Efforts to stabilize reactors at the quake-stricken Fukushima No. 1 nuclear power plant are at "Step 2" of a road map designed to end the crisis.
Efforts to stabilize reactors at the quake-stricken Fukushima No. 1 nuclear power plant are at "Step 2" of a road map designed to end the crisis.
Five full months have passed since disaster flared following the March 11 Great East Japan Earthquake.
The government and Tokyo Electric Power Co. (TEPCO), operator of the plant, are aiming to bring the nuclear reactors to a cold shutdown so that residents evacuated from areas close to the facility can return to their homes.
Major challenges include stabilizing the treatment of radioactive water and suppressing the discharge of radioactive material from the containment vessels.
The target completion time for Step 2, which includes bringing the nuclear reactors to a cold shutdown, is between October and January. The evacuated residents will be able to return home only after Step 2 is completed.
Under the process, temperatures in the reactors' pressure vessels must be brought down to below 100 degrees, conditions that define a cold shutdown. This has been accomplished at the No. 1 reactor, but temperatures in the No. 2 and No. 3 reactors continue to hover at between 104 and 117 degrees.
The volume of water being pumped into the reactors to cool them is being curtailed to prevent an increase in the amount of radioactive water that remains at the plant.
A succession of glitches at the purification plant for radioactive water, and consequent delays in its treatment, are key factors in the delay to stabilize the reactors.
The water purification plant operated at 66.4 percent of designed capacity during the period through Aug. 9, according to an announcement by TEPCO the following day.
It said 120,240 tons of radioactive water remain at the nuclear facility, including at the reactor buildings. An earlier plan to get rid of most of the radioactive water by the end of December will likely be delayed, TEPCO said.
The cooling system for spent fuel storage pools was restored ahead of schedule at the No. 2, No. 3 and No. 4 reactors. It also entered full operations at the No. 1 reactor on Aug. 10.
Hydrogen explosions occurred at all four reactors soon after the quake.
(This article was written by Naoya Kon and Takashi Sugimoto.)