring and implementation of work that requires operational limits at the Loviisa nuclear power plant. The inspection focussed especially on so-called X work, referring to work for which no limit period has been specified in the Operational Limits and Conditions (OLC).

The inspection found that Fortum has comprehensive procedures for monitoring X work. The work and their risk significance are regularly assessed in various meetings and reports. In the job management system, the X work classification is also used for work not within the scope of OLC. In STUK’s view, it would be better to restrict X work to only refer to work requiring operational limits specified in the OLC and establish another classification for non-OLC work. STUK presented an observation on the subject in the inspection report.

Based on the indicators presented by Fortum, the duration of work requiring operational limits in accordance with the permitted 3-day repair period has been significantly reduced in recent years. However, there are no corresponding indicators for other limit categories, which makes it difficult to monitor their duration. STUK estimates that creating such indicators could further improve operations and ensure the coverage of positive development.

In assessing the risk caused by work that requires operational limits, Fortum uses different priority measures to prioritise critical work. X work is monitored in the same way as other work requiring operational limits, and the risk analysis covers their effects. STUK estimates that a more detailed analysis of the distribution of X work into different systems could help further develop practices.

The inspection did not result in any requirements presented by STUK.

Chemistry, 12–14 March 2025

The inspection focused on monitoring the water chemistry conditions and activity levels of the primary and secondary circuits of units 1 and 2 of the Loviisa nuclear power plant. The inspection supervised the appropriateness of the laboratory equipment and facilities used for monitoring. The inspection included a verification of sampling at the plant and reviewed the chemistry organisation.

Based on the inspection, the chemistry organisation is able to adequately respond to the plant’s analysis needs and required development tasks. The laboratory located in the controlled area has been extended, but the deployment of the facilities is still ongoing. STUK made an observation regarding the qualification requirements of the substitute in charge of the safety function of the chemistry area described in the plant’s rules of procedure, taking into account in particular water chemistry control competence.

The inspection did not result in any requirements presented by STUK.