A revised road map for ending the crisis at the Fukushima No. 1 nuclear power plant did not mention a Cabinet minister's new target for bringing the stricken reactors into cold shutdown.
A revised road map for ending the crisis at the Fukushima No. 1 nuclear power plant did not mention a Cabinet minister's new target for bringing the stricken reactors into cold shutdown.
Goshi Hosono, the state minister overseeing the Fukushima nuclear accident, said at a Sept. 19 meeting in Vienna of the International Atomic Energy Agency that Japan would reach cold shutdown by the end of the year, a few weeks earlier than initially planned.
But the revised road map, released Sept. 20, did not change the timing for the next stage of settling the Fukushima accident, which will last from mid-October until mid-January 2012.
"While we will not revise the period for achieving the objective, (Hosono's comment) means we want to make every effort to achieve the objective by the end of the year," Yasuhiro Sonoda, a parliamentary secretary at the Cabinet Office, said at a Sept. 20 news conference in Tokyo. "We will do our utmost on restoring operations."
Under the government's conditions for cold shutdown, the Fukushima reactors' temperatures must remain under 100 degrees and authorities must confirm that new radioactive materials are not being released.
The temperature at the No. 1 reactor was about 82 degrees on Sept. 20, while the No. 3 reactor had a temperature of about 88 degrees. The temperature at the No. 2 reactor was about 112 degrees, but officials plan to increase the volume of cooling water pumped into that reactor.
Workers have started operating new equipment to process water contaminated with radiation, which has reduced the pool of contaminated water on the reactor floors. A water-pumping system to effectively cool the No. 2 and No. 3 reactors has also been installed.
Officials have estimated that the amount of new radioactive materials released into the atmosphere from the reactors is now about 200 million becquerels per hour, about one-four-millionths the level immediately after the accident started on March 11.
The annual level of radiation at the entrance to the Fukushima plant was detected at 0.4 millisieverts, which is lower than the 1 millisievert objective for cold shutdown, according to officials.
While the central government has set the minimum conditions for cold shutdown, it has not yet formally set standards in determining if that state has actually been achieved.
The Nuclear and Industrial Safety Agency is expected to compile standards, including measures taken to continue safe cooling of the reactors, and will ask Tokyo Electric Power Co., the operator of the Fukushima plant, to submit a report.
The revised road map did not include any major additional measures to prevent the release of radioactive materials, except for attaching a filter on the containment vessels.
The government has also not yet decided on how achieving cold shutdown will affect decisions to change or reduce the no-entry zones within a 20-kilometer radius of the Fukushima plant. Such changes will be necessary to allow evacuees to return to their homes.
Among the issues that will have to be addressed to determine whether evacuation orders can be lifted are decontaminating the soil, rebuilding local administrative bodies and repairing social infrastructure necessary for residents to return to their homes.