Romania Sunk 4 Ships Trying To Stop A Nuclear Reactor Failure

Romania sunk four barges in the Danube River in August 2026 as part of an effort to keep sufficient water levels flowing to its Cernavoda nuclear plant, which uses the river’s water for cooling purposes. The plan to sink these four barges came in response to declining water levels in the Danube that have been affected by severe droughts across Europe this summer. The river’s flow had fallen to a record low of 49,440 cubic feet per second for this time of year. 

The four barges were filled with rocks before being sunk in the river as part of efforts to divert water flow to the country’s only nuclear plant. A large rock was also blasted away to aid the redirection efforts. The sinking of these four ships was an unprecedented event that ultimately failed to stop the plant from shutting down. Romania’s nuclear energy company, Nuclearelectrica, announced on August 13 that it would commence a controlled shutdown of the plant’s second and last reactor as a result of the shortfall in available cooling water. 

The first had already been shut off in July. The Cernavoda nuclear power plant uses water as its primary heat sink mechanism, and the shutdown illustrates how critical ample water supply is to a nuclear power plant’s operation. Without a steady supply of river water, this plant cannot function safely.

Nuclear power plants work by generating heat from nuclear fission and converting surrounding water to steam, which drives turbines connected to electric generators. Water is critical for this steam conversion. The process of driving mechanical power is more efficient the larger the difference in temperature between the internal heat source and the external environment where the heat is released. This is why water-cooled nuclear plants are built close to cold water sources. 

Water is recycled after steam is used to drive turbines, which is achieved by cooling and condensing low-pressure steam. Cernavoda’s nuclear cores are cooled and moderated by heavy water (deuterium oxide). While the river isn’t used as a primary cooling mechanism, it is used as the external heat sink. Water-cooled nuclear plants don’t just need water for cooling when the reactor is active, but also after the reactor is shut down.

Heat will continue to be generated by nuclear decay even after a plant has been shut down, which is why all water-cooled nuclear plants have emergency water supplies. It is a backup in the event the primary water source is compromised, though the Cernavoda nuclear plant was shut down before having to tap this supply. Water cooling systems are key to stopping nuclear meltdowns, which have previously occurred due to cooling system breakages.

The Cernavoda nuclear power plant’s shutdown is an example of why it may sometimes be better to consider alternative cooling methods, especially if the plant’s water supply is vulnerable to climate change. Ironically, nuclear power plants could be used to provide desalinated seawater, which is one of three unexpected uses for nuclear energy. Dry cooling techniques are viable options in cases where water sources are scarce, and rely on air as the heat transfer mechanism.

One type of air cooling works similarly to a car radiator, where fan-driven airflow passes through a system of finned tubes in the steam condenser. The heat is transferred to the ambient air in this case. Solutions like these require less than 10% of the amount of water used by water-cooled plants, but lose up to 1.5% of power output to driving the fans.

Another type of air cooling works similarly to the fan-driven example, but in this case water is enclosed and cooled by airflow past finned tubes in a cooling tower. Heat is still transferred to the air, but this method is not as efficient. Lead-cooled nuclear reactors are also starting to emerge, and could be the future of nuclear power. In this case, molten lead is used to passively cool nuclear cores via convection.