Hydro and gas reserves replace Cernavoda Unit 2 — NRG-IA

The Ministry of Energy's emergency plan — how the 700 MW deficit will be covered The Ministry of Energy is activating hydro reserves to replace the 700 MW from Cernavoda. The National Power System (SEN) has the necessary capacities to cover this major production deficit, according to an official briefing issued by the institution. Authorities are relying on close coordination between the national dispatcher and major producers to maintain grid equilibrium. According to data published by Economica.net and e-nergia, the controlled shutdown of the nuclear reactor is scheduled to begin tomorrow. The Ministry of Energy emphasizes that security of supply is at no point compromised. However, the replacement mix will heavily depend on hydrological conditions in the national river basins and real-time consumption trends. This planned shutdown tests grid flexibility during a seasonal transition period. Unit 2 of the Cernavoda plant typically covers nearly 10% of Romania's national electricity consumption. In the absence of this constant baseload production, energy dispatchers must resort to fast-start sources. Hydropower plants and gas-fired power plants will represent the first line of balancing. These will be supplemented by cross-border imports if prices in regionally coupled markets are advantageous. Preventive maintenance works — the cause of the nuclear reactor shutdown The decision to perform a controlled shutdown of Unit 2 is a standard technical measure required for preventive maintenance and unforeseen repairs that cannot be postponed. The state-owned company Nuclearelectrica applies strict industrial safety protocols, and these shutdowns are periodically scheduled to ensure optimal long-term operations. Although the schedule is set in advance, the timing puts pressure on other domestic producers. Unlike unplanned outages, a controlled shutdown allows Transelectrica and its balancing market partners to adjust their bids and reserve volumes in advance. However, temporarily taking a nuclear unit offline represents a significant logistical challenge. The process requires replacing cheap, constant energy with sources that have much higher marginal production costs, such as hydrocarbons. Pressure on spot prices and the utilization of interconnectors Substituting nuclear energy with hydro or gas-fired power will directly influence the spot price of electricity on the OPCOM platform. Nuclear energy is one of the cheapest resources in the Romanian mix, and replacing it with more expensive dispatchable units tends to drive up the average market clearing price. For household consumers, the direct impact on bills is limited in the short term by capping schemes, but financial pressure shifts to the state budget and suppliers. On the wholesale market, part of the 700 MW deficit will be covered by cross-border commercial flows through interconnectors with Hungary, Bulgaria, and Ukraine. If neighboring grids also face high temperatures or local deficits, import prices may experience temporary increases. In this context, hydropower plants managed by Hidroelectrica become the critical pillar of stability, but their intensive use depends directly on water reserves accumulated in large reservoirs. Hydrological monitoring and the uncertain restart timeline The Ministry of Energy is closely monitoring Danube water flows and reservoir filling levels to calibrate the use of hydro resources in the coming weeks. Low hydrology could limit Hidroelectrica's generation capacity, forcing a heavier reliance on coal-fired plants from Complexul Energetic Oltenia or imports. The final dispatching decision will be made daily based on weather forecasts and consumption fluctuations. The restart of Unit 2 is expected to take place after all safety tests are completed, but authorities have not yet provided a firm calendar date for grid reconnection. Until then, the consumption behavior of large industrial consumers and the availability of wind and solar farms will determine whether Romania remains a significant net importer during this period. Careful monitoring of cross-border flows remains essential to avoid transport grid congestion.