The Fukushima 1 plant has been hit by two explosions at buildings housing two reactors since a massive 8.9-magnitude earthquake hit on Friday, and the cooling system at another reactor stopped working Monday.
But chief government spokesman Yukio Edano said that ongoing work to cool that reactor would hopefully stabilise the situation.
He said radiation around the plant 250 kilometres (155 miles) north of Tokyo was at a tolerable level for humans.
TEPCO said that 3.7 metres (12.14 feet) of the reactor’s four-metre fuel rods were exposed to the air as of 8.07 pm (1107 GMT), before the pumping of seawater resumed.
It said the pump had stopped for just over two hours when its fuel ran out.
Earlier in the day, a blast rocked a building housing the number-three reactor and injured 11 people.
A similar explosion had hit the building housing the number-one reactor on Saturday, a day after a huge quake generated a wall of water that swamped a swathe of the country’s Pacific coast.
Edano said Monday’s explosion did not breach the reactor container. “The figures do not indicate a high level of radiation,” he added.