Radioactive material from Fukushima plant coming back to Japan in the Pacific — Fukushima Diary

” Prof. [Michio] Aoyama from [the] Institute of Environmental Radioactivity of Fukushima University reported that the radioactive material discharged from Fukushima plant circulated in the Pacific to come back to Japan offshore.

He implemented seawater analysis at 71 points from 11. 2015 to 2. 2016. The analysis is partially completed to show radioactive material has spread to the South West offshore of Japan. 2 Bq/m3 of Cs-137 was detected in seawater from South West offshore of Kyushu. 1.83 Bq/m3 was detected even offshore of the west coast of Japan.

0.38 Bq/m3 of Cs-134 was also measured to prove this is from Fukushima accident.

It is assumed that the discharged Cs-134/137 travelled to the east in the Northern Pacific. It was carried to the South and West to come back to Japan by taking 2 ~ 3 years.

He comments it is possible that the density of radioactive material increases from now. ”

Prof. Aoyama’s report: http://www.asyura2.com/16/genpatu45/msg/611.html

by Fukushima Diary

source

800 tera bq of cesium-137 to reach West Coast of North America by 2016: researcher — Shanghai Daily

” TOKYO, April 30 (Xinhua) — About 800 tera becquerel of Cesium- 137 is going to reach West Coast of North America by 2016, equivalent to 5 percent of the total Cs-137 amount discharged to the pacific ocean after the Fukushima nuclear disaster, a Japan researcher was quoted by Kyodo recently.

Michio Aoyama, a professor from Japan’s Fukushima University Institute of Environmental Radioactivity said about 3,500 tera bq of Cs-137 have been released to the sea and 1.2 to 1.5 tera bq of Cs-137 released to the air, then fell to the sea from the crippled nuclear plant.

Part of the radioactive substances have been observed to move eastward at a speed of 7 kilometers and 3 kilometers one day before March and August 2012 respectively, Aoyama said.

However, Cs-137 levels detected at U.S. beaches were 1 to 2 bq per cubic meter, much lower than the safety limit for cesium levels in drinking water by the World Health Organization.

“Even if all the 800 tera bq Cs-137 have arrived, the radiation levels will stay at relatively low level that aren’t expected to harm human health,” said Aoyama.

The Woods Hole Oceanographic Institution of America has announced early April that they detected Cs-134 for the first time in a seawater sample from the shoreline of North America. Cs-134, with a half-life of only two years, is an unequivocal marker of Fukushima ocean contamination, said researchers. ”

source

Fukushima’s cesium-137 levels ‘50% higher’ than previously estimated — RT

” The amount of Cesium-137 leaked from the Fukushima nuclear power plant could be worse than expected, a Japanese research team has concluded. They believe 50 percent more of the radioactive material could have escaped into the atmosphere and seawater.

The original estimate of 13,600 terabecquerels was made by Tokyo Electric Power Co. (TEPCO), the operator of the power station. However, a new report by Japanese researchers estimates that between 17,500 and 20,500 terabecquerels have been released, which is 50 percent higher than originally thought.

Michio Aoyama, a professor at Fukushima University’s Institute of Environmental Radioactivity who is part of the team, told Kyodo News that TEPCO is “underestimating” the amount of Cesium-137 that was released into the atmosphere and later fell into the sea.

Cesium-137 is a radioactive isotope produced by nuclear fission. However, it is problematic due to its ability to spread easily as it is highly soluble. It is also very harmful to humans and can cause cancer, while it has a half-life of around 30 years.

The team announced its findings at a conference in Vienna and it will come as another blow concerning their handling of the accident, which happened in 2011 after being triggered by a tsunami, following an earthquake in the Pacific Ocean off the Japanese coast.

Three weeks ago, the manager of the plant, Akira Ono, said attempts to plug the leaks of radioactive water had failed.

“It’s embarrassing to admit, but there are certain parts of the site where we don’t have full control,” Ono told Reuters. Last year, Japanese PM Shinzo Abe attempted to assure the world that the situation at the stricken nuclear power plant was under control.

The Fukushima plant contains radiation equivalent to 14,000 times the amount released in the atomic bomb attack on Hiroshima 68 years ago. The main task now is to try and limit the fallout from the disaster, with Aoyama saying, “the release of radioactive cesium-137 has a big impact on the ocean,” since the Fukushima nuclear complex is near the coast.

TEPCO has consistently faced contaminated water leaks at the Fukushima plant. Water has to be pumped over the facilities’ stricken reactors to keep them from overheating, but this process creates large quantities of contaminated water which has to be stored in tanks on the site.

Ono acknowledged to the media that in TEPCO’s rush to deal with the stricken facility following the earthquake-triggered tsunami in 2011, the company may have made mistakes.

“It may sound odd, but this is the bill we have to pay for what we have done in the past three years,” he said. “But we were pressed to build tanks in a rush and may have not paid enough attention to quality. We need to improve quality from here.”

TEPCO will have to improve the quality of the tanks so the plant can survive the next 30 to 40 years of the decommissioning process, Ono said. ”

source

Concerns over measurement of Fukushima fallout — The New York Times

” TOKYO — In the chaotic, fearful weeks after the Fukushima nuclear crisis began, in March 2011, researchers struggled to measure the radioactive fallout unleashed on the public. Michio Aoyama’s initial findings were more startling than most. As a senior scientist at the Japanese government’s Meteorological Research Institute, he said levels of radioactive cesium 137 in the surface water of the Pacific Ocean could be 10,000 times as high as contamination after Chernobyl, the world’s worst nuclear accident.

Two months later, as Mr. Aoyama prepared to publish his findings in a short, nonpeer-reviewed article for Nature, the director general of the institute called with an unusual demand — that Mr. Aoyama remove his own name from the paper.

“He said there were points he didn’t understand, or want to understand,” the researcher recalled. “I was later told that he did not want to say that Fukushima radioactivity was worse than Chernobyl.” The head of the institute, who has since retired, declined to comment for this article. Mr. Aoyama asked for his name to be removed, he said, and the article was not published.

The pressure he felt is not unusual — only his decision to speak about it. Off the record, university researchers in Japan say that even now, three years after the triple meltdown at the Fukushima Daiichi plant, they feel under pressure to play down the impact of the disaster. Some say they cannot get funds or university support for their work. In several cases, the professors say, they have been obstructed or told to steer clear of data that might cause public “concern.”

“Getting involved in this sort of research is dangerous politically,” said Joji Otaki, a biologist at Japan’s Ryukyu University who has written papers suggesting that radioactivity at Fukushima has triggered inherited deformities in a species of butterfly. His research is paid for through private donations, including crowdfunding, a sign, he said, that the public supports his work. “It’s an exceptional situation,” he said.

The precise health impact of the Fukushima disaster is disputed. The government has defined mandatory evacuation zones around the Daiichi plant as areas where cumulative dose levels might reach 20 millisieverts per year, the typical worldwide limit for nuclear-power-plant workers. The limit recommended by the International Commission on Radiological Protection is one millisievert per year for the public, though some scientists argue that below 100 millisieverts the threat of increased cancers is negligible.

In an effort to lower radiation and persuade about 155,000 people to return home, the government is trying to decontaminate a large area by scraping away millions of tons of radioactive dirt and storing it in temporary dumps. Experts at Japan’s National Institute of Advanced Industrial Science and Technology put the cost of this project at $50 billion — widely considered an underestimate.

The chance to study in this real-life laboratory has drawn a small number of researchers from around the world. Timothy A. Mousseau, a professor of biological sciences at the University of South Carolina who has written widely on Chernobyl, studies the impact of radiation on bird and insect life. He has published papers suggesting abnormalities and defects in some Fukushima species. But he said his three research excursions to Japan had been difficult. … ”

continue reading