The Japanese government on Sunday allowed the operator of the damaged Fukushima nuclear plant to open the doors of its reactor, but traces of radioactive material are expected to leak out, dpa reported.
The government's Nuclear and Industrial Agency and the operator, Tokyo Electric Power Co (TEPCO), said the move would not impact the environment.
The Fukushima Daiichi nuclear plant was crippled by a magnitude-9 earthquake and tsunami on March 11. The plant has leaked radioactive substances into the air and sea ever since.
TEPCO said the levels of radiation inside the building of reactor 1 was low, so opening the doors would not create problems. It informed local governments about the plan after getting the agency's approval. The government also informed other countries about the plan.
TEPCO said that even if radioactive substances are released from the building, the radiation dose within the plant's premises would be well below 1 millisievert - the level a person is normally exposed to annually, Kyodo News reported.
It was to allow workers to enter the building at about 4 am on Monday (1900 GMT Sunday) to measure the levels of radioactivity inside, Kyodo reported.
On Thursday, workers placed pipes connecting the building of reactor 1 with a ventilator to filter out radioactive substances to reduce the high radiation levels, so that workers could enter the site without the risk of exposure.
After measuring radiation levels in the air coming out of the building, TEPCO determined that it could open the doors that connect the reactor building with an adjacent turbine building.
Workers will now be able to go in and start to place a new cooling system for the reactor. High levels of radiation have prevented workers from restoring key cooling functions for the reactors.
Meanwhile, the temperature of the pressure vessel in reactor 3 had started to rise again - measuring 202 degrees Celsius in its upper section early Sunday, from 163 degrees on Saturday morning. During normal operations, the temperature is about 286 degrees, Kyodo reported.
The government has also decided to allow the fisheries industry to operate in waters beyond a 30-kilometre radius from the plant.