Workers enter Fukushima reactor building for first time since disaster

The magnitude 9.0 quake and massive tsunami that followed killed about 14,800 people,left some 11,000 missing and destroyed tens of thousands of homes.

It also knocked out all the cooling systems at the Fukushima plant,240 km north of Tokyo,leading to the greatest leak of radiation since the 1986 Chernobyl disaster.

Two TEPCO staff and 10 contractors with protective suits,masks and air tanks worked for 1-1/2 hours,moving in and out in small groups to connect duct pipes to ventilators that will filter out 95 per cent of the radioactive material in the air,a spokesman said.

“We will operate the (ventilators) for two or three days. After that we plan to start work on actually installing the cooling system,” spokesman Naoyuki Matsumoto said.

The nuclear safety agency later said the ventilator system and filters were running.

TEPCO said the workers who did the work were expected to have been exposed to about 3 millisieverts of radiation each in the operation. Under Japanese law,nuclear plant workers cannot be exposed to more than 100 millisieverts over five years,but to cope with the Fukushima crisis,the Health Ministry raised the legal limit on March 15 to 250 millisieverts in an emergency.

Radiation of up to 49 millisieverts per hour was detected inside the building on April 17 when TEPCO sent in a robot to survey conditions.

Matsumoto could not give details of the 10 contractors’ employment conditions,but he said they were bound by the same 250-millisievert limit for exposure to radioactivity as all other staff at the beleaguered plant.

TEPCO also said in a report issued to the nuclear safety agency on Thursday that there was no possibility of another hydrogen explosion at the No.1 reactor due to progress in filling the containment vessel,an outer shell of steel and concrete that houses the reactor vessel,with water.

Workers have been trying to fill the reactors with enough water to bring the nuclear fuel rods inside to a cold shutdown,in which the water cooling them is below 100 degrees Celsius and the reactors are considered stable.

If the nuclear safety agency approves the TEPCO report,the company said it would increase the rate at which it is pumping in water to speed up the process.