Record-low Danube water levels threaten cooling at Romanian and Hungarian nuclear plants

Romania and Hungary spent the first week of August trying to keep Danube-fed nuclear reactors running as record-low river levels cut into cooling-water access during a heatwave across central and southeastern Europe. Romania used explosives and then prepared to sink loaded barges to redirect more water toward the Cernavoda plant, while engineers at Hungary’s Paks station monitored the river level minute by minute. Insurance Journal, citing reporting by Bloomberg journalists Andra Timu, Thomas Escritt, Daniel Hornak and Andrea Dudik, said on August 5 that the shrinking river was threatening electricity supplies in both countries. AP reported on August 4 that governments across the region were already moving to conserve power as the Danube’s low flow threatened generation. ### Which plants are under pressure from the Danube? Hungary’s Paks nuclear power plant and Romania’s Cernavoda nuclear power plant both rely on Danube water for cooling. Insurance Journal said Paks, when running at full capacity, contributes 40% of Hungary’s electricity supply. Reuters reported on August 3 that Cernavoda was Romania’s sole operational nuclear site and that the emergency river works were meant to protect its last working reactor. (insurancejournal.com) Romania’s operator had already cut output before the latest river works. World Nuclear News reported on July 30 that one of Cernavoda’s two units had been shut down, while MVM Paks said the same day that a full shutdown of Hungary’s plant could become unavoidable within 24 to 72 hours because of the Danube’s low level. ### Why does low river water threaten a nuclear plant if the reactors are intact? (insurancejournal.com) The immediate issue is cooling water, not reactor fuel. MVM Paks said Danube water is needed for cooling the condensers, and Reuters reported that the running turbine at Paks was being cooled by water drawn from the river. When the river falls too far, operators can be forced to reduce output or halt units to protect equipment and maintain safe operating conditions. (world-nuclear-news.org) AP reported that low water levels on the Danube were threatening power plants across Central and Eastern Europe, while DW said Cernavoda draws all of its cooling water from the river. Reuters described Romania’s action as an effort to increase the flow of “vital cooling water” to Cernavoda. ### How close did Hungary come to a shutdown? At Paks, the margin was extremely narrow. (atomeromu.mvm.hu) Insurance Journal reported that the chief engineer on the overnight shift was within a millimeter of ordering the shutdown of the last remaining turbine before the Danube rose by 5 centimeters, according to Prime Minister Peter Magyar. Tamas Cseh, a member of parliament for the town of Paks, told Bloomberg that the rise was “a huge stroke of luck.” (apnews.com) The plant had already lost most of its output. AP reported that Paks had been pushed to the brink of powering down entirely, and CBS said on August 6 that three of its four units were not operating while the fourth was running at about 50% as of Wednesday morning. ### What exactly did Romania do on the river? Romania carried out emergency engineering works upstream of Cernavoda to raise the water level by centimeters. (insurancejournal.com) Insurance Journal said the week began with a blast using nearly 400 pounds of explosives to break a rock formation in the river, and that the next step was to sink loaded barges on Wednesday to try to raise the Danube further and push water downstream toward the plant. Reuters reported the blast on August 3 and said the action was intended to redirect cooling water to the last working reactor. (apnews.com) Romanian water officials also put a rough time limit on how long operations could continue under the existing conditions. Agerpres, citing Sorin Rindasu, deputy director-general of the Romanian Waters National Water Administration, reported on August 1 that the Danube near Cernavoda was falling by about 2 to 3 centimeters a day and that the plant could operate for another four to five days at the limit under those conditions. (insurancejournal.com) ### Is this only a nuclear story? The Danube problem is broader than the two plants. Insurance Journal said the river’s record low was disrupting cargo traffic and tourist cruises from Bratislava to Belgrade, and AP reported that governments in the region were taking steps to conserve electricity and avert an energy crisis. CNBC said on August 5 that low Rhine and Danube levels were disrupting energy generation, freight and river transport across Europe. (agerpres.ro) Wednesday’s barge operation near Cernavoda was the next concrete step identified by Romanian authorities and by Bloomberg’s August 5 account. Hungary’s plant operators, meanwhile, were still watching the Danube level in real time, with Paks remaining dependent on any further rise in the river. (insurancejournal.com)