Nuclear Energy: From Construction to Decommissioning of a Nuclear Installation

Nuclear energy holds a special position within the critical infrastructure system. Few other areas combine such a high degree of technological complexity, such a long facility life cycle, and the need for continuous monitoring of safety and resilience. Responsibility accompanies a nuclear installation from its construction and commissioning, through decades of operation, all the way to its decommissioning.

The exceptionally high safety requirements serve a fundamental purpose – to protect the life and health of the population and the environment, and to prevent events whose consequences could extend beyond the boundaries of the nuclear installation itself. It is precisely this perspective that is reflected in the Critical Infrastructure Act, which defines the entire life cycle of a nuclear installation as a single essential service.

Position of the service within the critical infrastructure system

Under Annex No. 1 to Act No. 367/2024 Coll. on Critical Infrastructure, this concerns:

Sector: Energy

Subsector: Nuclear energy

Category of entities: holders of a licence under a special regulation

Essential service: construction, commissioning, operation and decommissioning of a nuclear installation

Central authority: Ministry of Economy of the Slovak Republic

The Critical Infrastructure Association of the Slovak Republic has concluded a memorandum of cooperation with the Ministry of Economy of the SR as the central authority for this sector.

Why is this essential service important?

Nuclear energy occupies an exceptional position in Slovakia's energy mix. Nuclear power plants provide a substantial share of domestic electricity generation and represent a stable energy source that is not dependent on immediate weather conditions.

In the case of nuclear installations, however, the importance of the essential service cannot be assessed solely by the volume of electricity generated. Continuity of operation must always go hand in hand with nuclear safety and protection of the population.

Safety systems and measures are therefore designed both to prevent events from occurring and to minimise their consequences should they occur despite preventive measures. Preparedness also includes emergency plans, monitoring systems and procedures for cooperation between operators of nuclear installations and the relevant public authorities.

The resilience of nuclear energy is thus not merely a matter of the state's energy security. It is at the same time a matter of protecting the population and the environment.

Slovakia and nuclear energy – a few concrete facts

The importance of nuclear power for Slovak energy is well documented by data from Slovenské elektrárne. In 2024, its nuclear power plants generated 18,232 GWh of electricity, representing 87.71 % of the company's total electricity production.

A current example of the individual stages of a nuclear installation's life cycle is Unit 4 of the Mochovce Nuclear Power Plant. On 22 May 2026, the Nuclear Regulatory Authority of the SR issued a decision authorising its commissioning. After the decision became final, the loading of nuclear fuel into the reactor core began on 29 June 2026, moving the unit from the construction stage to the commissioning stage.

On 6 August 2026, the Unit 4 reactor reached first criticality – for the first time, a self-sustaining fission chain reaction was created and maintained in its core. In nuclear energy, the term "critical" does not denote a dangerous or emergency condition, but a precisely defined physical state required for the controlled start-up of a reactor.

Slovakia also has many years of experience with the opposite stage of the nuclear installation life cycle – decommissioning. The Jaslovské Bohunice site is an example of how nuclear safety and population protection requirements continue even after electricity generation has ended.

Slovak nuclear energy today therefore covers, in practice, several phases of the nuclear installation life cycle – operation, commissioning of a new unit, and decommissioning of shut-down facilities.

What risks need to be monitored?

A nuclear installation is a complex system whose safety and reliability depend on technologies, people, digital systems and external suppliers.

Significant risks include in particular:

• technological and operational failures, including failures of systems important to nuclear safety;
• cyberattacks against information, communication and industrial control systems;
• physical security threats and intentional acts;
• outages of external power supply and other supporting systems;
• disruption of supply chains, especially for specialised components, spare parts, materials, software and expert services;
• dependence on a limited number of qualified or certified suppliers;
• geopolitical and economic risks that may affect the availability of technologies and materials;
• a shortage of qualified experts and the loss of critical know-how;
• extreme meteorological and climatic phenomena;
• risks associated with the management of radioactive waste and spent nuclear fuel.

A distinctive feature of the nuclear sector is that risk assessment cannot focus solely on the probability of an event. Particular attention must also be paid to low-probability events with potentially severe consequences for the life and health of the population, the environment and the functioning of the state.

Supply chains – a risk that can begin far from the nuclear installation

In nuclear energy, a critical component, material or expert service may be provided by only a small number of qualified suppliers. A production outage, a geopolitical event, a logistics problem or a subcontractor's failure can therefore create risk thousands of kilometres away from the nuclear installation itself.

That is why it is not enough to know only the direct supplier. It is important to understand the entire supply chain, to identify its critical links, geographic concentration, ownership ties, dependence on a single manufacturer and the availability of alternative sources.

The ability to identify these dependencies in advance is precisely one of the prerequisites for the resilience of the nuclear sector.

The specific role of the Critical Infrastructure Association of the SR

AKI SR is building expert and analytical capacities focused on systematic monitoring of risks in critical infrastructure supply chains.

The aim is to identify critical suppliers and subcontractors, to track geographic and ownership ties, supply concentration, potential critical points of dependence – "single points of failure" – and geopolitical, economic or technological events that may affect the continuity of essential services.

For the association's members, such an analytical foundation should gradually deliver concrete outputs: early warnings of emerging risks, analyses of critical dependencies, risk assessment of supply chains, and support in exploring options for diversification and alternative suppliers.

At the same time, nuclear installations depend on the functioning of other sectors – energy, electronic communications, digital infrastructure, transport and water management. The association therefore also creates space for connecting entities from individual sectors, identifying cross-sector dependencies and preparing joint crisis scenarios.

This approach makes it possible to monitor risk not only within the boundaries of a single organisation or a single sector, but across the entire system of interconnected critical infrastructure.

Safety as a fundamental prerequisite

Nuclear energy clearly demonstrates that the resilience of critical infrastructure cannot be measured solely by the ability to keep a service running. It is equally important to ensure that the service is provided safely and that the protection of the life and health of the population remains a priority even in extraordinary and crisis situations.

The resilience of nuclear energy therefore rests on a combination of safe technologies, qualified people, reliable supply chains, preparedness for emergencies, and cooperation among all the entities on which its functioning depends.



In the next article in our series, we will continue with another essential service in the energy sector, gradually presenting the areas whose safe and reliable functioning is essential to the resilience of the Slovak Republic.