The Danube's record low levels expose nuclear power plants in Hungary and Romania to climate risks

The record?low river levels in Hungary have forced the country to struggle to keep running its nuclear power plants, while Romania had to shut down?its last reactor. This has raised questions about how atomic energy can be adapted to an ever-more extreme climate. The reliance on river water to cool nuclear reactors is a long-standing issue and has led to a reduction in power production?in summer months. This has been especially true for France, whose nuclear power dependence is greater than any other country. The extreme heat and drought in Europe this year, where the continent has been experiencing more warming, have heightened the urgency of a discussion about adaptation.

Hungary's 2-gigawatt Paks Nuclear Plant was forced to reduce its output by just 10% in the beginning of this month. This is the first time since 1944 that a complete shutdown has been avoided. Now, it is operating at only 25% of its maximum capacity.

Nuclearelectrica, a Romanian state-owned company, shut down its final working reactor Thursday after it was not able to divert enough cooling water into the plant.

A PART OF THE SOLUTION, BUT ALSO PROBLEM The advantage of nuclear power plants is that they generate baseload electricity without carbon emissions. This means that they can play a part in preventing fossil fuel combustion and tackling climate changes.

Both Romania and Hungary have committed to increasing their nuclear power production to provide ample domestic energy. But to do so, they need to find a cooling system that is less dependent on the level of river water.

Diana Urge Vorsatz, a professor of Central European University, Vienna, stated that scientific modeling showed that Central Eastern Europe was on the rise.

She said that soil drying is due not only to the lack of rain, but also because groundwater levels and soil moisture have decreased over the years.

Water engineers warned at a conference of the Hungarian Hydrological Society last year that "flow patterns could become more extreme and volatil" on the Danube, Europe's longest river.

Governments are now under pressure to find solutions as emergency output reductions at Hungary and Romania's nuclei plants have forced them into asking companies and households to reduce?energy consumption. Peter Magyar, the Hungarian prime minister, said that his government was planning to build a "riverbed sill" - an underwater dam-like structure to raise water levels. Two barges may also be sunk to raise water levels on Friday in an effort to avoid a river shutdown.

The country is also reviewing designs for the planned Paks 2 expansion, which relies on the Danube as a cooling source. In 2014, the former Viktor Orban government selected Rosatom of Russia for the project without an open tender.

Different technology but still water required

Nuclearelectrica, a Romanian company, operates two reactors with a combined capacity of 706 megawatts. These reactors account for about a fifth (50%) of Romania's electricity production. The reactors use CANDU, a Canadian technology which relies on heavy-water, where the hydrogen in the water is replaced with a heavier element to slow down neutrons.

Russian pressurised-water reactors are used in the four reactors at Hungary's Paks Plant, which produce around half of Hungary’s electricity.

Both technologies use water from the Danube to cool the air and then return the water into the river.

In contrast, Czechoslovak nuclear plants use wet-cooling towers that require?less water. The steam emitted in the process is then emitted into the atmosphere.

Scientists have proposed a hybrid cooling system that combines river cooling and tower cooling.

Attila Azzodi is a professor and nuclear expert from the Budapest University of Technology and Economics. He said that retrofitting a cooling system to the original Paks Reactors would not be cost-effective.

Aszodi said: "I do not think it is cost-effective to install a large cooling system for the next twenty years, i.e., the remaining life of the Paks 1 plant." "A new assessment of the cooling methods on site is absolutely necessary."

ROMANIA PLANS AN INTERVENTION ON THE DANUBE

The only nuclear power plant in Romania is located on the Old Danube branch of the river, which intersects Bala.

The government has approved a project in 2024 worth 1,02 billion lei (225 million dollars) to raise the riverbed of the Bala Branch to regulate the water flow.

The solution proposed?includes moving upstream the intersection of branches, and raising the riverbed sill along the deeper Bala arm.

The government has not provided any information about when the project could be completed. Nuclearelectrica responded that studies had shown the Bala project to be a way of ensuring four reactors can operate at their full capacity, when asked about the effect low Danube levels would have on plans to build two additional reactors. Eugenia Gushilov, director at the Romania Energy Center, said it is feasible and that alternative cooling methods can be considered before work begins.

She said that "Building Units 3, 4 and 5 still makes sense, if necessary hydrotechnical work is done."

(source: Reuters)