TOKYO— Scrambling to corral a widening crisis, engineers linked a power cable to the crippled Fukushima Daiichi Nuclear Power Station early Saturday as they struggled to restart systems designed to prevent overheating and keep radiation from escaping.
The Tokyo Electric Power Company, which runs the plant, said it hoped to connect the electric cord to the cooling equipment inside the facility later Saturday in an attempt to stabilize the reactors that were damaged by the powerful earthquake and tsunami that struckJapaneight days ago.
In a brief statement on Japanese television Saturday morning, an official for Japan’s Nuclear and Industrial Safety Agency said that workers had managed to restart a diesel pump and restored cooling functions at two of the reactors, Nos. 5 and 6, early Saturday morning. He did not provide any details.
Those reactors were not in use when the disaster occurred, but they contained spent fuel rods, and engineers were concerned this week when temperatures in the reactors began to rise.
About 150 of its people were working on the electrical cable, the power company said, and they were planning to start with Reactor No. 2, which on Friday was seen spewing steam, perhaps containing radioactive particles.
Officials have cautioned, however, that restoring electricity to the reactor would prove fruitless if the pumps were not working. In that case, a new cooling system would be needed, leading to more delays in an emergency that has bedeviled the power company and the government and caused anxiety and frustration overseas.
The nuclear safety agency said that the crisis now had wider consequences, and raised its assessment of the accident’s severity to Level 5 on a seven-level scale established by theInternational Atomic Energy Agency. Hidehiko Nishiyama, a senior official at the agency, said the assessment was retroactive to Tuesday and based on the fact that officials now assumed that more than 3 percent of the nuclear fuel at the plant had experienced meltdown.
The adjustment was an admission by Japanese officials that the problem was worse than it had previously stated.“We could have moved more quickly in collecting information and assessing the situation,” said Yukio Edano, the chief cabinet secretary.
Outside experts have said for days that this disaster is worse than the one in 1979 at Three Mile Island— which the United States classified as a 5 on the international scale but which released far less radiation outside the plant than Fukushima Daiichi already has.
Engineers are starting the power cord effort with Reactor No. 2 because its outer building has not blown off, thus making it hard to spray in water the way they can with Nos. 1, 3 and 4, according to NHK, Japan’s national broadcaster, which cited power company officials.
The plan was to lay a 1.5-kilometer power cable between Reactor Nos. 1 and 3 to get to No. 2. If they can hook it up, it will theoretically be able to power all six reactors. The main hazard was the exposure of workers.
Unable to contain the catastrophe on its own, Tokyo Electric has received help from Japanese police and fire departments and the country’s Self-Defense Forces. Assistance has started to flood in as well, with nuclear experts arriving from the United States and international agencies. France and South Korea are also providing support.
Overnight in Japan, crews from the Tokyo Fire Department doused water on Reactor No. 3, which was doused earlier Friday by teams from the Self-Defense Forces and the United States military. Workers planned to continue the spraying on Saturday.
In a further sign of spreading alarm on Friday that uranium in the plant could begin to melt, Japan planned to import about 150 tons of boron from South Korea and France to mix with water to be sprayed onto damaged reactors, French and South Korean officials said Friday. Boron absorbs neutrons during a nuclear reaction and can be used in an effort to stop a meltdown if the zirconium cladding on uranium fuel rods is compromised.
Tokyo Electric Power said this week that there was a possibility of“recriticality,” in which fission would resume if fuel rods melted and the uranium pellets slumped into a jumble on the floor of a storage pool or reactor core. Spraying pure water on the uranium under these conditions can actually accelerate fission, said Robert Albrecht, a longtime nuclear engineer.
Nuclear reactions at the plant were halted immediately after last week’s 9.0-magnitude earthquake and before the tsunami arrived minutes later.
Комментариев нет:
Отправить комментарий