Ukraine’s military on Saturday reported fresh shelling at the Zaporizhzhia nuclear power plant complex in southern Ukraine, hours after the European Union late Friday joined the United States in calling for the immediate creation of a demilitarized zone around the plant. International concern has grown as the bombing of the plant raises the risk of igniting a fire or causing other damage that could get out of control and lead to a nuclear accident. Ukraine has accused Russia of directing strikes there to cut off power to other cities and try to discredit the Ukrainian military in the eyes of the world. The Russians say Ukraine is doing the bombing. In his late-night speech on Saturday, Ukrainian President Volodymyr Zelensky said the situation at the nuclear power plant was a threat to the rest of Europe as well. Every day that Russian forces occupy the plant and the area around it “increases the radiological threat to Europe so much that, even at the height of the confrontation during the Cold War, this did not happen.” On Saturday, Ukraine’s military intelligence service accused Russia of using the occupied town of Vodyane, which is near the plant, as a staging post to bomb the facility. They also accused Russia of planning a false-flag propaganda event to make it appear that Ukrainians are responsible for hostilities around the complex. The intelligence agency said that, among other things, Russian forces brought Ukrainian flags to positions where their artillery was located. The claims could not be independently verified, but reflect the Ukrainian belief that Russia is using the plant as a form of nuclear blackmail aimed at scaring Ukrainians and their international allies about the consequences of any attempt to reclaim land now held by Russia . At the same time, Russian state media Ria Novosti reported that Ukraine launched an artillery attack on the plant, firing at least nine shells that landed near the complex. The publication cited a local official of the Russian occupation administration. It could not be independently confirmed. It was not immediately clear what damage was caused by the new shelling on Saturday. Both sides will suffer if the plant, Europe’s largest, collapses and releases radioactive material. While such plants are designed to withstand a range of hazards—from a plane crashing into the facility to natural disasters—no nuclear plant in operation has ever been in the midst of active combat, and this one was not designed with the threat of cruise missiles in mind. The concrete shell of the site’s six reactors offers strong protection, as it did when the No. 1 reactor was hit in March, officials say. More worrying is the possibility of a power transformer being hit by a bomb, increasing the risk of fire. If the power transformers caught fire and the power grid went offline, it could damage the plant’s cooling system and lead to a catastrophic meltdown, said Edwin Lyman, a nuclear energy expert at the Union of Concerned Scientists. , a private group in Cambridge, Mass. He noted that the loss of coolant in Japan’s 2011 Fukushima accident resulted in three reactors suffering some degree of core meltdown. If the cooling is stopped, Dr. Lyman said, the nuclear fuel could become hot enough to melt within hours. Eventually, it could melt through the steel reactor vessel and even the outer containment structure, releasing radioactive material.