Restoration at nuke plant disrupted, radiation fears spread to Tokyo
TOKYO, March 23, Kyodo
Work to restore power and key cooling functions was disrupted again Wednesday at the crisis-hit Fukushima Daiichi nuclear plant as smoke caused workers to evacuate, while fear of radioactive pollution spread to Tokyo with an alert not to give tap water to infants.
Chief Cabinet Secretary Yukio Edano urged residents of areas under the wind from the plant to stay indoors and avoid exposure to air as much as possible as a precaution, while official advisories are for people within a 20-kilometer radius to evacuate and within 20 km to 30 km to stay indoors.
The plant operator Tokyo Electric Power Co. said it learned at around 4:20 p.m. that black smoke was seen rising at the No. 3 reactor building, leading to evacuation of workers from the four troubled reactors, but added about an hour later that it was receding.
The radiation level was unchanged shortly afterward, meaning the smoke caused no massive release of radioactive materials, the government's nuclear safety agency said. Smoke was also seen billowing from the No. 3 building on Monday.
It also turned out that the surface temperatures of the No. 1 and No. 3 reactor vessels have topped the maximum levels set by their designers. The rise of the temperatures came to light after data measuring instruments became available with the power restored Tuesday, the agency said.
In Tokyo, the metropolitan government said radioactive iodine exceeding the limit for infants' intake was detected in water at a purification plant, apparently due to the ongoing crisis at the power station crippled by the March 11 massive quake and tsunami.
At the plant run by the utility known as TEPCO, all six reactors were reconnected to external power as of Tuesday night and workers scrambled to check each piece of equipment, such as data measuring tools and feed-water pumps, before transmitting power to them.
As part of efforts to restore lost functions at the plant, TEPCO aimed to first revive a pump by Thursday to inject fresh water into the core of the No. 3 reactor, instead of seawater that has currently been poured using fire pumps, the Nuclear and Industrial Safety Agency said.
While the maximum vessel temperature set by the reactors' designers is 302 C degrees, the surface temperature of the No. 1 reactor vessel briefly topped 400 C and dropped to about 350 C by noon, and that of the No. 3 reactor vessel stood at about 305 C, the agency said.
Although the facilities are not expected to start melting at those temperatures, according to agency spokesman Hidehiko Nishiyama, TEPCO increased the amount of seawater injected into the No. 1 reactor by nine times to help cool it down.
Nishiyama said TEPCO will carefully continue to inject massive amounts of water into the No. 1 reactor so as not to raise the pressure in the reactor.
Massive water injection could raise pressure in the reactor, which increases the risk of damage to the facility, and workers would be required to release radioactive steam from the reactor to lower the pressure.
At the No. 2 reactor, workers have been unable to replace a pump to help revive its internal cooling system since Friday as high-level radiation amounting to at least 500 millisieverts per hour was detected at its turbine building, the spokesman said.
Water-spraying operations, meanwhile, continued in the morning at the No. 4 reactor unit to help cool down its spent nuclear fuel pool, using trucks with a concrete squeeze pump and a 50-meter arm capable of pouring water from a higher point.
But similar operations for the No. 3 reactor were put off due to the smoke.
Also on Wednesday, a series of strong aftershocks jolted the coastal area of Fukushima Prefecture where the crippled plant is located, but they did not affect the restoration work, the nuclear agency said.
TEPCO said two workers who had been installing a makeshift power source from Tuesday night were injured and taken to hospital, but they were not exposed to radiation.
Lighting in a control room for the No. 3 and No. 4 reactors was partially restored Tuesday night, a key step toward regaining control of the situation as operators have been unable to remain in any control rooms for long hours due to high radiation levels and power outages.
After the March 11 earthquake and massive tsunami knocked out power at the plant, the cooling functions failed at the No. 1, No. 2 and No. 3 reactors, while the pools storing spent nuclear fuel at the No. 1, No. 2, No. 3 and No. 4 units have also lost all their cooling functions.
In addition to efforts to douse the pools with water sprayed from outside, workers are also attempting to inject water by reviving internal cooling systems, according to the nuclear agency.
==Kyodo News