The amount of radioactivity leaking from the damaged Fukushima No. 1 nuclear power plant has fallen dramatically after an opening at one of the reactors was sealed shut.
The amount of radioactivity leaking from the damaged Fukushima No. 1 nuclear power plant has fallen dramatically after an opening at one of the reactors was sealed shut.
Earlier this month, measurements showed that about 10 million becquerels of radioactive substances per hour were being released into the atmosphere from the No. 1, No. 2 and No. 3 reactor buildings, where core meltdowns had taken place, about one-seventh the discharge rate in January.
The findings were reported at a meeting on Feb. 27 between the central government and Tokyo Electric Power Co. to discuss mid- to long-term measures toward an eventual decommissioning of the nuclear plant.
Most of the radioactive substances were being released from the damaged No. 3 reactor building, which remains uncovered since its roof was blown off by a hydrogen explosion on March 14. The No. 1 reactor building was also damaged by a hydrogen explosion, but a cover is blocking the discharge of radioactive substances.
The release of radioactive materials decreased partly because the freight entrance for large-size material at the No. 3 reactor building, which was damaged and left open by the tsunami, was sealed to prevent potential leaks of radioactive water from frozen pipes within the building.
The measure helped block the flow of air from the entrance toward the damaged ceiling and roof of the reactor building, the government and TEPCO said.
Meanwhile, TEPCO said new equipment will be installed by September that will purify radioactive water to levels that are safe for discharge into the ocean.
At the meeting, TEPCO demonstrated the results of basic tests of the "ALPS" multinuclide removal equipment, which is a water purification system manufactured by Toshiba Corp. The current operational purification equipment mostly eliminates cesium only. The ALPS system will also eliminate nuclides other than cesium.
During the tests, the ALPS equipment successfully reduced 45 gamma nuclides to concentrations below legally tolerable levels for discharge into the ocean.
TEPCO has said, however, that decisions will be made to release purified water into the sea only if understanding is obtained from local governments and fishermen's unions.
Elsewhere, the interior of the containment vessel at the No. 2 reactor will be inspected for the second time in early March using an industrial endoscope as part of preparations for an eventual decommissioning.
By using a cable that is longer than the one used during the previous inspection on Jan. 19, the government and TEPCO hope to measure the level of water in the containment vessel that they failed to measure on the previous occasion.