An explosion rocked a building housing a nuclear reactor at a quake-damaged Japanese power plant on Monday, the second such blast in two days, and the cooling system failed at a third reactor.
The new troubles at the Fukushima No. 1 plant, located 250 kilometres (120 miles) north of Tokyo, stalled Japan’s efforts to secure the atomic power facility in the wake of Friday’s massive quake and devastating tsunami.
Officials said the container surrounding the plant’s number-three reactor was not breached in Monday’s blast — which left 11 people injured — and there was no major rise in radiation levels.
A similar explosion hit the building housing the number-one reactor at the plant on Saturday, the day after a 8.9-magnitude earthquake generated a wall of water that swamped a large swathe of the country’s Pacific coast.
Chief government spokesman Yukio Edano also said the cooling system at the number-two reactor had stopped after the blast. Water levels were falling and workers were preparing to douse it with sea water, he said.
Jiji Press, quoting officials from plant operator Tokyo Electric Power Co (TEPCO), said officials are considering making a hole in the building to release hydrogen.
The earlier explosion was caused by a build-up of hydrogen in the number-three reactor building, Edano said, but pressure in the reactor remains stable.
“The soundness of the reactor container has been maintained,” he said. “The figures do not indicate a high level of radiation.”
Edano said 11 people were injured in the blast, one of them seriously and four of them slightly.
Officials who have been battling a possible partial meltdown are injecting sea water into the reactors to replace lost coolant — a procedure that will render the 40-year-old plant unusable.
Earthquake-prone Japan uses nuclear power to generate a third of its electricity.
The nuclear plants shut down automatically during a quake, but the loss of power in the area and tsunami damage to back-up generators apparently shut down cooling systems.
Authorities have declared an evacuation zone within a 20-kilometre radius of the plant and so far evacuated 210,000 people.
Nearly 750 people — patients, elderly people and care workers at three hospitals and nursing homes — remained within the zone on Monday.
“We have strongly advised all the people still within the evacuation area to go inside nearby facilities,” said nuclear safety agency spokesman Ryo Miyake.
A Fukushima official said 311 had so far been moved out.
Authorities have announced plans for scheduled rolling power cuts in areas served by TEPCO to make up for the loss of power from crippled nuclear plants. The company said phased blackouts were to have begun at 5:00 pm (0800 GMT).
Eleven of the country’s roughly 50 nuclear reactors, located in the worst affected areas, shut down following the earthquake.