The exterior of reactor No. 3 at Fukushima Daiichi nuclear plant is seen in this still image taken from undated file video footage. Japan battled to contain a radiation leak at an earthquake-crippled nuclear plant on March 13, 2011, but faced a fresh threat with the failure of the cooling system in a second reactor. – Reuters Photo

TOKYO: There is a risk of an explosion at a building housing a nuclear reactor damaged by a massive earthquake in northeastern Japan after a buildup of hydrogen, although it is unlikely to affect the reactor’s core container, Japan’s Chief Cabinet Secretary Yukio Edano said on Sunday.

An explosion on Saturday blew off the roof of another reactor building at the Fukushima Daiichi nuclear plant.

A Trade Ministry official said there could be power shortages in areas covered by Tokyo Electric Power Co and Tohoku Electric Power Co, power outage were expected in some areas to avoid complete blackouts.

The official said TEPCO would select five areas of 5 million kilowatts each, and the areas would have planned blackouts of three hours in turn when power supplies were short.

Top of fuel rods above water

The operator of quake-hit Japanese nuclear reactors said Sunday the top of fuel rods had been three metres (10 feet) above water, an indication of a possible meltdown.

Tokyo Electric Power (TEPCO) warned that the number three reactor at Fukushima No. 1 plant was overheating and that so much of the cooling water had briefly evaporated that mixed oxide fuel rods were exposed to the air, Kyodo news said.

A TEPCO spokesman later told AFP that the rods were covered again.

An explosion that destroyed the building around the No. 1 reactor at the same plant Saturday came despite the operator’s efforts to control high temperatures and growing pressure. - AFP/ Reuters