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March 11th 2016
On March 11, 2011, a giant
tsunami from the Pacific Ocean swept over the 10-meter sea wall
surrounding six reactors at the Fukushima power plant on Japan’s east
coast. The crashing water caused reactor cores to overheat
and melt, and subsequent hydrogen explosions damaged three reactor
buildings. Radiation spewed in every direction. The country shut down
all of its more than 40 reactors, and investigations began into radiation exposure to tens of thousands of nearby residents, as well as to wildlife on land and sea.
But major questions still loom today, in part because the damaged
reactors are too dangerous to enter, and in part because the plant's
operator, the Tokyo Electric Power Company (Tepco), is reluctant to
In the midst of this maelstrom, Japan in February started up a third
reactor among those that had been shut down. But even as the government
seeks to leave the disaster behind, Fukushima remains a wound that will
not heal—for former residents, the local landscape and for the Japanese
psyche. Two-thirds of the populace dreads another accident enough to
oppose the restarts. More than 1,100 square kilometers of villages,
mountains and forests remain uninhabitable, and future generations will
still be cleaning up the plant site, according to Japan's Ministry of
Economy, Trade and Industry (METI). Echoing citizens' groups, some
scientists are complaining that important questions about the disaster's
impact are not being addressed. Authorities, they suspect, are subtly
discouraging certain kinds of scientific research, possibly because they
fear findings that could further alarm the public. In some ways they
want this to go away and say things are back to normal, observes marine
radiochemist Ken Buesseler of Woods Hole Oceanographic Institute in
Woods Hole, Mass.
Exacerbating widespread suspicions of a cover-up, this February Tepco
admitted it had waited for two months after the accident before
announcing the meltdowns—which possibly delayed evacuations and
endangered lives. The uranium fuel in three of the six reactors
eventually melted, and explosions blew holes in the roofs of three
reactor buildings, releasing radioactive iodine, cesium and other
fission products over land and sea. Emergency managers on site,
desperately trying to cool the molten cores, poured water into the
damaged reactor buildings using fire-hoses. As a result, highly
contaminated water flowed directly into the Pacific Ocean.
Since then, Tepco has substantially cleaned up the site. It has
capped shredded roofs, removed spent fuel from a damaged reactor and
constructed ice walls to stanch the flow of groundwater that was washing
contaminants from the site into the ocean. Because the molten fuel
still generates heat by radioactive decay, however, Tepco has to keep
pumping water through the reactor buildings and collecting as much as
possible—some 400 cubic meters a day, stored in on-site tanks. Around
8,000 workers are now assisting in the cleanup.
naturalflow/Flickr, CC BY-SA 2.0
Not all is going well, however. Engineers still have to locate the
molten fuel, which seems to have melted through steel vessels. It
remains so radioactive that no humans can enter the reactor buildings.
Tepco has "no idea where and how much fuel debris is in the reactor
now," says nuclear engineer Tadahiro Katsuta of Meiji University. Last
April, Tepco sent a robot into one of the buildings
to photograph the damage, with mixed results, and it also intends to
use robots to find and remove the globs of molten uranium, steel and
other substances by 2021. According to METI, fully cleaning the site
will require half a century, when most of the dangerous radionuclides
will have decayed. Where the lethal debris will end up is unclear,
however, because Japan has no permanent repository for nuclear waste.
The 1,000 or so tanks of contaminated water, which leak from time to time, pose another headache. Tepco is removing the most abundant contaminant, cesium,
from the cooling water before it is sent to the storage tanks, but the
water retains high concentrations of radioactive strontium and tritium.
This February, the company reported a spike in strontium levels at the
plant site—likely indicating a tank leak. So the company is
painstakingly cleaning the stored water of all radionuclides except
tritium, which is difficult to separate out. Because tritium
concentrations remain many times higher than the drinking water level
prescribed by the World Health Organization, however, fishery
cooperatives are not allowing its release into the ocean. (Tepco did not
respond to Scientific American's questions about the tank contents, or
Solid waste is piling up as well. Cleaning streets, houses and
playgrounds within the evacuated zone, which stretches some 50
kilometers northwest of the plant site, has generated millions of bags
of contaminated topsoil and debris, which also await a final resting
place. Almost 800 bags got carried off by typhoon Etau last year,
however, and were deposited miles away, says Hajime Matsukubo of the
Citizen's Nuclear Information Center in Tokyo. Hundreds were never
Meanwhile, after five years, some 100,000 people are still waiting to
return to their homes. Last year the Japanese government announced that
it will eventually lift evacuation orders for regions where a person
would receive an annual radiation dose of 20 millisieverts or less. That
figure, several times higher than what the International Commission on
Radiological Protection recommends for safety, poses an "unacceptable"
risk, Matsukubo says. (According to a report from the U.S. National
Academy of Sciences, a dose of 20 millisieverts increases the chances of
mortality from cancer by roughly one in 1,000, and residents would be
receiving comparable doses year after year.) No matter: a year after
this zone is opened up, Tepco will stop providing compensation to its
32,000 former residents. Exile may be permanent, however, for tens of
thousands of people from the most contaminated areas.
Cesium (Cs) and Strontium (Sr) levels in seawater just off
the Fukushima plant site have fallen steeply since the accident, but two
years later remained well above pre-accident levels.
This figure is reproduced from slide #2 in Michio Aoyama's presentation at IAEA Scientific Forum 17-18 September 2013 Vienna, Austria ( http://www-pub.iaea.org/MTCD/Meetings/PDFplus/2013/cn207/Presentations/1028-Aoyama.pdf) with permission of Aoyama. Accidents, ailments and trauma caused by the evacuation has led to 3,200 deaths, including many suicides, according to the World Nuclear Industry Status Report, 2015. The number of cancer cases is hotly disputed. A 2013 study published in Energy and Environmental Science estimated roughly 1,000 future cancer deaths from radioactive cesium, too few to be distinguished from those caused by other factors. Last year, however, an ultrasound screening program of around 300,000 children who had been living in the affected area revealed a startling 110 thyroid cancers—a 30-fold increase from the norm, allegedly caused by radioactive iodine. Radiation epidemiologist Yoshisada Shibata of Nagasaki University dismisses as "nonsense" the claim that the disaster is responsible for those cases, however. Unlike in Chernobyl, he explains, no Fukushima children who were infants at the time of the disaster have tumors. Moreover, many of the growths are surprisingly big. "It's too fast," he says. "If these cancers started after the accident, it's not possible that they should grow so large." The highly sensitive screening method employed, he and others contend, has detected growths that would never have become problematic enough to be diagnosed by a doctor—so its results cannot be gauged against those from other surveys, they say. Other studies indicate that the disaster has adversely affected many other creatures—in particular those living in the forests, which have not been cleaned. In a count of 57 species of birds in 400 locations of varying radioactivity, ecologists Anders Møller of the National Center for Scientific Research in Orsay, France, and Timothy Mousseau of the University of South Carolina documented sharp reductions in abundance and diversity in the areas of higher contamination. The team's ongoing studies in Chernobyl, which has a similar biotope, may indicate why: many birds have "cataracts in the eyes, smaller brain size, tumors, reduced fertility, especially in the males," says Mousseau—all of which decrease their ability to survive. In another study, conducted in less contaminated areas, a Japanese team found physiological and genetic damage in an ubiquitous species of butterfly, the pale grass blue. Other researchers have documented defects in the growth of almost all fir trees in highly contaminated areas, abnormalities in aphids near the power plant and the activation of a DNA-repair mechanism in rice plants in response to radiation. Despite such scattered findings, however, no comprehensive evaluation exists of how the terrestrial ecosystem is faring under the radioactive onslaught. Remarkably, research on Fukushima's impact on the marine ecosystem is even more scarce—even though the disaster represented the single largest pulse of radioactivity ever injected into an ocean. In 2011, Nicholas Fisher of the University of Stonybrook found widespread cesium contamination of zooplankton and small fish up to 600 kilometers off the Japanese coast, and in 2011 another study documented the absence of rock shell snails in a 30-kilometer stretch of coastline near Fukushima. But little else is known about the accident's impact on marine organisms The damaged Fukushima Daiichi Nuclear Power Station as seen during a sea-water sampling boat journey, 7 November 2013. IAEA marine monitoring experts were sent to Japan to observe sea water sampling and data analysis.
IAEA Imagebank/Flickr, CC BY-SA 2.0 Although the cesium concentration has now fallen below regulatory limits because of dilution in the Pacific, its level in the ocean many kilometers off Fukushima remains well above pre-accident levels. One reason is that rain and rivers keep washing the radionuclide off the land and into the sea. In addition, roughly a hundredth of the blast of radiocesium released in 2011 seems to have been absorbed into clays on the seafloor. "It's going to stay put near Japan," Buesseler says. As a consequence, levels of cesium also remain elevated in fish such as greenlings, which feed off the sediments close to the Fukushima plant site. Another concern is radioactive strontium. Scientists say levels in seawater near the plant are not declining, possibly because of recurrent leaks from the on-site tanks. "You could actually see in the ocean when one of these tanks would leak—you’d get a big spike in Strontium-90," Buesseler notes. Whereas cesium behaves in organisms rather like potassium, being absorbed and excreted fairly quickly, strontium is chemically similar to calcium and accumulates in bones. Although consumers of Fukushima's fish may be safe, because they tend not to eat fish-bones, the radionuclide could become a long-term concern for a few of the fish themselves. Mathew P. Johansen of the Australian Nuclear Science and Technology Organization and others estimate that, for the first three years at least, certain species such as greenlings living very close to the plant received such high doses from cesium and strontium that reduced reproduction and subtle genetic changes were possible. Johansen calls for investigations into the ecological web built upon the now contaminated sediments off Fukushima. Indeed, unanswered questions abound. "You want to know why some fish have higher contamination than others, how quickly they will recover, what's coming down the rivers, how much is on the seafloor, how quickly that is buried—those are the type of oceanography and radioecology questions that are really not being well addressed," Buesseler says. One reason is the scarcity of funds for such research, argues Mousseau. The Japanese government seems to be cutting off funds for monitoring radionuclides in water alongside Fukushima, Buesseler says. Shibata finds such concerns "biased," pointing out that several ministries offer funds for environmental research. But another Japanese scientist, who asked not to be named, claimed that whereas grants are readily available for researchers whose projects are unlikely to discover significant impacts from the disaster, they are exceedingly scarce for others. Other muddiness remains. Several Japanese researchers who aided Mousseau's team asked not to be credited in its published papers, fearing adverse impacts on their careers. Buesseler reports a similar experience. "There's this kind of self-censorship going on," Mousseau says. With more than 400 nuclear power plants operating around the world, many of them on coastlines and in countries with far weaker safety standards than Japan's, another such calamity is not inconceivable. Knowing more about its impacts could help save lives and livelihoods. Unfortunately, Buesseler notes, "We're missing opportunities to learn from this accident."
The top picture is of radiological contamination on an amusement park which was hastily abandoned due to the contamination caused by the Chernobyl nuclear accident, huge areas of the country was laid to waste with no possibility of human habitation for many hundreds of years, there are of course still wild animals living in the vicinity and these are monitored by the authorities to determine the effects of overexposure to radiation
Radiological Contamination can occur in the many different ways, the sources of radiation are spread throughout our world, some are natural and are spread throughout the earth’s crust, the ones we need to concern ourselves with are man-made, the most common are X Ray machines that are spread liberally in nearly every country in the world in hospitals and clinics, these are very well controlled and the contamination they cause is minor and normally caused to individuals having diagnostic examinations or treatment.
There have been cases of accidental contamination where an x-ray machine has been taken out of service, scrapped and sent for recycling without first removing the radiation source, the recycled steel was then used to make very many everyday objects, a widespread investigation revealed radiation coming from such things as restaurant furniture and white goods, refrigerators and washing machines, fortunately in modern times the authorities are much more careful.
The more serious radiation leaks are from nuclear power stations, accidents are rare but they are very serious. The accident at Chernobyl is very well documented, caused many deaths and laid waste to thousands of square miles of contaminated land, including cities as pictured above and where ever there was fallout the land, the animals and the produce was unusable.
The molten mass of the meltdown material was stopped in the basement of the reactor building by the simple fact that there was plenty of sand lying about, this caused the fissile material to turn into glass, it would be a good idea if all reactor buildings had this provision built in.
The other seriously accident was at a power station in Japan, this was caused by an earthquake and resultant tsunami, this one also is well known and well documented.
There was another incident in America at Three Mile island where there was a partial meltdown of the reactor core.
Fortunately with modern communication systems these dangerous situations can be monitored easily and warnings issued by local government, civil defense, police, local radio and television.
Abandoned city in Russia
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