Moscow and Kyiv accused each other of starting a fire on the grounds of the Russian-occupied Zaporizhzhia nuclear power plant on Sunday, as Ukraine urged residents to remain calm and reported no sign of elevated radiation. The UN’s International Atomic Energy Agency (IAEA) nuclear watchdog, which has a presence at the vast six-reactor facility, said its experts had seen strong, dark smoke coming from the northern area of the plant in southern Ukraine following multiple explosions. Ukrainian President Volodymyr Zelensky accused Russia of lighting a fire which he said was visible from the Kyiv-h…