According to a United States researcher who surveyed waters off the site Tokyo Electric Power Company’s (TEPCO) claim that radioactive water leaking into the sea from the wrecked Fukushima nuclear plant is confined to the coast doesn’t make scientific sense.
Japan’s government has supported the utility’s statement that the irradiated groundwater flowing into the Pacific Ocean at a rate of some 400 tonnes a day remains in an area of 0.3 square kilometres within the bay fronting the nuclear power station.
“These statements like a 0.3 square-kilometre zone are silly,” Woods Hole Oceanographic Institution senior scientist Dr Ken Buesseler said in an interview with Bloomberg newsagency.
“It’s not true to the science,” said Dr Buesseler, who was on a Japanese research vessel one kilometre off Fukushima for a week in mid Sept.ember.
The growing stockpile of radioactive water stored in tanks at the plant and leaks from the tanks into the sea is an increasing threat to ocean ecosystems, said Dr Buesseler,
Dr Bruesselr holds a joint PhD in marine chemistry from the Massachusetts Institute of Technology and Woods Hole.
Founded in 1930, Woods Hole is the world’s largest private non-profit oceanographic research institution, according to its website.
Bloomberg reports the Fukushima power station has more than 1000 tanks holding more than 380,000 tonnes of water irradiated from contact with melted reactor fuel.
Three hundred tanks are of a bolted variety, at least one of which leaked about 300 tonnes of water.
Additional contaminated groundwater has been seeping into the Pacific Ocean and one of the tanks overflowed last week.
Each tank contained about 10 terabequerels, or 270 curies, of strontium-90, a radioactive element linked to leukemia that can enter the food chain by depositing into the bones of fish, Dr Buesseler said.
That is 100 times the amount of radioactivity dumped by Russia into the Sea of Japan in a 1993 incident that prompted international rules against ocean disposal.
“If only 10 of those tanks leaked it would equal all the strontium released in 2011” after the earthquake and tsunami, Dr Buesseler said.
“Once strontium gets into fish, it stays in them for months and years and it’s going to be an additional reason why they won’t be able to open up their fisheries.”
“One hundred kilometres away I can measure isotopes of cesium that are coming from the reactor” in Fukushima, Dr Buesseler said.
“They’re not at dangerous levels. The scientific question is are they at levels high enough to accumulate in the food chain and a cause for some of the fish to be above the legal limit.”
TEPCO’s own monitoring data show radiation levels beyond the immediate area around the plant to be “limited,” said spokesman Yoshikazu Nagai.
He added that the company recognised the importance of carefully managing contaminated water in storage at the site.
“We recognise that tank management is one of our most important issues so will continue making efforts to control contaminated water,” he said.
Bloomberg reports last month, South Korea banned imports of marine products from water off Fukushima and adjacent prefectures, citing public health concerns.
Japanese officials at the International Atomic Energy Agency in Vienna tried to assuage global concern over the impact of Fukushima’s radiation last month.
“The effect of the contaminated water is limited to the 0.3 square kilometres just within the port outside of the plant,” said Japan’s science and technology minister, Ichita Yamamoto.
“The credibility problem is as great as the engineering solution,” said Dr Buesseler, who has travelled to Japan multiple times to assess Fukushima’s impact on the ocean ecosystems.
“There’s a lack of trust that they keep reinforcing by saying things like ‘beyond this 0.3 kilometres zone there’s no release.’”
“There’s a lot of radioactivity stored on site in tanks,” said Dr Buesseler, adding that he’s concerned that even a small earthquake could trigger another crisis.
“All of those tanks are connected by pipes to each other and those pipes and those fittings are not earthquake proof.”
Lab results from his most recent visit should be published by February 2014, Dr Buesseler said.
