Tokyo: Japan pumped nitrogen into a crippled nuclear reactor on Thursday, trying to prevent an explosive build-up of hydrogen gas, as the world’s worst nuclear disaster in 25 years fired debate over the safety of atomic power in the United States.
In a sign of growing international concern over radiation fall-out from the earthquake-wrecked Japanese plant, some schools in neighbouring South Korea closed because parents were worried that rain there might be toxic.
Latest data, meanwhile, showed that foreign tourists were shunning Japan during what would normally be one of the most popular seasons to visit the country.
Engineers have been working since Wednesday night to pump nitrogen gas into the containment vessel of reactor No.1 at the Fukushima Daiichi power plant, which was smashed by a 10-metre tsunami that followed the massive earthquake of 11 March.
An official at plant operator Tokyo Electric Power (Tepco) insisted that it was a precautionary measure and the chances were “extremely small” of a repeat of hydrogen gas explosions that ripped through two reactors early in the crisis.
But while the government says the situation has stabilised at the devastated plant, 240 km north of Tokyo, it is still far from under control.
“Data shows the reactors are in a stable condition, but we are not out of the woods yet,” Chief Cabinet Secretary Yukio Edano told reporters.
One Tepco official said 6,000 cubic metres (212,000 cubic feet) of nitrogen gas would be pumped into reactor No.1 and the utility was preparing gas injections for reactors No.2 and No.3 in the six-reactor plant as a safety precaution .
Engineers did manage on Wednesday to finally plug a leak at reactor No.2, but they still need to pump 11.5 million litres (11,500 tonnes) of contaminated water back into the ocean because they have run out of storage space at the facility. The water was used to cool overheated fuel rods.
Workers are struggling to restart cooling pumps -- which recycle the water -- in four damaged reactors.
Until those are fixed, they must pump in water to prevent overheating and meltdowns, but have run out of storage capacity for the seawater when it becomes contaminated.
In Vienna, the head of a UN scientific body said based on the information he had now, the Fukushima accident was not expected to have any serious impact on people’s health.
Wolfgang Weiss, chairman of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), said the Fukushima disaster was less dramatic than Chernobyl in 1986 but “much more serious” than Three Mile Island in 1979.
“We have seen traces of iodine in the air all over the world now but they are much, much, much lower than traces we have seen at similar distances after Chernobyl,” he added.
Neighbouring South Korea and China, however, are worried about radioactive fallout. China’s health ministry found traces of radioactivity in spinach in three Chinese provinces and South Korean media have reported fears about contaminated rainfall.
In South Korea, some schools closed because of worries the rainfall across the country could be contaminated. The country’s nuclear safety agency said a small level of radioactive iodine and caesium particles was reported in the south but was not enough to cause public health concern.
Latest data shows that the number of foreigners coming to Japan had plunged by 75 percent since the crisis struck.
In Washington, Democratic lawmakers raised concerns, in the wake of Japan’s crisis, about whether regulators and the nuclear power industry were doing enough to ensure US reactors could withstand worst-case scenarios in the wake of Japan’s crisis.
Concerns focused on a Pennsylvania nuclear plant with the same kind of reactor design as the Fukushima facility.
Some lawmakers argued that the US plant could be at risk of meltdown in the case of a severe emergency.
But Martin Virgilio, a top official for the US Nuclear Regulatory Commission (NRC), told a congressional hearing that the NRC did not believe that the core of Fukushima’s reactor No. 2 had melted down.
Earlier, a Democratic lawmaker had said the NRC informed him the core had become so hot it had probably melted through the reactor pressure vessel.
The NRC is conducting special inspections at two Illinois nuclear plants operated by Exelon Corp after routine checks in February found a problem with backup pumps that would be used to remove heat from the reactors in case of an accident.