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5 years on, and Fukushima nuclear station still very dangerous

Fukushima Units 3 and 4, April 2011highly-recommendedCrippled Fukushima Reactors Are Still a Danger, 5 Years after the Accident Japan’s citizens, and scientists worldwide, do not have answers to basic health and environment questions, Scientific American  By Madhusree Mukerjee on March 8, 2016 “…….. 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 share information.

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.

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 anything else.)

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 found……….

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.” http://www.scientificamerican.com/article/crippled-fukushima-reactors-are-still-a-danger-5-years-after-the-accident1/

March 11, 2016 - Posted by | Fukushima 2016, Japan

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