Friday, March 25, 2011

High-level radiation suspected to be leaking from No. 3 reactor's core | Kyodo News

High-level radiation suspected to be leaking from No. 3 reactor's core | Kyodo News: "TOKYO, March 25, Kyodo

High-level radiation detected Thursday in water at the No. 3 reactor's turbine building at the crisis-hit Fukushima Daiichi nuclear plant appears to have originated from the reactor core, the government's Nuclear and Industrial Safety Agency said Friday.

But no data, such as on the pressure level, have suggested the reactor vessel has been cracked or damaged, agency spokesman Hidehiko Nishiyama emphasized at an afternoon press conference, backing down from his previous remark that there is a good chance that the reactor has been damaged. It remains uncertain how the leakage happened, he added.

A day after three workers were exposed Thursday to water containing radioactive materials 10,000 times the normal level at the turbine building connected to the No. 3 reactor building, highly radioactive water was found also at the No. 1 and No. 2 reactors' turbine buildings.

The latest development in Japan's worst nuclear crisis raises the risk of more workers being exposed to radioactive elements, hampering their efforts to restore the plant's crippled cooling functions that are key to putting the crisis under control.

The three workers were transferred to the National Institute of Radiological Sciences in Chiba Prefecture Friday afternoon, after two of them were taken Thursday to a Fukushima hospital for possible radiation burns to their feet, the plant operator Tokyo Electric Power Co. said.

Following the incident, the nuclear regulatory agency ordered the utility known as TEPCO to improve radiation management at the power station, located about 220 kilometers northeast of Tokyo.

Nishiyama said the high-level radiation is suspected to have come from the reactor, where overheating fuel rods are believed to have partially melted.

He said further verification is needed to find out how the radioactive water reached the underground site where the workers were exposed. Huge volumes of water have been poured into the reactor as well as its apparently boiling spent fuel pool since they lost their cooling functions.

The government, which has set the exclusion zone covering areas within a 20 kilometer radius of the Fukushima plant, meanwhile, encouraged residents within a 30 kilometer radius of the power station to voluntarily leave, while the official directive is for them to stay indoors.

The Nuclear Safety Commission of Japan, a government panel, recommended voluntary evacuation as the release of radioactive materials from the plant is expected to continue for some time.

Despite the partial halt of restoration work due to the technicians' radiation exposure, TEPCO on Friday began injecting freshwater into the No. 1 reactor core, as it prepares to inject freshwater into all the troubled three reactor cores and four spent fuel pools, instead of seawater currently used.

As a step to bring the reactors under control, authorities are eager to replace seawater with fresh water in cooling the reactor cores and the pools, as crystallized salt could form a crust on the fuel rods and prevent smooth water circulation, thus diminishing the cooling effect.

Defense Minister Toshimi Kitazawa told a news conference Friday that U.S. forces in Japan will provide some freshwater to be sprayed at the fuel pools to ensure ample water supply. TEPCO currently uses freshwater from a dam near the plant.

Following the March 11 quake-tsunami disaster, the cooling functions failed at the No. 1, No. 2 and No. 3 reactors and their reactor cores partially melted at the plant on the Pacific coast, prompting seawater to be pumped in to prevent the fuel from being exposed.

The cooling functions of the pools storing spent nuclear fuel at the three units, as well as at the No. 4 unit, were also lost. The No. 4 reactor, halted for a regular inspection before the quake, has had all of its fuel rods stored in the pool for the maintenance work.

The nuclear agency said black smoke, which had been observed intermittently, stopped billowing from the No. 3 reactor building Friday morning, but that white smoke, possibly steam, is still seen rising from the No. 1, No. 2 and No. 4 units.


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