Tokyo's main electric power company is preparing to send workers inside a crippled nuclear reactor to begin rebuilding the unit's cooling system. Power company officials say a ventilation system has lowered radiation levels in the reactor building damaged in March by a massive earthquake and tsunami.
The Tokyo Electric Power company is to open the doors on the Fukushima Daiichi Reactor 1 containment vessel, the thick concrete shell around the reactor core.
Its air has been so radioactive, a worker could be exposed only five hours before exceeding a safe limit. But an air filtration system installed Thursday has brought radiation down to a high, but more acceptable, level.
Workers are scheduled to enter it as early as Monday.
Once inside, staff will be checking pipes, valves and machinery to see what needs to be repaired so the reactor's self-cooling system can be put back in use.
Its failure has forced emergency crews to dump thousands of tons of water on the reactor to keep it cool, but that has created a large amount of radioactive waste water. The reactor cooling system re-circulates water, so its return would simplify recovery operations.
Opening the airlock doors will result in the release of some radioactive radiation, but Tokyo Electric said it will not be at a level that will cause concern to anyone beyond the 20-kilometers exclusion zone around the plant.
Goshi Hosono, a Japanese Government spokesman, says the Japanese government has notified nearby countries of the plans to release radioactive air, but it concurs that there will be no impact on the environment.
In a related matter, Tokyo Electric reported a sharp rise in temperature at the nearby Reactor 3. It was at 202 degrees Celcius early Sunday, up 40 degrees in less than a day, but still less than the normal operating temperature. Tokyo Electric plans to monitor the reactor closely.