Tokyo Electric Power Co (Tepco) has blamed an explosion at Fukushima this week on a heavy machinery robot working on the stricken nuclear plant.
Kyodo News reported that an explosion at 2.30pm on Tuesday was heard at the Fukushima Daiichi nuclear complex.
Tepco said a remote controlled robot deployed on the southern side of the No. 4 reactor building to remove wreckage could have ruptured a gas tank under the plant.
Tepco confirmed that radiation levels had not increased and there had been no injuries from the incident.
