In 2025 nuclear energy remains the single most reliable anchor of baseload stability in South-East Europe. While solar and wind are rapidly reshaping the regional power profile, nuclear is what quietly keeps frequency stable, dampens volatility, underpins export surpluses in key systems and protects national balances from fuel price shocks. It is not expanding everywhere, but where it exists, it has become financially decisive and strategically irreplaceable within the current decade.
Bulgaria is the region’s core nuclear player. The Kozloduy nuclear power plant, operating with two 1,000 MW VVER units, provides about 2,000 MW of dependable baseload. In 2025 Kozloduy typically produces between 14 and 16 TWh annually depending on maintenance schedules and operating regimes. This means that nuclear alone accounts for more than one-third of Bulgaria’s total power generation. Economically, this matters because nuclear delivers predictable, low-marginal-cost electricity insulated from gas and coal price spikes. It is one of the core reasons Bulgaria consistently ranks as one of the largest net electricity exporters in Europe. Annual net exports in recent years have sat around 10 to 12 TWh, and nuclear is structurally responsible for the stable export floor, while coal and renewables shape the incremental export volume. The presence of nuclear makes Bulgaria’s trade balance stronger, stabilises wholesale prices, and gives investors confidence that Bulgaria’s system is anchored by non-volatile supply.
Romania is the second major nuclear pillar in the region. The Cernavodă plant operates two CANDU 6 units with a combined installed capacity of roughly 1,400 MW. In a normal operating year these units generate 10 to 11 TWh of electricity, regularly providing 18 to 20 percent of Romania’s total electricity consumption. Importantly, unlike renewables that fluctuate daily and hydro that fluctuates seasonally, Cernavodă runs with exceptionally high capacity factors, often above 85 to 90 percent, meaning it behaves almost like industrial infrastructure rather than a power plant in energy market terms. It stabilises Romania’s supply curve, reduces reliance on coal and gas, and strengthens the country’s ability to export electricity during high-generation conditions. Romania’s broader nuclear programme also includes the decision to complete Units 3 and 4 during the next decade, which if realised would push nuclear beyond 30 percent of national supply and transform Romania into a long-term regional stability exporter in electricity as well as a hub for nuclear engineering capability.
Hungary, while not always grouped into the Balkans politically, is highly relevant to the South-East European power environment and directly connected to regional flows. The Paks nuclear plant operates four units with a combined capacity of roughly 2,000 MW, producing 15 to 16 TWh annually. This covers around half of Hungary’s electricity needs and, critically, reduces Hungary’s dependence on gas-fired generation. Even though Hungary is not a permanent net exporter like Bulgaria, nuclear dramatically softens Hungary’s import exposure and helps stabilise cross-border prices and supply flows that Romania, Serbia and Croatia depend on. The Paks II expansion project, aimed at adding two new nuclear units in the early 2030s, signals that Central and South-East Europe are not moving away from nuclear; they are doubling down on it as an energy sovereignty instrument.
Slovenia plays a quieter but strategically notable role in regional nuclear stability through the Krško nuclear power plant, jointly owned with Croatia. Krško has a capacity of around 700 MW and typically generates between 5 and 6 TWh per year. This production is effectively split between Slovenia and Croatia, meaning Croatia receives roughly 2.5 to 3 TWh of stable, low-carbon baseload electricity each year. For a country with total annual consumption of roughly 16 to 18 TWh, this is a large and strategically important share. It directly reduces Croatia’s import needs, supports price stability, and balances the variability introduced by wind and solar. Slovenia, for its part, benefits from nuclear as a strategic hedge, reducing fossil generation needs and securing long-term baseload independent of hydrology or commodity cycles. Current policy discussions in Slovenia on extending Krško’s operational life to 2043 or potentially building a second unit underline the economic logic: nuclear lowers long-term system risk and strengthens national competitiveness.
These nuclear anchors contrast sharply with countries that do not have nuclear power. Serbia, Bosnia and Herzegovina, Montenegro, Albania and North Macedonia all operate with power systems that rely on some combination of lignite, gas, hydro and rising renewables. None of them possesses civilian nuclear generation capacity in 2025. The absence of nuclear means that baseload stability must come either from coal, which carries rising carbon, environmental and financial liabilities, or from imports, which introduces price risk, forex risk and structural exposure to neighbouring market behaviour. Serbia has compensated historically through lignite and hydro, but after the energy crises of recent years, the strategic value of a non-fossil baseload anchor like nuclear is becoming clearer to policymakers. Bosnia and Herzegovina is shielded by hydro diversity and coal but still exposed in dry or stress scenarios. Albania remains vulnerable because hydropower volatility translates almost directly into import dependency when rainfall fails. In every one of these systems, nuclear absence equates to structural exposure to external markets and a reliance on fossil flexibility or price-driven imports.
If we combine existing nuclear output across the wider South-East European power space in 2025, the numbers are macro-significant. Bulgaria contributes around 15 TWh per year, Romania around 10 to 11 TWh, Hungary around 15 to 16 TWh, and Slovenia roughly 5 to 6 TWh, meaning the regional nuclear base collectively produces well above 40 TWh annually. This is equivalent to the entire annual electricity consumption of a country the size of Serbia. Moreover, this nuclear production is not intermittent; it is firm, schedulable, baseload energy that keeps networks balanced and gives traders confidence in forward positions.
Financially, nuclear’s value in the regional electricity system is stark. First, it dampens wholesale price volatility. When nuclear contributes solid baseload volumes into the market, short-run marginal pricing is less dominated by gas and coal units, reducing exposure to fuel spikes. Second, it strengthens export saldos by ensuring nations like Bulgaria and Romania can maintain reliable export volumes even when renewable output fluctuates. Third, it materially improves national carbon exposure. Each TWh of nuclear replaces a TWh of fossil-based electricity that would otherwise attract carbon costs domestically or indirectly under mechanisms such as CBAM. In practical macro terms, nuclear in SEE in 2025 is simultaneously a price stabiliser, a trade tool and a carbon hedge.
Operationally, nuclear also acts as the backbone that allows renewables to grow. Solar and wind require balancing resources to manage variability. Nuclear cannot ramp like gas or hydro, but it provides the firm base that allows flexible assets to focus on balancing rather than carrying the entire system load. In Bulgaria, nuclear plus coal gives breathing room to absorb rising solar without risking supply security. In Romania, nuclear plus hydro provides structural flexibility while gas and imports handle residual balancing needs. In Croatia and Slovenia, Krško’s stable output makes it easier to integrate wind and solar without creating reliability anxiety.
In investment terms, nuclear in SEE is entering a period of strategic consolidation and selective expansion rather than decline. Bulgaria is actively pursuing new nuclear development, including the planned Belene and Kozloduy expansion options, because policymakers understand that regional competitiveness in the 2030s will depend on who controls affordable, large-scale, non-fossil baseload. Romania is advancing its two-unit expansion plan and additional small modular reactor initiatives, positioning itself not just as a nuclear user but as a regional nuclear technology hub. Hungary is moving forward with Paks II to secure long-term price and supply sovereignty. Slovenia is debating its nuclear future as part of an explicit energy security and cost competitiveness strategy. These are not projects driven by ideology; they are driven by arithmetic, system stability logic and geopolitical risk management.
For countries without nuclear, the policy debate is shifting from “if” to “how do we balance without it?” In systems without nuclear, there must be a heavier reliance on a mix of gas capacity, large hydropower investments, storage, imports and tighter market integration. This means higher CAPEX in flexibility infrastructure and higher OPEX exposure to imported energy. It is a viable strategy, but it requires efficiency, precision and sustained investment discipline.
The reality in 2025 is simple. Nuclear is the strategic stabiliser of South-East Europe’s power system. It supports export strength, keeps wholesale prices grounded, reduces carbon exposure, strengthens investor confidence and underpins the ability to integrate rapidly expanding renewables. As renewables continue to grow through 2030, nuclear’s importance will not decline; it will rise, because systems with strong intermittent renewable fleets require firm, predictable anchors. In South-East Europe today, that anchor is nuclear power, and its role in the regional electricity economy is both structurally and financially decisive.
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