TEHRAN, Iran—Iran’s sole nuclear power plant has undergone an unexplained temporary emergency shutdown, state TV reported on Sunday. An official from state electric company Tavanir, Gholamali Rakhshanimehr, said on a talk show that the Bushehr plant shutdown began on Saturday and would last “for three to four days.” Without elaborating, he said that power outages could result. This is the first time Iran has reported an emergency shutdown of the plant, located in the southern port city of Bushehr. It went online in 2011 with help from Russia. Iran is required to send spent fuel rods from the reactor back to Russia as a nuclear nonproliferation measure. Earlier on Sunday, Tavanir released a statement saying that the nuclear plant was being repaired, without offering further details. It said the repair work would take until Friday. In March, nuclear official Mahmoud Jafari said the plant could stop working since Iran cannot …