Unit 1 at Cernavodă Nuclear Power Plant prepares for grid synchronization
Nuclearelectrica announced Wednesday that Unit 1 of the Cernavodă Nuclear Power Plant will be synchronized with the national energy system on Friday, November 6, 2026. The reactor, which has been offline since July 28, 2026, began specific startup maneuvers on November 4.
This milestone marks the end of a 100-day period during which the unit provided no electricity to the national grid. The reactor is expected to reach its nominal power capacity by the evening of November 7.
Nuclearelectrica details strict nuclear safety requirements for startup
The startup process for a nuclear unit is a strictly regulated and complex operation. Nuclearelectrica emphasized that the procedure follows rigorous nuclear safety requirements to ensure a secure return to the national energy system (SEN).
Mihai Gioară, Director General of Nuclearelectrica, described the reconnection as an important step for the company, public, and national authorities. He noted that specialists at the plant maintained the units in safe conditions throughout the entire duration of the shutdown. The company is currently working with authorities and partners to develop solutions to improve installation availability should similar events occur in the future. Începerea manevrelor de pornire a Unității 1, odată cu îndeplinirea condițiilor minime pentru pornirea în deplină siguranță, este un pas important, așteptat deopotrivă de companie, de autorități și de public
, stated Mihai Gioară in a statement to the Bucharest Stock Exchange.
Water levels and the status of Unit 2
While Unit 1 prepares for service, the status of Unit 2 remains tied to the hydrological conditions of the Danube. Operation of Unit 1 requires significant volumes of water for reactor cooling, which causes the level in the suction basin to drop.
Nuclearelectrica stated that the restart of Unit 2 depends on a sustained increase in the river’s level. Prin urmare, pornirea Unității 2 depinde de o creștere susținută a nivelului Dunării
, according to the company. The Danube’s flow at the Baziaș entry point was measured at 1,700 m³/s on Wednesday morning, which remains below the multi-annual average for November of 4,700 m³/s. Both units were originally taken offline in the summer due to low water levels, with Unit 1 ceasing operations on July 28, 2026, and Unit 2 being disconnected on August 13, 2026, which resulted in a total shutdown of the facility.
Broader energy system constraints
The return of nuclear capacity comes as the government maintains measures to manage energy security. Prime Minister Luca Niculescu noted that the restart could be a matter of days due to improved Danube flows from recent rainfall, stating, Sper să avem vești bune în câteva zile
. The government extended until November 30 the authority for Transelectrica to limit electricity consumption for large industrial users and restrict energy exports if necessary. The Prime Minister stated that Romania's gas reserves are currently near the 90% threshold set by the EU and noted that the National Energy Committee will be convened soon to secure supply.
Forecasts for November indicate that peak evening electricity demand could reach 8,500 MW, a figure that may rise if temperatures drop significantly below seasonal averages.
Common questions regarding the Cernavodă restart
Why was the Cernavodă nuclear plant completely shut down?
Both units were taken out of service because the flow of the Danube dropped below the level required for the safe cooling of the reactors. Unit 1 was shut down on July 28, 2026, followed by Unit 2 on August 13, 2026.
When will the second reactor be back online?
Nuclearelectrica has not provided a specific date for Unit 2. The restart is contingent upon a sustained increase in the water level of the Danube, as the cooling process for Unit 1 will consume large volumes of water once it is operational.
What is the impact on the national energy system?
The plant usually provides approximately 20% of Romania’s electricity production. To manage the shortfall, the government has authorized the national grid operator to restrict exports and limit consumption by large industrial users through the end of November. Meanwhile, the Ministry of Finance addressed recent Eurostat deficit data, attributing it to accelerated large-scale investments during the first half of the year.
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