Safety
Our alternatives consist solely of safe plants and the solutions associated with them. Throughout the entire project, we work in close cooperation with the Finnish Radiation and Nuclear Safety Authority to ensure that we meet all requirements set for a nuclear facility.
Our safety principles
Our safety principles are based on the principles set out in Finnish nuclear safety standards:
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Multiple layers of protection (several independent safety barriers)
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Prevention and preparedness
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Operator’s responsibility for safety in all situations
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Openness and transparency in regulatory activities
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Continuous improvement – we continuously observe our operations and strive to improve in all areas
Safety features of the reactor
The SMR reactors we are evaluating are small, modular nuclear reactors designed with simplicity, passive safety, and the minimisation of severe accident risks at their core. Many of their safety functions rely on natural physical principles—such as gravity and natural circulation—and do not require external power supply or operator actions. These reactors are subject to the same safety requirements as large-scale reactors, and they must be able to withstand, for example, an impact equivalent to that of a passenger aircraft.
In SMR reactors, the safety systems function without electricity or active pumps.
The reactor shuts down and cools automatically, for example in the event of a power outage or other disturbance.
Key features:
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Natural circulation of water for cooling
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Gravity‑based emergency water systems
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Automatic reduction of reactor power as temperature rises
The lower power output of SMR reactors means they generate less residual heat than large reactors. This makes cooling the reactor core easier in accident scenarios.
Benefits:
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Cooling is technically simpler
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Lower probability of severe accidents
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More limited potential impact area
In many SMR designs, the reactor core, steam generators and pressure vessel are located within a single integrated unit.
Benefits:
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Fewer pipes and connections
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Reduced risk of leakage
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Simplified monitoring and maintenance
Many SMR concepts are installed partially or entirely below ground.
Advantages:
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Better protection against external hazards (e.g., weather events, impacts)
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Inherent radiation shielding
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Improved safety in abnormal or emergency situations
The fuel and reactor geometry are designed so that the chain reaction naturally decreases as the temperature rises.
Benefits:
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Negative reactivity feedback coefficients
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Long refuelling intervals reduce operational risks
Independent oversight – the cornerstone of Finnish nuclear safety
In Finland, nuclear safety oversight is internationally respected and exceptionally strict. Its purpose is to protect people, the environment, and society from the harmful effects of radiation at every stage of nuclear energy use.
Radiation and Nuclear Safety Authority (STUK) – the supervisory authority
Nuclear safety oversight is carried out by the Radiation and Nuclear Safety Authority (STUK), an independent national authority. STUK supervises the safety of nuclear facilities, the use of radiation, and the control of nuclear materials throughout their entire lifecycle.
STUK’s responsibilities include:
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Defining and overseeing safety requirements for nuclear facilities
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Evaluating licence applications and safety assessments
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Conducting inspections and testing at facilities
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Radiation and environmental monitoring
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Preparedness for abnormal and emergency situations
Licensing process and continuous oversight
The construction and operation of nuclear facilities require multiple licences, issued by the Finnish Government and Parliament. At every stage, STUK evaluates whether the facilities meet strict safety requirements.
Oversight does not end when the operating licence is granted, it continues throughout the entire lifetime of the facility, including:
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Regular inspections
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Monitoring of safety reports
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Approval of modifications before commissioning
Preparedness for emergency situations
Finnish nuclear operators work closely with international organisations, such as:
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International Atomic Energy Agency (IAEA)
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Nuclear safety authorities of the European Union
Finland’s system is regularly evaluated through international peer reviews.
At Helen Nuclear Ltd, safety is the fundamental starting point in all situations. Preparedness for the use of nuclear energy is based on legislation, regulatory requirements, and careful advance planning. The aim is to protect people, the environment, and society under all circumstances.
Helen Nuclear Ltd prepares for crisis and emergency situations already during the planning and development phases of its operations. Safety is comprehensively integrated into technical solutions, operating models, and the organisation’s overall preparedness.
Preparedness covers, among other things:
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technical disturbances and equipment failures
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external events such as severe weather conditions and infrastructure disruptions
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societal emergency situations
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serious accident scenarios
Regulatory oversight of nuclear safety in Finland is independent and led by public authorities. Helen Nuclear Ltd works in close cooperation with the Radiation and Nuclear Safety Authority (STUK) and other authorities throughout all phases of its operations.
Regulatory oversight includes:
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assessment of safety requirements
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approval of preparedness and emergency response plans
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monitoring of drills and readiness arrangements
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continuous supervision of overall safety performance
Helen Nuclear Ltd has established plans for managing disturbance and emergency situations. The operating procedures are based on clear allocation of responsibilities, trained personnel, and predefined processes.
Key principles include:
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rapid identification of situations
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clear decision‑making and leadership structures
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safety as the primary objective
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close cooperation with authorities and other stakeholders
Preparedness is maintained and further developed through regular exercises and evaluations. These exercises test both technical systems and the organisation’s operational capability in different scenarios.
Lessons learned and observations are used to improve practices, ensuring that operations are continuously updated to meet evolving requirements and changes in the operating environment.
In abnormal or emergency situations, timely and reliable communication is a critical part of safety. Helen Ydinvoima Oy is committed to transparent communication in cooperation with the authorities. The objectives of communication are to:
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provide clear and accurate information
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support the communication of authorities
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strengthen trust and improve public understanding