If hydropower defined when prices moved in January, nuclear power defined how far they could move on average. Nuclear generation acted as the region’s most important structural price anchor, providing constant baseload that dampened fuel-driven volatility and enabled sustained exports even during winter stress. Its role was not visible through dramatic price spikes, but through what did not happen: prolonged scarcity driven by fuel shortages or baseload inadequacy.
South-East Europe’s nuclear footprint is concentrated but systemically powerful. Bulgaria’s Kozloduy Nuclear Power Plant and Romania’s nuclear fleet together provide roughly 4 GW of stable baseload capacity, operating with high availability and predictable output. During January, these units ran close to full load, anchoring national balances and allowing surrounding systems to arbitrage against a relatively low and stable marginal cost.
Bulgaria’s nuclear output was a key reason the country remained a net exporter during large parts of January. Despite elevated regional power prices, Bulgaria was able to supply significant volumes northbound, particularly into Romania, where more than 400 GWh flowed from Bulgaria to Romania through the month. This export capability materially shaped OPCOM price formation. Without nuclear-backed exports, Romanian peak prices would likely have cleared even higher, especially during evening ramps when domestic flexibility tightened.
Nuclear’s influence differs fundamentally from hydro’s. Where hydro responds dynamically to price signals, nuclear suppresses the baseline upon which those signals act. Bulgaria’s nuclear generation ensured that a large portion of the regional demand curve was met at a cost well below marginal gas or scarcity pricing, even as TTF gas traded in the €28–34/MWh range. This meant that gas-to-power units were often not the marginal price setter, particularly during off-peak and shoulder hours.
Romania illustrates the same effect from a different angle. Despite having domestic gas production and hydro resources, Romania’s nuclear output was essential in maintaining system adequacy during January. Yet OPCOM still cleared at the region’s highest averages. This apparent contradiction highlights nuclear’s true role: it stabilises volumes and reduces volatility, but it does not eliminate price premia caused by congestion, flexibility shortages, or regional import dependence. Nuclear flattens the lower half of the supply curve; it does not address the upper tail created by ramping constraints.
In Croatia and Slovenia, the Krško nuclear plant plays a similar anchoring role, albeit indirectly through shared ownership and imports. While Croatia lacks domestic nuclear generation beyond its share of Krško, the plant’s steady output reduces the region’s reliance on gas-fired baseload and moderates average prices during non-peak hours. This helps explain why Croatia’s baseload averages, while high, did not drift further upward despite frequent peak stress.
Crucially, nuclear also shaped market confidence. Unlike gas or hydro, nuclear availability is largely immune to short-term weather risk. In January, this reliability reduced the risk premium embedded in forward and spot prices. Market participants could assume that a substantial portion of regional demand would be met regardless of wind lulls, cold snaps, or import congestion. That assumption limits the escalation of sustained scarcity pricing, even when individual hours clear at extreme levels.
From a trading and system-planning perspective, nuclear’s January contribution was therefore structural rather than opportunistic. It reduced the frequency of system-wide emergencies, enabled consistent cross-border exports, and kept gas from becoming the dominant price driver. The fact that SEE power prices spiked without a corresponding gas price shock is itself evidence of nuclear’s stabilising role: fuel scarcity was not the trigger; flexibility scarcity was.
For systems without nuclear access, January reinforced a structural disadvantage. Montenegro and, to a lesser extent, Serbia and Croatia faced higher exposure to volatility because they relied on imports from nuclear-backed systems rather than owning the anchor themselves. This asymmetry will only grow as electrification increases demand for stable baseload.
January demonstrates that nuclear power in South-East Europe is not merely a legacy asset. It is the foundation upon which market stability rests. While hydro determines the shape of prices and gas influences marginal economics at the edges, nuclear defines the floor. As long as nuclear availability remains high, SEE markets will experience sharp spikes but avoid prolonged crises. Remove that anchor, and the same January conditions would have produced not just volatility, but systemic stress.
