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Cesium does not decay in Chernobyl as fast as predicted
Chernobyl Exclusion Zone Radioactive Longer Than Expected
SAN FRANCISCO Chernobyl, the worst nuclear accident in history, created an inadvertent laboratory to study the impacts of radiation and more than twenty years later, the site still holds surprises.
Re inhabiting the large exclusion zone around the accident site may have to wait longer than expected. Radioactive cesium isnt disappearing from the environment as quickly as predicted, according to new research presented here Monday at the meeting of the American Geophysical Union. Cesium 137′s half-life the time it takes for half of a given amount of material to decay is 30 years. In addition to that, cesium-137s total ecological half-life the time for half the cesium to disappear from the local environment through processes such as migration, weathering, and removal by organisms is also typically 30 years or less, but the amount of cesium in soil near Chernobyl isnt decreasing nearly that fast. And scientists dont know why.
It stands to reason that at some point the Ukrainian government would like to be able to use that land again, but the scientists have calculated that what they call cesiums ecological half-life the time for half the cesium to disappear from the local environment is between 180 and 320 years.
Normally youd say that every 30 years, its half as bad as it was. But its not, said Tim Jannik, nuclear scientist at Savannah River National Laboratory and a collaborator on the work. Its going to be longer before they repopulate the area.
In 1986, after the Chernobyl accident, a series of test sites was established along paths that scientists expected the fallout to take. Soil samples were taken at different depths to gauge how the radioactive isotopes of strontium, cesium and plutonium migrated in the ground. Theyve been taking these measurements for more than 20 years, providing a unique experiment in the long-term environmental repercussions of a near worst-case nuclear accident.
In some ways, Chernobyl is easier to understand than DOE sites like Hanford, which have been contaminated by long-term processes. With Chernobyl, said Boris Faybishenko, a nuclear remediation expert at Lawrence Berkeley National Laboratory, we have a definite date at which the contamination began and a series of measurements carried out from that time to today.
I have been involved in Chernobyl studies for many years and this particular study could be of great importance to many [Department of Energy] researchers, said Faybishenko.
The results of this study came as a surprise. Scientists expected the ecological half-lives of radioactive isotopes to be shorter than their physical half-life as natural dispersion helped reduce the amount of material in any given soil sample. For strontium, that idea has held up. But for cesium the the opposite appears to be true.
The physical properties of cesium havent changed, so scientists think there must be an environmental explanation. It could be that new cesium is blowing over the soil sites from closer to the Chernobyl site. Or perhaps cesium is migrating up through the soil from deeper in the ground. Jannik hopes more research will uncover the truth.
There are a lot of unknowns that are probably causing this phenomenon, he said.
Beyond the societal impacts of the study, the work also emphasizes the uncertainties associated with radioactive contamination. Thankfully, Chernobyl-scale accidents have been rare, but that also means there is a paucity of places to study how radioactive contamination really behaves in the wild.
The data from Chernobyl can be used for validating models, said Faybishenko. This is the most value that we can gain from it.
Ishihara Tokyo governor plans to build a nuclear plant along Tokyo bay
Having received the petition of 320,000 people for referendum of nuclear power, Ishihara Tokyo governor mentioned the plan to build a nuclear plant along the coast of Tokyo bay.
He believes Fukushima plants were damaged by Tsunami, suggests to build one on the mountain in Chiba.
He stated Mt. Nokogiri yama in Chiba is 329m of height, 1km from Tokyo bay so it can take water from Tokyo bay for its coolant system.
Ishihara mentioned this plan at Metropolitan Assembly budget Committee on 3/14/2012 at first but local residents opposed the plan. Ishihara commented, it was merely an idea for civilization, but he wont apologize.
Fukushima elementary schools held sports festival
All of the 52 elementary schools in Fukushima held sports festival on 5/12/2012 on the assumption that radiation was removed by decontamination.
They cancelled it or held it in gymnasium last year.
They shortened the time and made students wear masks when they touch the ground.
【原発】2年ぶり屋外で運動会 福島 小学校（12/05/12） - YouTube
V
Chernobyl Exclusion Zone Radioactive Longer Than Expected
SAN FRANCISCO Chernobyl, the worst nuclear accident in history, created an inadvertent laboratory to study the impacts of radiation and more than twenty years later, the site still holds surprises.
Re inhabiting the large exclusion zone around the accident site may have to wait longer than expected. Radioactive cesium isnt disappearing from the environment as quickly as predicted, according to new research presented here Monday at the meeting of the American Geophysical Union. Cesium 137′s half-life the time it takes for half of a given amount of material to decay is 30 years. In addition to that, cesium-137s total ecological half-life the time for half the cesium to disappear from the local environment through processes such as migration, weathering, and removal by organisms is also typically 30 years or less, but the amount of cesium in soil near Chernobyl isnt decreasing nearly that fast. And scientists dont know why.
It stands to reason that at some point the Ukrainian government would like to be able to use that land again, but the scientists have calculated that what they call cesiums ecological half-life the time for half the cesium to disappear from the local environment is between 180 and 320 years.
Normally youd say that every 30 years, its half as bad as it was. But its not, said Tim Jannik, nuclear scientist at Savannah River National Laboratory and a collaborator on the work. Its going to be longer before they repopulate the area.
In 1986, after the Chernobyl accident, a series of test sites was established along paths that scientists expected the fallout to take. Soil samples were taken at different depths to gauge how the radioactive isotopes of strontium, cesium and plutonium migrated in the ground. Theyve been taking these measurements for more than 20 years, providing a unique experiment in the long-term environmental repercussions of a near worst-case nuclear accident.
In some ways, Chernobyl is easier to understand than DOE sites like Hanford, which have been contaminated by long-term processes. With Chernobyl, said Boris Faybishenko, a nuclear remediation expert at Lawrence Berkeley National Laboratory, we have a definite date at which the contamination began and a series of measurements carried out from that time to today.
I have been involved in Chernobyl studies for many years and this particular study could be of great importance to many [Department of Energy] researchers, said Faybishenko.
The results of this study came as a surprise. Scientists expected the ecological half-lives of radioactive isotopes to be shorter than their physical half-life as natural dispersion helped reduce the amount of material in any given soil sample. For strontium, that idea has held up. But for cesium the the opposite appears to be true.
The physical properties of cesium havent changed, so scientists think there must be an environmental explanation. It could be that new cesium is blowing over the soil sites from closer to the Chernobyl site. Or perhaps cesium is migrating up through the soil from deeper in the ground. Jannik hopes more research will uncover the truth.
There are a lot of unknowns that are probably causing this phenomenon, he said.
Beyond the societal impacts of the study, the work also emphasizes the uncertainties associated with radioactive contamination. Thankfully, Chernobyl-scale accidents have been rare, but that also means there is a paucity of places to study how radioactive contamination really behaves in the wild.
The data from Chernobyl can be used for validating models, said Faybishenko. This is the most value that we can gain from it.
Ishihara Tokyo governor plans to build a nuclear plant along Tokyo bay
Having received the petition of 320,000 people for referendum of nuclear power, Ishihara Tokyo governor mentioned the plan to build a nuclear plant along the coast of Tokyo bay.
He believes Fukushima plants were damaged by Tsunami, suggests to build one on the mountain in Chiba.
He stated Mt. Nokogiri yama in Chiba is 329m of height, 1km from Tokyo bay so it can take water from Tokyo bay for its coolant system.
Ishihara mentioned this plan at Metropolitan Assembly budget Committee on 3/14/2012 at first but local residents opposed the plan. Ishihara commented, it was merely an idea for civilization, but he wont apologize.
Fukushima elementary schools held sports festival
All of the 52 elementary schools in Fukushima held sports festival on 5/12/2012 on the assumption that radiation was removed by decontamination.
They cancelled it or held it in gymnasium last year.
They shortened the time and made students wear masks when they touch the ground.
【原発】2年ぶり屋外で運動会 福島 小学校（12/05/12） - YouTube
V
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