Ra­di­a­tion fixes in Fukushima

The Financial Daily - - MONEY & FOREX -

eo­ple evac­u­ated from a dan­ger zone around Ja­pan's dam­aged Fukushima nu­clear plant may need to stay away for many months, but ex­perts say there are ways to make their re­turn swifter and eas­ier. Ra­di­a­tion lev­els in the area now are higher than nor­mal and could in­crease risks to long-term health, but so-called re­me­di­a­tion meth­ods, such as deep­plough­ing the soil, re­mov­ing top­soil al­to­gether and choos­ing crops and ways of farm­ing that don't pick up much ra­dioac­tiv­ity, can cut the risk of harm. Tens of thou­sands of peo­ple, in­clud­ing farm­ers and their fam­i­lies, have been evac­u­ated from a 20-km (12-mile) ex­clu­sion zone around the stricken Fukushima plant, and an­other 130,000 who live in a 10 km (6-mile) band be­yond the ex­clu­sion zone have been ad­vised ei­ther to leave or stay in­doors. As­sum­ing no dras­tic wors­en­ing of leaks from the tsunami- and quakedam­aged plant, there will be no longterm ex­clu­sion zone like that around Ch­er­nobyl in Ukraine, the site of the world's worst nu­clear disas­ter in 1986. "The worst-case sce­nario in terms of peo­ple re-oc­cu­py­ing the area is that peo­ple might be able to go back within months," said Steve Jones, an in­de­pen­dent nu­clear and en­vi­ron­men­tal con­sul­tant.

P"There's likely to be an ex­tended ban on food pro­duc­tion within the af­fected sec­tor -- of about 20 to 30 km out -that might per­sist for some time. But there is then also the op­tion of ap­ply­ing all sorts of re­me­dial mea­sures." Ex­perts say the key to the fu­ture of the cur­rent ex­clu­sion zone will be lev­els of ra­dioac­tive cae­sium 137, which has a half-life of 30 years. That means that its ra­dioac­tiv­ity drops by 50 per­cent ev­ery three decades. PRUS­SIAN BLUE Both cae­sium 137 and an­other ra­dionu­clide, io­dine 131, have been de­tected in crops, in the soil and in milk pro­duced in the area close to the plant. Yet ex­perts say there is no rea­son this should make the area a no-go zone for­ever. "The io­dine prob­lem will be over in a cou­ple of months," said Astrid Li­land of the Nor­we­gian Ra­di­a­tion Pro­tec­tion Au­thor­ity, ex­plain­ing that since io­dine 131 has a half-life of eight days, it will quickly dis­si­pate. That means that milk con­tam­i­nated with io­dine 131, for in­stance, can be safely made into long-life cheese. Con­sumers, how­ever, may be re­luc­tant to buy it. For cae­sium, which lingers far longer and may present a big­ger prob­lem -es­pe­cially for farm­ers of graz­ing an­i­mals -- both Li­land and Nick Beres­ford, a ra­dioe­col­o­gist at the Lan­caster En­vi­ron­ment Cen­tre in Eng­land, say the use of a chem­i­cal com­pound called Prus­sian blue is prob­a­bly the best op­tion. Prus­sian Blue binds to cae­sium to pre­vent it from be­ing taken up dur­ing di­ges­tion by cows, goats, sheep and other an­i­mals and was widely used in the ar­eas around Ch­er­nobyl. "It is still used in Nor­way to counter the ef­fects of Ch­er­nobyl, largely for sheep and goats," said Li­land. Other lessons learned from Ch­er­nobyl in­clude deep-plough­ing the soil to drive the ra­di­a­tion fur­ther down into the ground, and us­ing potas­sium fer­tiliser, ex­perts said. Potas­sium is vi­tal for liv­ing cells and ab­sorbed by plants in a sim­i­lar way to cae­sium. Since plants pre­fer to ab­sorb potas­sium, over­load­ing the soil with potas­sium can limit the up­take of cae­sium. "The ac­tiv­ity at the mo­ment will be pre­dom­i­nantly in the top few cen­time­tres of the soil pro­file, so if you're will­ing to spend an un­lim­ited amount of money you could sim­ply re­move all that, take it some­where else and bury it," added Jones. LIKE CH­ER­NOBYL AF­TER

25 YEARS Jim Smith, a spe­cial­ist in en­vi­ron­men­tal physics at Bri­tain's Portsmouth Univer­sity who has spent years study­ing the ra­di­a­tion ef­fects from Ch­er­nobyl, said it was im­por­tant not to over­play the po­ten­tial health and en­vi­ron­men­tal im­pacts from the lev­els of ra­di­a­tion seen around the Ja­panese plant. Work­ing from data from sur­veys con­ducted by teams from the United States en­ergy depart­ment and the In­ter­na­tional Atomic En­ergy Agency (IAEA), Smith said there were so far no ar­eas in which ra­di­a­tion lev­els had ex­ceeded 300 mi­crosiev­erts per hour. "Now -- 25 years on -- at Ch­er­nobyl, I've worked in ar­eas where we can still have read­ings of up to 300 mi­crosiev­erts per hour," he said. "So whilst this is clearly a sig­nif­i­cant con­tam­i­na­tion of the ter­res­trial en­vi­ron­ment, I was quite re­lieved to see these lev­els (in Ja­pan)." For or­di­nary peo­ple faced with the dilemma of whether to re­turn to their homes in the months ahead if the ex­clu­sion zone is lifted, Smith said key would be to avoid un­nec­es­sary stress. "We're in the range of dose rates where we should say... it's not go­ing to kill you im­me­di­ately, but you'd have an in­creased risk -- just as many peo­ple do from nat­u­ral ra­dioac­tiv­ity around the world -- and it's your choice," he said. "To me this is still a big­ger so­cial, eco­nomic and psy­cho­log­i­cal prob­lem than it is a ra­di­a­tion prob­lem."-Reuters

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