The painstaking task of restoring external power to the crippled reactors at the Fukushima No. 1 nuclear power plant continued on Monday, despite high radiation levels that are hindering some parts of the emergency operation.
The painstaking task of restoring external power to the crippled reactors at the Fukushima No. 1 nuclear power plant continued on Monday, despite high radiation levels that are hindering some parts of the emergency operation.
The plant's operator, Tokyo Electric Power Co. (TEPCO), said the No. 2 reactor was connected to an external electricity cable at 3:46 p.m. Sunday.
The No. 5 reactor switched over to an external power source on Monday and efforts are continuing to connect electrical cables to the No. 3 to No. 6 reactors. The No. 5 and No. 6 reactors have been using emergency generators since Saturday.
An approximately 1.5-kilometer-long electrical cable was connected from power transmission lines to the distribution board within the turbine building of the No. 2 reactor on Saturday.
TEPCO officials were checking for equipment malfunctions, electrical leaks, and problems with wiring before switching on the power to the central control room of the No. 2 reactor. If that control room gets external power, lights and instruments that monitor the reactor might be available to the teams struggling to stabilize the plant.
A TEPCO official said: "If we can use the control panel in the central control room, we would be able to analyze the condition of the equipment and determine where abnormalities were occurring."
Cables have been laid to the No. 5 and 6 reactors and external power was connected to the No. 5 reactor on Monday afternoon.
TEPCO officials said Sunday that the No. 5 and No. 6 reactors had reached the cold shutdown stage, meaning that the temperature of the reactor cores had fallen below 100 degrees. Both reactors had been stopped for routine inspections when the Great East Japan Earthquake hit on March 11.
Emergency generators were connected to the two reactors from Saturday, restoring vital cooling functions.
Work was also continuing on Monday to connect a different power transmission line to the No. 3 and No. 4 reactors. That part of the operation is being hindered by high radiation levels near the two reactors.
Although radiation levels within the Fukushima plant increased sharply on March 16, when white smoke was observed spewing from the No. 3 reactor, levels have not risen dramatically since then.
TEPCO officials announced Monday that levels of iodine-131 of six times the official limit had been measured. Cesium was also detected.
On Sunday night, the Nuclear and Industrial Safety Agency said iodine and cesium had been detected in airborne dust within the immediate area of the Fukushima plant.
Iodine and cesium are produced during nuclear fission and their presence is evidence that fuel rods in the reactor cores or spent fuel rods kept in storage pools have been damaged.
Defense Ministry officials said the Self-Defense Forces began spraying water on the No. 4 reactor from around 6:30 a.m. Monday. Twelve SDF fire trucks and one loaned from the U.S. military were used for the operation. TEPCO workers operated the U.S. military fire truck.
A total of about 90 tons of water was sprayed. On Sunday, two water spraying operations dumped about 160 tons of water on the No. 4 reactor.
On Saturday, Sunday and Monday, the Tokyo Fire Department hosed the No. 3 reactor using trucks that can spray water from 22-meter articulated arms at a rate of about 3 tons a minute. The firefighters pumped seawater through about 800 meters of hose to the plant.
The operation began Saturday afternoon and continued for about 13 hours until 3:40 a.m. Sunday. A total of about 2,430 tons of water was sprayed. It resumed on Sunday night and continued into Monday.
The storage pool for spent fuel rods in the No. 3 reactor has a capacity of about 1,000 tons. Even if it was empty at the start of the operation, it is believed that enough water was pumped onto the reactor to fill that pool.
The SDF sent helicopters over the Fukushima plant facility on Saturday and Sunday to measure temperatures.
Defense Minister Toshimi Kitazawa said Sunday night: "The water temperatures in the storage pools for spent fuel rods had all fallen below 100 degrees. Although the temperature above the No. 3 reactor containment vessel was 128 degrees, that was within the range expected by experts above the reactor core."