Romania mulls Cernavodă reactor shutdown

SN Nuclearelectrica has warned that there is a possibility of a controlled shutdown of Unit 2 of the CNE Cernavodă nuclear power plant in the morning of 13 August 2026. The warning follows a period of falling water levels on the Danube, which supplies cooling water to the plant. The national water authority has stated that the river level at Cernavodă has reached the minimum operating threshold of -230 cm, a point at which safety procedures must be prepared.

Pre-shutdown safety procedures for the unit can take up to 48 hours, indicating that operators must plan and sequence actions before any shutdown is carried out. Authorities are monitoring conditions closely as the river remains at or near critical values for continued safe operation of the reactor.

In response to record-low flows on the Danube, Romanian authorities have implemented emergency riverworks around the Cernavodă site. These measures included controlled explosions on a submerged rock formation, dredging of the river bed, and the controlled sinking of rock-filled barges to influence local water levels. Officials said that these interventions raised the water level around the plant by about 4 cm.

According to ministers and plant officials, the additional 4 cm of water level could allow the remaining reactor to continue operating for roughly nine more days. However, hydrological forecasts cited by authorities indicate that the Danube’s level is expected to continue declining in the near term, which would gradually reduce the extra operating margin provided by the emergency works.

The single operating unit at Cernavodă supplies about 680 MW of electricity, which is cited as roughly one-tenth of Romania’s peak national demand. Romania’s two nuclear reactors together are described as providing about 20% of the country’s electricity output. A shutdown of Unit 2 would therefore remove a significant source of baseload generation from the national grid.

To address potential supply shortfalls, the government has prepared an emergency mechanism allowing transmission system operator Transelectrica to disconnect certain large industrial consumers with 24 hours’ notice if available generation cannot cover projected demand. Under this mechanism, households, hospitals and critical infrastructure would be exempt from curtailment, ensuring continuity for essential services even if the reactor is taken offline.

Hydrological forecasts referenced by officials suggest continued declines in Danube water levels, which could bring the river below technical thresholds for safe operation in the area of the plant. If these projections materialise, the short-term operating window created by the emergency riverworks will narrow further.

Authorities are balancing the need to maintain electricity supply with strict safety requirements for nuclear operation. Decisions on whether and when to proceed with a controlled shutdown of Unit 2 will depend on the evolution of river levels, the effectiveness of previously implemented measures, and real-time assessments by plant operators and relevant agencies.