tsunami waves from the air, water contaminated
See the first minute or so of of this clip to view the tsunami swells produced by the earthquake as they approach the land, as filmed from a helicopter (what was the pilot thinking?)
The 9.0-magnitude quake and ensuing tsunami on March 11 devastated Japan’s north-eastern Pacific coast, knocking out the Fukushima nuclear reactor plant’s cooling systems and leaving it on the brink of a catastrophic meltdown. It was the biggest earthquake to hit Japan since records began in the 1800s. Helicopters and fire trucks have been deployed to pour water over heating fuel rods at the plant since Thursday.
In a desperate attempt, workers have used fire engines to hose thousands of tons of seawater onto the plant in a bid to keep the fuel rods inside reactor cores and spent fuel pools from being exposed to the air, where they could reach critical stage and go into full meltdown.
New safety worries have further complicated efforts to bring the ageing facility under control and raised fears that the fuel rod vessels or their valves and pipes are leaking. Officials have said some sprayed or dumped water may have spilled back into the sea.
Updated article from ABC Science here – and summary of TEPCO statements and more over the jump.
Urgent efforts are underway to drain the pools after several workers suffered radiation burns while installing cables as part of efforts to restore the critical cooling systems.
“Highly radioactive water is flowing inside the buildings and then into the sea, which is worrying for fish and marine vegetation,” said Olivier Isnard, an expert at France’s Institute for Radiological Protection and Nuclear Safety.
“One hypothesis is that the reactor vessel is breached and highly radioactive corium is coming out.”
Abnormally high levels of radioactive substances have been detected in seawater near the Fukushima plant. The substances were sampled about 100 metres south of the facility, a Tokyo Electric Power Co. (TEPCO) official said, initially stressing it was not a threat to human health.
“Normally, such radioactive substances are not detected in the area,” said Naoki Tsunoda, a Tokyo Electric Power Co. (TEPCO) official, adding that the company will continue monitoring at the same point and in other areas.
Several hundred metres offshore in the Pacific Ocean, levels of iodine-131 about 1,250 times the legal limit were detected on Saturday, plant operator Tokyo Electric Power Co (TEPCO) said.
Mr Nishiyama, an official at the nuclear safety agency, said drinking a 500ml litre bottle of fresh water with the same concentration would expose a person to their annual safe dose.
Officials insist there is minimal risk to humans and marine life.
“Generally speaking, radioactive material released into the sea will spread due to tides, so you need much more for seaweed and sea life to absorb it,” Mr Nishiyama said.
Because iodine-131 decays relatively quickly, with a half-life of eight days, “by the time people eat the sea products, its amount is likely to have diminished significantly,” he said.
However, TEPCO also reported levels of caesium-137 – which has a half life of about 30 years – almost 80 times the legal maximum. Scientists say both radioactive substances can cause cancer if absorbed by humans.
TEPCO says the level of iodine-131 is 126.7 times higher and caesium-134 is 24.8 times higher than government-set standards.
The company has confirmed power cables have been connected to all six nuclear reactors at the stricken power plant. However some workers were evacuated on Saturday from the Fukushima nuclear plant after exposure to a massively high spike in radiation, plant operator TEPCO said. There are reports this has already subsided, although the current levels are about one and a half times higher than before the spike.
Last Wednesday Tokyo residents were warned not to give babies tap water because of radiation leaking from the Fukushima plant. Panic buying has seen many shops stripped of bottled water.
The high radiation results in tapwater “undoubtedly results from the Fukushima nuclear plant accident. We just don’t know the details as to how we got this high level,” said the manager of Tokyo’s Waterworks Bureau.