Scientists working at Ukraine's Zaporizhzhia nuclear power plant say that it may need to be closed down due to nearby shelling and a general lack of safety amid "grave concerns" voiced by the UN nuclear watchdog. 

Ukraine accused Russia on Sunday of again shelling Europe's largest nuclear power plant at Zaporizhzhia, and called for new international sanctions on Moscow for "nuclear terror."

The country's state nuclear power firm said Russian forces damaged three radiation sensors at the facility in renewed shelling on Saturday night, wounding a worker with shrapnel.

The plant, in Russian-controlled territory, was also shelled on Friday. Moscow blames Ukrainian forces for the strikes.

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Vladimir Skalozubov, of the atomic energy department of Odesa Polytechnic University, told CGTN that there were "two ways out" of the current situation.

"Either shut down this nuclear power plant because of its tremendous instability," he said, "or continue with the current status quo keeping everything under Kyiv's control – including monitoring radiation levels."

But a decision to shut down the plant would be difficult, with Ukraine's four nuclear power facilities currently powering around half of the country's electricity.

Gravely concerned

The head of the UN's nuclear watchdog, the International Atomic Energy Agency (IAEA), expressed alarm over the shelling at the plant.

Rafael Mariano Grossi, IAEA director general, said: "I remain gravely concerned about the safety and security of nuclear facilities in Ukraine."

There is worry over failures to follow safety procedures, a lack of vital supplies and the obvious damage from shelling.

"For an emergency to cause events like the ones at Chernobyl or Fukushima, provoked action – like a powerful bomb hit – would have to happen. This is not inconceivable," said Skalozubov.

The European Union's top diplomat Josep Borrell condemned the shelling "as a serious and irresponsible breach of nuclear safety rules and another example of Russia's disregard for international norms."