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Japan struggles to store nuclear plant water
DOHA - Japan's crippled nuclear power plant in Fukushima is struggling to find space to store tens of thousands of tonnes of highly contaminated water used to cool the broken reactors, the manager of the water treatment team has said.
About 200,000 tonnes of radioactive water, enough to fill more than 50 Olympic-sized swimming pools, are being stored in hundreds of gigantic tanks built around the Fukushima Daiichi plant.
Operator Tokyo Electric Power Company (TEPCO) has already chopped down trees to make room for more tanks and predicts the volume of water will be more than tripled within three years.
"It's a time-pressing issue because the storage of contaminated water has its limits, there is only limited storage space," the water-treatment manager, Yuichi Okamura, told the AP news agency in an interview this week.
Dumping massive amounts of water into the melting reactors was the only way to avoid an even bigger catastrophe after the meltdown at TEPCOs Fukushima Daiichi nuclear power reactor, caused by the March 11, 2011, tsunami.
Okamura remembers frantically trying to find a way to get water to spent fuel pools located on the highest floor of the 50m high reactor buildings. Without water, the spent fuel likely would have overheated and melted, sending radioactive smoke for miles and affecting possibly millions of people.
The measures to keep the plant under control created another huge headache for the utility: what to do with all the radioactive water that leaked out of the damaged reactors and collected in the basements of reactor buildings and nearby facilities.
"At that time, we never expected high-level contaminated water to turn up in the turbine building," Okamura said.
He was tasked with setting up a treatment system that would make the water clean enough for reuse as a coolant, and was also aimed at reducing health risks for workers and at curbing environmental damage.
At first, the utility shunted the tainted water into existing storage tanks near the reactors. Meanwhile, Okamura's 55-member team scrambled to get a treatment unit up and running within three months of the accident, a project that would normally take about two years, he said. Using that equipment, TEPCO was able to circulate reprocessed water back into the reactor cores.
Even though the reactors now are being cooled exclusively with recycled water, the volume of contaminated water is still increasing, mostly because groundwater is seeping through cracks into the reactor and turbine basements.
Next month, Okamura's group plans to flip the switch on new purifying equipment using Toshiba Corp technology. "By purifying the water using the ALPS system, theoretically, all radioactive products can be purified to below detection levels," he said.
In the meantime its tanks are filling up, mostly because leaks in reactor facilities are allowing groundwater to pour in.
Masashi Goto, a nuclear engineer and university lecturer, said the contaminated water build-up posed a major long-term threat to health and the environment. He said the radioactive water in the basements may already be getting into the underground water system, where it could reach far beyond the plant via underground water channels, possibly reaching the ocean or public water supplies.
"There are pools of some 10,000 or 20,000 tonnes of contaminated water in each plant, and there are many of these, and to bring all of these to one place would mean you would have to treat hundreds of thousands of tonnes of contaminated water, which is mind-blowing in itself," Goto said. "It's an outrageous amount, truly outrageous.".
The plant will have to deal with contaminated water until all the melted fuel and other debris is removed from the reactor, a process that will easily take more than a decade.
(Inter Press Service)
Fish Off Japan’s Coast Said to Contain Elevated Levels of Cesium
By HIROKO TABUCHI
TOKYO — Elevated levels of cesium still detected in fish off the Fukushima coast of Japan suggest that radioactive particles from last year’s nuclear disaster have accumulated on the seafloor and could contaminate sea life for decades, according to new research.
The findings published in Friday’s issue of the journal Science highlight the challenges facing Japan as it seeks to protect its food supply and rebuild the local fisheries industry.
More than 18 months after the nuclear disaster, Japan bans the sale of 36 species of fish caught off Fukushima, rendering the bulk of its fishing boats idle and denying the region one of its mainstay industries.
Some local fishermen are trying to return to work. Since July, a handful of them have resumed small-scale commercial fishing for species, like octopus, that have cleared government radiation tests. Radiation readings in waters off Fukushima and beyond have returned to near-normal levels.
But about 40 percent of fish caught off Fukushima and tested by the government still have too much cesium to be safe to eat under regulatory limits set by the Japanese government last year, said the article’s author, Ken O. Buesseler, a leading marine chemistry expert at the Woods Hole Oceanographic Institution, who analyzed test results from the 12 months following the March 2011 disaster.
Because cesium tends not to stay very long in the tissues of saltwater fish — and because high radiation levels have been detected most often in bottom-feeding fish — it is likely that fish are being newly contaminated by cesium on the seabed, Mr. Buesseler wrote in the Science article.
“The fact that many fish are just as contaminated today with cesium 134 and cesium 137 as they were more than one year ago implies that cesium is still being released into the food chain,” Mr. Buesseler wrote. This kind of cesium has a half-life of 30 years, meaning that it falls off by half in radioactive intensity every 30 years. Given that, he said, “sediments would remain contaminated for decades to come.”
Officials at Japan’s Fisheries Agency, which conducted the tests, said Mr. Buesseler’s analysis made sense.
“In the early days of the disaster, as the fallout hit the ocean, we saw high levels of radiation from fish near the surface,” said Koichi Tahara, assistant director of the agency’s resources and research division. “But now it would be reasonable to assume that radioactive substances are settling on the seafloor.”
But that was less of a concern than Mr. Buesseler’s research might suggest, Mr. Tahara said, because the cesium was expected to eventually settle down into the seabed.
Mr. Tahara also stressed that the government would continue its vigorous testing and that fishing bans would remain in place until radiation readings returned to safe levels.
Naohiro Yoshida, an environmental chemistry expert at the Tokyo Institute of Technology, said that while he agreed with much of Mr. Buesseler’s analysis, it was too early to reach a conclusion on how extensive radioactive contamination of Japan’s oceans would be, and how long it would have an impact on marine life in the area.
Further research was needed on ocean currents, sediments and how different species of fish are affected by radioactive contamination, he said.
As much as four-fifths of the radioactive substances released from the Fukushima Daiichi nuclear power plant are thought to have entered the sea, either blown offshore or released directly into the ocean from water used to cool the site’s reactors in the wake of the accident.
Sea currents quickly dispersed that radioactivity, and seawater readings off the Fukushima shore returned to near-normal levels. But fish caught in the area continue to show elevated readings for radioactive cesium, which is associated with an increased risk of cancer in humans.
Just two months ago, two greenling caught close to the Fukushima shore were found to contain more than 25,000 becquerels a kilogram of cesium, the highest cesium levels found in fish since the disaster and 250 times the government’s safety limit.
The operator of the Fukushima plant, the Tokyo Electric Power Company, said that the site no longer released contaminated water into the ocean, and that radiation levels in waters around the plant had stabilized.
But Yoshikazu Nagai, a spokesman for the company, said he could not rule out undetected leaks into the ocean from its reactors, the basements of which remain flooded with cooling water.
To reduce the chance of water from seeping out of the plant, Tokyo Electric is building a 2,400-foot-long wall between the site’s reactors and the ocean. But Mr. Nagai said the steel-and-concrete wall, which will reach 100 feet underground, would take until mid-2014 to build.
http://www.nytimes.com/2012/10/26/wo...gewanted=print
DOHA - Japan's crippled nuclear power plant in Fukushima is struggling to find space to store tens of thousands of tonnes of highly contaminated water used to cool the broken reactors, the manager of the water treatment team has said.
About 200,000 tonnes of radioactive water, enough to fill more than 50 Olympic-sized swimming pools, are being stored in hundreds of gigantic tanks built around the Fukushima Daiichi plant.
Operator Tokyo Electric Power Company (TEPCO) has already chopped down trees to make room for more tanks and predicts the volume of water will be more than tripled within three years.
"It's a time-pressing issue because the storage of contaminated water has its limits, there is only limited storage space," the water-treatment manager, Yuichi Okamura, told the AP news agency in an interview this week.
Dumping massive amounts of water into the melting reactors was the only way to avoid an even bigger catastrophe after the meltdown at TEPCOs Fukushima Daiichi nuclear power reactor, caused by the March 11, 2011, tsunami.
Okamura remembers frantically trying to find a way to get water to spent fuel pools located on the highest floor of the 50m high reactor buildings. Without water, the spent fuel likely would have overheated and melted, sending radioactive smoke for miles and affecting possibly millions of people.
The measures to keep the plant under control created another huge headache for the utility: what to do with all the radioactive water that leaked out of the damaged reactors and collected in the basements of reactor buildings and nearby facilities.
"At that time, we never expected high-level contaminated water to turn up in the turbine building," Okamura said.
He was tasked with setting up a treatment system that would make the water clean enough for reuse as a coolant, and was also aimed at reducing health risks for workers and at curbing environmental damage.
At first, the utility shunted the tainted water into existing storage tanks near the reactors. Meanwhile, Okamura's 55-member team scrambled to get a treatment unit up and running within three months of the accident, a project that would normally take about two years, he said. Using that equipment, TEPCO was able to circulate reprocessed water back into the reactor cores.
Even though the reactors now are being cooled exclusively with recycled water, the volume of contaminated water is still increasing, mostly because groundwater is seeping through cracks into the reactor and turbine basements.
Next month, Okamura's group plans to flip the switch on new purifying equipment using Toshiba Corp technology. "By purifying the water using the ALPS system, theoretically, all radioactive products can be purified to below detection levels," he said.
In the meantime its tanks are filling up, mostly because leaks in reactor facilities are allowing groundwater to pour in.
Masashi Goto, a nuclear engineer and university lecturer, said the contaminated water build-up posed a major long-term threat to health and the environment. He said the radioactive water in the basements may already be getting into the underground water system, where it could reach far beyond the plant via underground water channels, possibly reaching the ocean or public water supplies.
"There are pools of some 10,000 or 20,000 tonnes of contaminated water in each plant, and there are many of these, and to bring all of these to one place would mean you would have to treat hundreds of thousands of tonnes of contaminated water, which is mind-blowing in itself," Goto said. "It's an outrageous amount, truly outrageous.".
The plant will have to deal with contaminated water until all the melted fuel and other debris is removed from the reactor, a process that will easily take more than a decade.
(Inter Press Service)
Fish Off Japan’s Coast Said to Contain Elevated Levels of Cesium
By HIROKO TABUCHI
TOKYO — Elevated levels of cesium still detected in fish off the Fukushima coast of Japan suggest that radioactive particles from last year’s nuclear disaster have accumulated on the seafloor and could contaminate sea life for decades, according to new research.
The findings published in Friday’s issue of the journal Science highlight the challenges facing Japan as it seeks to protect its food supply and rebuild the local fisheries industry.
More than 18 months after the nuclear disaster, Japan bans the sale of 36 species of fish caught off Fukushima, rendering the bulk of its fishing boats idle and denying the region one of its mainstay industries.
Some local fishermen are trying to return to work. Since July, a handful of them have resumed small-scale commercial fishing for species, like octopus, that have cleared government radiation tests. Radiation readings in waters off Fukushima and beyond have returned to near-normal levels.
But about 40 percent of fish caught off Fukushima and tested by the government still have too much cesium to be safe to eat under regulatory limits set by the Japanese government last year, said the article’s author, Ken O. Buesseler, a leading marine chemistry expert at the Woods Hole Oceanographic Institution, who analyzed test results from the 12 months following the March 2011 disaster.
Because cesium tends not to stay very long in the tissues of saltwater fish — and because high radiation levels have been detected most often in bottom-feeding fish — it is likely that fish are being newly contaminated by cesium on the seabed, Mr. Buesseler wrote in the Science article.
“The fact that many fish are just as contaminated today with cesium 134 and cesium 137 as they were more than one year ago implies that cesium is still being released into the food chain,” Mr. Buesseler wrote. This kind of cesium has a half-life of 30 years, meaning that it falls off by half in radioactive intensity every 30 years. Given that, he said, “sediments would remain contaminated for decades to come.”
Officials at Japan’s Fisheries Agency, which conducted the tests, said Mr. Buesseler’s analysis made sense.
“In the early days of the disaster, as the fallout hit the ocean, we saw high levels of radiation from fish near the surface,” said Koichi Tahara, assistant director of the agency’s resources and research division. “But now it would be reasonable to assume that radioactive substances are settling on the seafloor.”
But that was less of a concern than Mr. Buesseler’s research might suggest, Mr. Tahara said, because the cesium was expected to eventually settle down into the seabed.
Mr. Tahara also stressed that the government would continue its vigorous testing and that fishing bans would remain in place until radiation readings returned to safe levels.
Naohiro Yoshida, an environmental chemistry expert at the Tokyo Institute of Technology, said that while he agreed with much of Mr. Buesseler’s analysis, it was too early to reach a conclusion on how extensive radioactive contamination of Japan’s oceans would be, and how long it would have an impact on marine life in the area.
Further research was needed on ocean currents, sediments and how different species of fish are affected by radioactive contamination, he said.
As much as four-fifths of the radioactive substances released from the Fukushima Daiichi nuclear power plant are thought to have entered the sea, either blown offshore or released directly into the ocean from water used to cool the site’s reactors in the wake of the accident.
Sea currents quickly dispersed that radioactivity, and seawater readings off the Fukushima shore returned to near-normal levels. But fish caught in the area continue to show elevated readings for radioactive cesium, which is associated with an increased risk of cancer in humans.
Just two months ago, two greenling caught close to the Fukushima shore were found to contain more than 25,000 becquerels a kilogram of cesium, the highest cesium levels found in fish since the disaster and 250 times the government’s safety limit.
The operator of the Fukushima plant, the Tokyo Electric Power Company, said that the site no longer released contaminated water into the ocean, and that radiation levels in waters around the plant had stabilized.
But Yoshikazu Nagai, a spokesman for the company, said he could not rule out undetected leaks into the ocean from its reactors, the basements of which remain flooded with cooling water.
To reduce the chance of water from seeping out of the plant, Tokyo Electric is building a 2,400-foot-long wall between the site’s reactors and the ocean. But Mr. Nagai said the steel-and-concrete wall, which will reach 100 feet underground, would take until mid-2014 to build.
http://www.nytimes.com/2012/10/26/wo...gewanted=print
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