Government officials are scrambling to devise emergency measures--including covering damaged reactor buildings and using robots--to deal with radioactive materials that have hindered work at the crippled Fukushima No. 1 nuclear power plant.
Government officials are scrambling to devise emergency measures--including covering damaged reactor buildings and using robots--to deal with radioactive materials that have hindered work at the crippled Fukushima No. 1 nuclear power plant.
A wider range of options for the nuclear crisis is being considered because plant operator Tokyo Electric Power Co. is struggling to bring the situation under control and public concerns are rising about radiation spreading into the environment, sources said.
The presence of radioactive substances in and around the Fukushima plant has slowed work to restore mechanisms that can cool the reactor cores.
One measure under discussion is spraying a special paint over radioactive materials attached inside the No. 1 to No. 4 reactor buildings and then using a special canvass structure to cover the No. 1, No. 3 and No. 4 reactor buildings, which have been damaged by hydrogen explosions.
That plan could prevent radioactive materials from spreading through the air.
A ventilation system with filters would be attached because of the danger of another explosion of hydrogen accumulating under the air-tight canvass structure.
Another measure under discussion would involve filling an empty tanker anchored at the harbor adjacent to the Fukushima No. 1 plant with highly contaminated water leaking into the basement of the turbine buildings of the No. 2 and other reactors.
Pumps would be used to remove the radioactive water from the buildings.
Removal of the hazardous liquid would allow work to continue to restore power and the pumps needed to cool the reactor core and reduce the risk of radioactive water overflowing into the ocean.
However, officials of the Ministry of Land, Infrastructure, Transport and Tourism have raised concerns about the lack of docking facilities in the area for a large tanker. Other officials opposed the plan due to concerns about the safety of workers who would be asked to pump the water from the plant.
Also under discussion is the use of robots and remote-control operating equipment because of the limits to what the workers can do amid the high radiation levels.
Sources said the Japanese government has asked the business sector and the U.S. government for cooperation in the use of robotics.
Sumio Mabuchi, the former infrastructure minister, was appointed special adviser to Prime Minister Naoto Kan to deal with the nuclear accident at the Fukushima No. 1 plant.
Mabuchi and another special adviser, Goshi Hosono, have set up a team that includes officials from related government ministries, the Nuclear Safety Commission of Japan, TEPCO, electric equipment manufacturers and construction companies. Representatives of the U.S. Nuclear Regulatory Commission are also taking part.
Three subcommittees have been established within the special team to separately consider measures to seal in the radioactive materials, use remote control equipment, and remove and transfer the nuclear fuel rods.
The last subcommittee is considering what steps to take should the buildings housing the reactor cores collapse.
TEPCO is now taking a more accurate approach concerning water levels in the reactors to prevent radioactive water from overflowing and leaking outside the turbine buildings.
Workers are carefully calculating how much water is being pumped into the cores so that it theoretically equals the volume of water evaporating in the core.
Company officials said Wednesday morning the temperature of the No. 1 reactor core had fallen to 281.2 degrees as of 4 a.m. Early Tuesday morning, the temperature exceeded 320 degrees, forcing TEPCO workers to increase the volume pumped into the core by 30 percent to about 140 liters per minute.
A TEPCO official at the local Fukushima office said the temperatures had stabilized.
According to calculations made by the Kyoto University Reactor Research Institute, the decay heat of fuel rods in the core is causing water to evaporate at a rate of between 80 and 140 liters a minute.
The heat in the core will only decrease by half after six months and will continue to give off one-third of the heat after a year, the institute said.