Thursday, 29 September 2011

Japan sizes up cost of cleanup at Fukushima

Japan faces the prospect of removing and disposing 29 million cubic meters of soil contaminated by the world's worst nuclear crisis in 25 years from an area nearly the size of Tokyo, the environment ministry said in the first official estimate of the scope and size of the cleanup.

Six months after the March 11 earthquake and tsunami triggered reactor meltdowns, explosions and radiation leaks at Fukushima Daiichi nuclear power plant on Japan's northeast coast, the size of the task of cleaning up is only now becoming clear.

Contaminated zones where radiation levels need to be brought down could top 2,400 square kilometers, sprawling over Fukushima and four nearby prefectures, the ministry said in a report released on Tuesday.

Tokyo Metropolitan prefecture has a total area of 2,170 square kilometers.

The environment ministry has requested an additional 450 billion yen (US$5.88 billion) in a third extra budget for the year to next March that the government aims to submit to parliament in October, Kyodo news agency reported.

The government has raised 220 billion yen to be used for decontamination work, but some experts say the cleanup bill cost reach trillions of yen.

If a 5-centimeter layer of surface soil, likely to contain cesium, is scraped off affected areas, grass and fallen leaves are removed from forests, and dirt and leaves are removed from gutters, it would amount to nearly 29 million cubic meters of radioactive waste, the document showed.

This would be enough to fill 23 baseball stadiums with a capacity of 55,000 spectators, and the government must decide where to temporarily store such waste and how to dispose of it permanently.

Japan has banned people from entering within a 20km radius of the plant, located about 240km northeast of Tokyo and owned by Tokyo Electric Power Co. Some 80,000 people were forced to evacuate.

The ministry's estimate assumes that cleanup efforts should be mainly in areas where people could be exposed to radiation of 5 millisieverts or more annually, excluding exposure from natural sources.

The unit sievert quantifies the amount of radiation absorbed by human tissues and a mSv is one-thousandth of a sievert. Radiation exposure from natural sources in a year is about 2.4 mSv on average, the United Nations atomic watchdog said.

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