SENDAI, Japan, March 28, 2011 (AFP) - Japan Monday criticised as "absolutely unacceptable" a radiation reading error by the operator of a crippled atomic plant, where dangerous conditions have disrupted crucial work for two days.
Work has been halted at reactor two of the Fukushima plant that is at the centre of Japan's cascading disaster -- an earthquake that sparked a tsunami which in turn triggered the world's worst nuclear emergency since Chernobyl.
Radiation from the plant northeast of Tokyo has wafted into the air, contaminating farm produce and drinking water, and seeped into the Pacific Ocean, although officials stress there is no imminent health threat.
Engineers are racing to restore cooling systems knocked out by the tsunami, but fear that radiation has already escaped, either through leaks in the steel-and-concrete reactor casings or their pipe systems.
Embattled operator Tokyo Electric Power Company (TEPCO) doesn't know for sure what happened inside three reactors after explosions ripped away or damaged their outer buildings, designed as the final barrier to the atmosphere.
The company came under fire Monday, a day after it erroneously said radiation in water at the stricken site had reached 10 million times the normal level, later issuing a much lower -- but still dangerous -- figure.
"Considering the fact that the monitoring of radioactivity is a major condition to ensure safety, this kind of mistake is absolutely unacceptable," said top government spokesman Yukio Edano.
Reports the same day said TEPCO's president, 66-year-old Masataka Shimizu, fell sick on March 16 and took a week off from the joint task force with the government set up to handle the crisis, although he has now returned to work.
At a press conference Monday, TEPCO officials for the first time mentioned the possibility that the core pressure vessels of reactors one, two and three may all be damaged, Jiji Press news agency reported.
Telltale signs of nuclear fission -- radioactive iodine-131, caesium-137 and other isotopes -- have been detected in water that has flooded the basements of the three reactors' adjacent turbine buildings, halting work there.
Two workers, unidentified men in their 20s and 30s employed by a TEPCO subsidiary, were hospitalised last week after wading though the water with inadequate protection. They are expected to be released Monday.
TEPCO has faced heavy criticism for not briefing the workers sufficiently before sending them on their dangerous mission which saw the two men sloshing through the pool without full-length boots.
Work at reactor two has been temporarily halted since Sunday because of the danger. The immediate focus is on draining the highly radioactive water from the turbine room basements, but without releasing it into the environment.
The water inside the reactor two turbine room was Sunday measured at 1,000 millisieverts an hour -- a dose that can cause temporary radiation sickness with nausea and vomiting for people who are exposed.
Pacific Ocean seawater just north of the plant was found to have 1,150 times the legal limit of iodine, the nuclear safety agency said Monday. Previous readings to the south reached more than 1,850 times the legal limit.
The nuclear crisis remains a distraction from the dire plight of hundreds of thousands made homeless by the quake-tsunami disaster that has left nearly 30,000 people confirmed dead or listed missing.
Hundreds of aftershocks since the March 11 disaster have rattled buildings and further strained nerves -- including a powerful 6.1-magnitude quake that sparked a tsunami advisory in worst-hit Miyagi prefecture early Monday.
In areas near the nuclear plant -- some of them virtual ghost towns with people holed up in their homes -- rubble remained uncleared and tsunami victims have received little aid because supplies have ground to a halt.
The Japanese government has ordered people to leave the area within 20 kilometres (12 miles) from the stricken plant and "encouraged" people to move out of places 20-30 kilometres away.
Environmental activist group Greenpeace said it had confirmed radiation levels of up to 10 microsieverts per hour in Iitate village, 40 kilometres northwest of the plant, and urged the government to evacuate the area.
"It is clearly not safe for people to remain in Iitate, especially children and pregnant women, when it could mean receiving the maximum allowed annual dose of radiation in only a few days," said its radiation safety expert Jan van de Putte.
"The authorities must stop choosing politics over science and determine evacuation zones around the Fukushima nuclear plant that reflect the radiation levels being found in the environment."
