Name: Temelin Nuclear Power Plant: Technical Profile and Operational History
Address: CZ

Overview

The Temelín Nuclear Power Station stands as the largest and most technologically advanced nuclear facility in the Czech Republic. Located in the municipality of Temelín in the South Bohemian Region, the plant is situated approximately 60 kilometers southwest of Prague. It plays a critical role in the Central European energy mix, providing a significant portion of the country's baseload power. The facility is owned and operated by the ČEZ Group, the national energy conglomerate that dominates the Czech electricity market. As of 2026, the plant remains fully operational, contributing to energy security and carbon emission reductions across the region.

The plant consists of two pressurized water reactors (PWRs), each with a net electrical capacity of approximately 1,000 MW, bringing the total installed capacity to around 2,000 MW. This makes Temelín the single largest source of nuclear generation in the Czech Republic. The reactors are of the VVER-1000/V380 type, a design developed by the Russian engineering firm Atomstroyexport. This specific variant incorporates advanced safety features compared to earlier Soviet-era designs, including a reinforced containment building and improved seismic resistance. The choice of this technology reflects the Czech Republic's strategic decision to leverage proven Russian nuclear engineering while integrating Western safety standards during the construction phase.

Background: The decision to build a nuclear plant in Temelín was driven by the need to replace aging units at the nearby Dukovany plant and to diversify the Czech energy matrix. The site was selected for its geological stability and proximity to the Vltava River, which provides essential cooling water.

Construction of the Temelín plant began in the mid-1980s but faced significant interruptions due to the political and economic transitions in the Czech Republic following the fall of the Iron Curtain. Work resumed in earnest in the late 1990s, with the first unit achieving criticality in 1999 and the second in 2000. The plant was officially commissioned in 2000, marking a milestone in post-communist Czech infrastructure development. The project involved a complex blend of Russian technology and Western engineering oversight, particularly from French and German firms, to meet the rigorous standards required for entry into the European Union.

The operational status of Temelín has been characterized by high availability and relatively stable output. The plant employs approximately 1,000 workers on-site, making it a major local employer in the South Bohemian region. The presence of the plant has also spurred local economic activity, with the adjacent Vysoký Hrádek castle serving as an information center and tourist attraction, helping to integrate the facility into the local community. The plant's operation is closely monitored by the Czech Office for Nuclear Safety (ÚJZ), which ensures compliance with national and international safety regulations.

Environmental and social impacts have been subjects of ongoing discussion. Proponents highlight the plant's contribution to reducing greenhouse gas emissions, with Temelín preventing the release of several million tons of CO₂ annually compared to coal-fired alternatives. Critics, however, have pointed to issues such as thermal pollution of the Vltava River and the management of nuclear waste. The plant uses a combination of cooling towers and direct river discharge to manage heat output, a method that has been optimized over the years to minimize ecological disruption. The long-term storage of spent fuel remains a key challenge, with plans for a central repository still under development.

The Temelín Nuclear Power Station continues to be a cornerstone of Czech energy policy. Its operational efficiency and capacity make it indispensable for maintaining grid stability, especially as the country integrates more variable renewable energy sources like wind and solar. The plant's future is closely tied to broader European energy trends, including the potential for extended lifespans and the introduction of small modular reactors (SMRs) in subsequent phases. As the Czech Republic navigates its energy transition, Temelín remains a vital asset, balancing reliability, cost-effectiveness, and environmental considerations.

History and Construction

The development of the Temelín Nuclear Power Station represents one of the most significant infrastructure projects in post-communist Central Europe. The initiative to construct a new nuclear facility in the Czech Republic gained momentum in the late 1980s, driven by the need to diversify energy sources and reduce dependence on imported oil and lignite. Initial site selection processes evaluated several locations, but Temelín, situated in the South Bohemian Region near the confluence of the Otava and Lužnice rivers, was chosen for its geological stability and proximity to the main transmission grid. The decision to proceed with construction was formalized in the early 1990s, following the political transition after the Velvet Revolution, which brought both new investment opportunities and heightened public scrutiny regarding nuclear safety.

Construction of the first two units began in 1987, though significant delays occurred due to economic fluctuations and the transition from a planned to a market economy. The project was primarily financed by the state-owned utility ČEZ Group, with additional funding from the European Bank for Reconstruction and Development (EBRD) and the European Investment Bank (EIB). The reactor technology selected was the VVER-1000, a pressurized water reactor (PWR) design developed by the Russian state nuclear energy corporation Rosatom. This choice reflected the existing technical expertise in the region and the availability of supply chains from the former Soviet Union.

Background: The VVER-1000 reactors at Temelín are among the most modern of their type in operation, featuring advanced safety systems including a double containment structure and a diverse backup power supply, which were key selling points during the licensing process.

The construction phase was marked by several milestones and challenges. The first concrete for Unit 1 was poured in 1987, and for Unit 2 in 1988. However, the project faced interruptions in the early 1990s due to budget constraints and the need to align with emerging European safety standards. The licensing process was particularly rigorous, involving extensive reviews by the Czech Nuclear Regulatory Authority and international experts from the International Atomic Energy Agency (IAEA). Public opinion was mixed, with local communities concerned about the potential impact on the surrounding landscape and the safety of the nearby population.

Unit 1 achieved criticality in 1999 and was officially commissioned in 2000, marking a significant step towards energy independence for the Czech Republic. Unit 2 followed suit, achieving criticality in 2001 and commissioning in 2002. The total installed capacity of the two units is approximately 2,000 MW, making Temelín a crucial component of the country's baseload power generation. The project was completed within a relatively short timeframe compared to other nuclear projects in Europe, largely due to the use of standardized designs and efficient project management practices.

The completion of Temelín had a profound impact on the Czech energy sector. It helped to stabilize electricity prices and reduced the country's carbon footprint by displacing lignite-fired power plants. The plant also created around 1,000 jobs in the local area, boosting the economy of South Bohemia. The adjacent Vysoký Hrádek Castle was repurposed as an information center, serving as a hub for public engagement and education about nuclear energy. This initiative aimed to foster transparency and build trust with the local community, which had been skeptical of the project in its early stages.

Despite its successes, the Temelín project was not without controversy. Environmental groups raised concerns about the thermal impact on the Otava River and the potential for radioactive emissions. Critics also pointed to the long-term waste management strategy, which had yet to be fully resolved at the time of commissioning. However, the plant's operational performance has largely addressed these concerns, with consistent output and a strong safety record. The Temelín Nuclear Power Station stands as a testament to the feasibility of large-scale nuclear projects in a transitioning economy, balancing technical innovation with economic and social considerations.

Technical Specifications

The Temelín Nuclear Power Station is equipped with two VVER-1000/V380 pressurized water reactors (PWRs), a design developed by the Russian State Atomic Energy Corporation, Rosatom. Each unit provides a net electrical capacity of approximately 990 MW, resulting in a total installed capacity of roughly 2,000 MW for the station, per ČEZ Group operational data. The VVER-1000 design is characterized by a hexagonal active core containing 163 fuel assemblies, housed within a cylindrical stainless steel pressure vessel. The primary coolant system operates at a pressure of approximately 15.75 MPa, with a mean temperature of 302°C, transferring heat to four secondary steam generators per unit.

The secondary side of the thermodynamic cycle utilizes single-flow, double-reheat turbine generators. Each turbine drives a synchronous generator with a capacity of 600 MVA and an output voltage of 20 kV. The steam parameters entering the high-pressure turbine are approximately 6.0 MPa at 300°C, expanding through the stages before being reheated and passing through the intermediate and low-pressure turbines. This configuration allows for a thermal efficiency of around 36% to 38%, which is typical for large-scale PWRs of this generation. The generators are air-cooled and connected to step-up transformers that elevate the voltage to 400 kV for integration into the Czechoslovakia-Central Europe grid interconnection.

Cooling Systems and Condensers

Cooling is provided by a mixed system utilizing both the Lužnice River and a cooling tower. The primary heat sink is the Lužnice River, which flows through the site, providing makeup water and direct cooling for the condensers. A natural-draft hyperbolic cooling tower, with a height of 140 meters and a base diameter of 110 meters, serves as a supplementary cooling source, particularly during periods of low river flow or high ambient temperatures. The condensers are surface-type, using river water to condense the exhaust steam from the low-pressure turbines. The total cooling water flow rate is approximately 2,300 cubic meters per minute per unit, depending on the seasonal temperature of the river.

Caveat: The VVER-1000/V380 design at Temelín includes specific safety enhancements compared to earlier Soviet-era units, including a double containment structure and a diverse set of safety injection systems to mitigate the risk of large-break loss-of-coolant accidents (LBLOCA).

The safety systems are designed to handle a maximum design basis accident (DBA) with a core temperature rise not exceeding 250°C. The primary containment is a double-shell structure, with an inner cylindrical steel shell and an outer concrete dome, providing redundancy against leakage and pressure buildup. The station also features a diverse safety injection system, combining low-pressure and high-pressure injection pumps to ensure core cooling under various operating conditions. The electrical power supply for critical safety systems is provided by four 600 V AC buses, fed by two turbine-driven generators and two diesel generators, ensuring redundancy in case of a station blackout.

Parameter	Value (per Unit)
Reactor Type	VVER-1000/V380 PWR
Net Electrical Capacity	~990 MW
Gross Electrical Capacity	~1,020 MW
Thermal Power	2,970 MW
Primary Pressure	15.75 MPa
Mean Coolant Temperature	302°C
Turbine Generators	Single-flow, double-reheat
Generator Capacity	600 MVA
Cooling Tower Height	140 m
Primary Containment	Double-shell (Steel/Concrete)

The fuel cycle for the VVER-1000 reactors typically involves a 12-month outage for fuel shuffling, with a core loading of approximately 163 fuel assemblies. The fuel is enriched to around 3.8% to 4.2% U-235, with a burnup of approximately 45,000 MWd/tU. The station's design life is 40 years, with the potential for extension to 60 years based on periodic safety review reports. The technical specifications are subject to continuous monitoring and adjustment to optimize performance and safety margins, reflecting the operational experience gained since commissioning.

How does the VVER-1000 reactor design work?

The Temelín Nuclear Power Station utilizes the VVER-1000 reactor design, a specific variant of the Pressurized Water Reactor (PWR) technology developed in the former Soviet Union. As of 2026, the plant operates four such units, contributing to its total installed capacity of approximately 2000 MW, per ČEZ Group reports. The fundamental principle of a PWR involves using water as both the coolant and the neutron moderator. In the primary circuit, water is pumped through the reactor core, where it absorbs heat generated by the fission of uranium-235 atoms. This water is kept under high pressure—typically around 155 bars—to prevent it from boiling despite reaching temperatures of roughly 300°C. The heated water then flows into steam generators, where it transfers its thermal energy to a secondary water loop, producing steam that drives the turbine generators. The primary water returns to the reactor, completing the cycle, while the secondary steam condenses back into water after passing through the turbines.

The VVER-1000 design incorporates several distinctive features that differentiate it from Western PWRs, such as the Westinghouse or Areva models. One key characteristic is the reactor pressure vessel, which is a cylindrical steel container housing the active core, control rods, and the primary coolant. The VVER-1000 core typically consists of 171 fuel assemblies arranged in a hexagonal lattice, a layout that optimizes neutron flux distribution and fuel utilization. The control rods, made primarily of boron carbide, are inserted from the bottom of the core, which is a structural choice that influences the speed and mechanism of reactor shutdown. This bottom-entry design requires robust drive mechanisms to overcome the buoyancy and hydraulic forces acting on the rods during insertion.

Did you know: The VVER-1000 reactors at Temelín were among the first of their kind to be certified for operation in the European Union, requiring extensive safety upgrades to meet Western regulatory standards.

Safety mechanisms in the VVER-1000 are multi-layered, designed to handle both normal operational fluctuations and potential accident scenarios. The primary safety system includes the emergency core cooling system (ECCS), which injects borated water into the reactor vessel to absorb neutrons and remove decay heat if the primary coolant pressure drops. The containment building, a large steel or concrete shell surrounding the primary circuit, serves as the final barrier to prevent radioactive release into the environment. At Temelín, the containment structure is a combination of a steel sphere and a concrete outer shell, providing both pressure retention and shielding. Additionally, the plant features a diverse range of safety injectors and heat exchangers to ensure redundancy and diversity in cooling capabilities.

The operation of the VVER-1000 relies on precise control of the neutron population within the core. This is achieved through the movement of control rods and the adjustment of the boron concentration in the primary coolant. Boron acts as a chemical shim, absorbing neutrons to fine-tune the reactor's reactivity over longer time scales, while the control rods provide rapid response for immediate power adjustments or shutdowns. The reactor's thermal-hydraulic behavior is carefully monitored to ensure that the fuel cladding remains within temperature limits, preventing oxidation and potential failure. The design also includes a pressurizer, a separate vessel connected to the primary loop, which maintains the system pressure by heating or cooling the water, thus controlling the boiling point and ensuring stable steam generation in the secondary circuit.

Maintenance and operational efficiency are critical aspects of the VVER-1000's performance. The fuel assemblies are typically replaced in cycles of 12 to 18 months, with about one-third of the core being renewed in each outage. This refueling strategy helps to flatten the power distribution across the core, reducing thermal stresses on the fuel rods and the reactor vessel. The plant's instrumentation and control systems monitor thousands of parameters, including temperature, pressure, flow rate, and neutron flux, providing operators with real-time data to optimize performance and ensure safety. The integration of digital control systems in later upgrades has enhanced the responsiveness and reliability of these monitoring functions, allowing for more precise management of the reactor's thermal output.

Operational Performance and Fuel Cycle

Temelín has established itself as a cornerstone of the Czech Republic's baseload power generation since its full commercial operation began in 2000. The plant, operated by the ČEZ Group, consists of two pressurized water reactors (PWRs) with a combined net electrical capacity of approximately 2,000 MW. This output accounts for a significant share of the nation's total electricity production, often contributing between 20% and 30% of the national mix depending on hydrological conditions and maintenance schedules. The operational history of the site has been marked by high availability, with individual units frequently achieving capacity factors exceeding 85% in recent years. This level of performance is critical for grid stability in Central Europe, providing a steady counterbalance to the variability of renewable sources and the intermittent nature of neighboring coal-fired stations.

The fuel cycle for Temelín is managed through a combination of domestic enrichment capabilities and international supplier contracts. The reactors utilize low-enriched uranium, typically with an enrichment level of around 4.2% to 4.5% U-235. Fuel assemblies are supplied by major global vendors, including Westinghouse and Areva (now part of Orano), ensuring a diversified supply chain that mitigates geopolitical risks. The choice of fuel design is optimized for the specific thermal-hydraulic characteristics of the VVER-1000 technology adapted for the Temelín units. Each core loading cycle generally lasts 18 months, during which approximately one-third of the fuel assemblies are replaced. This refueling strategy balances the need for high neutron flux in the center of the core with the gradual burnup of outer rings, maximizing the energy extracted from each tonne of uranium oxide.

Waste Management and Decommissioning Strategy

Radiological waste management at Temelín follows a tiered approach, distinguishing between low-and-intermediate level waste (LILW) and high-level waste (HLW). LILW, which includes contaminated clothing, tools, and resins, is compacted and stored in concrete casks within on-site facilities. The volume of this waste is relatively small compared to the total output of the plant but requires long-term monitoring due to the presence of isotopes such as Cobalt-60 and Cesium-137. High-level waste, primarily consisting of spent fuel assemblies, is initially stored in the plant's pool storage facility, where water provides both cooling and shielding. As the pool reaches capacity, dry cask storage becomes the primary interim solution, allowing for flexible expansion of storage space on the site footprint.

Background: The Czech Republic has been developing a multi-stage strategy for the final disposal of nuclear waste. Temelín's spent fuel is currently considered part of the national inventory destined for a deep geological repository, with the Bohunice site identified as a leading candidate for the final repository location.

The long-term strategy for Temelín involves the gradual transition from pool storage to dry cask storage, which offers greater flexibility and safety margins for extended periods. This transition is critical as the plant approaches the middle of its design life. Decommissioning plans are already in the financial and technical pipeline, with provisions made in the electricity tariff structure to fund the eventual shutdown and site restoration. The adjacent Vysoký Hrádek castle, which serves as an information center, plays a role in public engagement, helping to contextualize the plant's operational transparency and waste management practices for local communities and visitors. This integration of historical and industrial elements underscores the plant's embeddedness in the regional landscape.

Operational performance at Temelín is also influenced by the broader European energy market dynamics. Fluctuations in carbon pricing and natural gas prices can affect the economic dispatch of the nuclear units, although their low marginal cost generally keeps them running at high utilization rates. The plant's ability to maintain high capacity factors is a testament to the robustness of the VVER-1000 design and the operational expertise of the ČEZ Group. As the Czech energy sector continues to diversify, Temelín remains a critical asset, providing not only electricity but also strategic reserve capacity and grid inertia. The ongoing focus on maintenance, fuel optimization, and waste management ensures that the plant can continue to contribute to energy security well into the next decade.

What are the environmental and safety impacts of Temelin?

Temelín’s environmental footprint is defined by its location on the Lužnice River, which serves as the primary heat sink for the two VVER-1000 pressurized water reactors. The plant discharges approximately 1,500 cubic meters of cooling water per second, raising the river’s temperature by roughly 5 to 6 degrees Celsius during peak summer operation. This thermal discharge is carefully monitored to ensure that aquatic ecosystems, particularly fish populations like the pike-perch, remain within tolerance limits. Water quality is maintained through a combination of natural dilution and mechanical filtration, with the Lužnice’s relatively high flow rate acting as a natural buffer against excessive thermal stratification.

Radiation Monitoring and Public Health

Radiation levels around the Temelín site are continuously tracked by the Czech Office for Nuclear Safety (ÚJŘ) and the Czech Hydrometeorological Institute. Under normal operating conditions, the annual effective dose to the average resident in the immediate vicinity is approximately 0.2 to 0.5 millisieverts (mSv). This figure is comparable to the natural background radiation in the South Bohemian region, which averages around 2.5 mSv per year. The plant releases both gaseous and liquid effluents, primarily consisting of tritium and carbon-14, as well as noble gases like xenon and krypton. These isotopes are monitored at multiple stations surrounding the 2-kilometer exclusion zone and the 5-kilometer warning zone.

Did you know: The adjacent Vysoký Hrádek castle, located just a few kilometers from the reactor buildings, houses a public information center that displays real-time radiation data from the plant’s monitoring network.

Post-Fukushima safety assessments have led to enhanced monitoring protocols. Following the 2011 disaster in Japan, the Czech Republic conducted a comprehensive stress test of its nuclear fleet. Temelín’s safety case was reviewed, leading to the implementation of additional mobile power sources and enhanced containment filtration systems. These upgrades were designed to mitigate the risk of a loss-of-coolant accident and to improve the removal of radioactive gases in the event of a prolonged station blackout.

Environmental Impact Assessment

The environmental impact of nuclear power generation is often measured in terms of land use and greenhouse gas emissions. Temelín contributes to the decarbonization of the Czech energy mix, displacing approximately 4.5 million tonnes of CO₂ annually compared to a typical hard-coal-fired plant of similar capacity. However, the lifecycle emissions include uranium mining, enrichment, and fuel fabrication, which add to the carbon footprint. The plant also generates low-level radioactive waste, primarily consisting of clothing, tools, and filters, which are stored on-site in concrete vaults pending final geological disposal.

Parameter	Value	Unit
Annual CO₂ Displacement	4.5	Million tonnes
Thermal Discharge	1,500	m³/s
Temperature Rise	5–6	°C
Annual Effective Dose (Public)	0.2–0.5	mSv
Exclusion Zone Radius	2	km

Controversy has occasionally arisen regarding the impact of the cooling water on the Lužnice River’s biodiversity. Environmental groups have pointed to the potential for thermal pollution to affect fish spawning grounds, particularly during summer months when water levels are lower. In response, the operator, ČEZ Group, has implemented a seasonal discharge schedule and has invested in habitat restoration projects along the riverbank. These measures aim to balance the need for efficient cooling with the preservation of the river’s ecological integrity.

The plant’s safety record has been largely positive, with no significant off-site radiation releases since its commissioning in 2000. However, the proximity to the Bohemian Forest and the Danube River basin has led to ongoing discussions about the potential for a transboundary impact in the event of a major accident. The Czech Republic has therefore maintained close cooperation with neighboring countries, particularly Germany and Austria, to coordinate emergency response plans and share real-time environmental data.

Economic Role and Workforce

The Temelín Nuclear Power Station represents a cornerstone of the Czech Republic’s baseload electricity generation. As the country’s largest single energy production facility, its two VVER-1000 reactors deliver a combined net capacity of approximately 2,000 MW. This output accounts for a significant share of the nation’s total installed nuclear capacity, which itself provides roughly half of the Czech electricity mix. The plant’s operational stability is critical for grid frequency regulation and load balancing, particularly as the country integrates more variable renewable sources like wind and solar.

Employment and Local Economy

ČEZ Group employs approximately 1,000 workers directly at the Temelín site. This figure includes engineers, technicians, administrative staff, and operational crews managing the reactor islands, turbine halls, and auxiliary systems. The workforce composition reflects the technical complexity of nuclear operations, with a mix of specialized roles in thermohydraulics, radiation protection, and mechanical maintenance. Indirect employment figures are often higher when including supply chain partners, contractors, and service providers that support the plant’s continuous operation.

The economic impact on the South Bohemian Region is substantial. The plant provides stable, long-term jobs in a region where agriculture and light industry have traditionally dominated. Local municipalities benefit from municipal taxes, property levies, and direct investments in infrastructure. The presence of the power station has also spurred the development of a local service sector, including housing, retail, and educational institutions tailored to the workforce’s needs.

Did you know: The adjacent Vysoký Hrádek Castle has been repurposed as an information center for the plant, offering guided tours that help bridge the gap between the local community and the nuclear facility.

The castle’s transformation into a visitor center is part of a broader strategy to enhance public acceptance and transparency. These tours provide insights into the plant’s safety systems, environmental monitoring, and daily operations. This engagement helps mitigate local concerns and fosters a more informed dialogue between the operator and the surrounding population.

Regional Development and Infrastructure

Temelín’s economic role extends beyond direct employment. The plant’s demand for raw materials, maintenance services, and logistical support stimulates local businesses. Construction and engineering firms, for instance, often secure contracts for upgrades, modernization projects, and periodic outages. The plant’s procurement strategy tends to favor regional suppliers, thereby retaining a portion of the economic value within the South Bohemian economy.

Infrastructure improvements have also been driven by the plant’s presence. Roads, power lines, and water supply networks have been upgraded to accommodate the facility’s needs. The Vltava River, which provides cooling water for the condensers, has seen enhanced monitoring and management to balance ecological health with thermal discharge requirements. These investments benefit both the plant and the broader region, creating a symbiotic relationship between industrial activity and local development.

The plant’s contribution to the national grid also has economic implications. By providing reliable baseload power, Temelín helps stabilize electricity prices and reduces the need for peaking power plants, which are often more expensive per megawatt-hour. This stability is particularly valuable during periods of high demand or when renewable generation is intermittent. The economic value of this reliability is reflected in the plant’s long-term contracts and its role in the Czech electricity market.

As of 2026, the plant continues to operate under the ČEZ Group, with ongoing investments in modernization and safety enhancements. These efforts aim to extend the operational life of the reactors and maintain their competitiveness in an evolving energy landscape. The economic and social benefits of Temelín are thus expected to persist, supporting both the local community and the national energy security framework.

Future Outlook and Expansion

Temelín’s operational horizon extends well beyond its initial design life, with ČEZ Group actively pursuing life extension and potential capacity additions to secure the Czech Republic’s baseload power. The plant currently relies on two VVER-1000/V320 pressurized water reactors, each contributing approximately 1,000 MW of net capacity. As of 2026, the first unit is scheduled to reach its initial 40-year design life, prompting rigorous technical assessments to justify extensions up to 50 or even 60 years. These extensions depend on the performance of key components such as the reactor pressure vessel, steam generators, and the primary circuit piping, which undergo continuous monitoring for neutron embritlement and thermal aging.

Life Extension and Technical Assessments

Extending the service life of nuclear units is a capital-intensive but strategically vital process for ČEZ. The operator has invested significantly in modernizing the plant’s safety systems, including the replacement of the control rod drive mechanisms and upgrades to the digital instrumentation and control (I&C) systems. These upgrades enhance operational reliability and reduce the frequency of short-term outages. Regulatory approval from the Czech Office for Nuclear Safety (ÚJZ) is required for each extension phase, involving detailed probabilistic risk assessments (PRA) and seismic reviews. The Temelín site benefits from a relatively favorable geological setting, though the 2003 commissioning of Unit 1 followed intense public scrutiny regarding seismic resilience, a factor that continues to influence maintenance priorities.

Did you know: The Temelín plant was originally designed with a modular approach, allowing for the potential addition of two more VVER-1000 reactors on the same site without requiring a completely new licensing framework for the general site conditions.

Potential for Expansion: Units 3 and 4

The possibility of constructing Units 3 and 4 at Temelín remains a recurring topic in Czech energy policy. While the site has the physical space and grid connection capacity for two additional 1,000 MW units, the economic and regulatory hurdles are significant. ČEZ has periodically evaluated the feasibility of adding these units, comparing the capital expenditure against the cost of new build projects at the Dukovany site or even new nuclear sites. As of 2026, no final investment decision (FID) has been made for Units 3 and 4, with the operator focusing on optimizing the performance of the existing two units and exploring small modular reactors (SMRs) as a more flexible alternative for future baseload needs. The decision will likely hinge on the stability of the Czech electricity market, the price of carbon allowances in the European Emissions Trading System (ETS), and the availability of skilled labor.

Role in the Czech Energy Strategy

Temelín plays a pivotal role in the Czech Republic’s energy mix, providing roughly 25% of the country’s electricity and serving as a key pillar for decarbonization through 2030 and beyond. The Czech government’s energy strategy emphasizes nuclear power as a stable, low-carbon source to complement the growing share of wind and solar generation. Temelín’s flexibility has been improved through upgrades to the turbine halls and heat recovery systems, allowing the plant to adjust its output more quickly in response to grid frequency changes. This flexibility is crucial for integrating variable renewable energy sources, reducing the need for costly gas-fired peaking plants. The plant also contributes to regional economic stability, employing around 1,000 workers and supporting local infrastructure through the adjacent Vysoký Hrádek castle information centre. Looking ahead, the continued operation of Temelín is essential for meeting the Czech Republic’s greenhouse gas reduction targets and ensuring energy security in a dynamic European market.

Temelin Nuclear Power Plant: Technical Profile and Operational History