ZURICH (Reuters) -The head of the International Atomic Energy Agency (IAEA) raised grave concerns on Saturday about the shelling the previous day at the Zaporizhzhia nuclear power plant in Ukraine, saying the action showed the risk of a nuclear disaster. Both sides accused each other on Saturday of engaging in “nuclear terrorism”. Ukraine’s state nuclear power company Energoatom blamed Russia for the damage while Russia’s defence ministry accused Ukrainian forces of shelling the plant. “I’m extremely concerned by the shelling yesterday at Europe’s largest nuclear power plant, which underlines …