nuclear-news

“I really doubt their seriousness (about decontamination),” said radiation expert Tomoya Yamauchi, a professor at the Graduate School of Maritime Sciences at Kobe University…..

The experts said the government’s goal of human effort achieving a 10 to 20 percent reduction is not ambitious enough.

“A 10 percent reduction doesn’t really mean anything. I mean, 40 percent of the radiation would be reduced just by natural causes, so I think the government is almost saying it is just going to wait for the radioactive materials to decrease naturally,” said Shunichi Tanaka, former chairman of the Atomic Energy Society of Japan.

The main radioactive materials that spewed from the Fukushima No. 1 plant are cesium-134 and -137, the second of which has a half-life of 30 years. Given the relatively short half-life of cesium-134, the total radiation will naturally be halved in four years and fall to one-third in six years, although the threat from the latter will remain for a longer time.

The government is now trying to reduce contamination mainly by using high-power water hoses, known as pressure washers, on structures and removing surface soil and vegetation in limited areas.

But radioactive cesium can find its way into minute cracks and crevices. It is hard to remove, for example, from roofs made of certain materials, or surfaces that are rusted or whose paint is peeling, Yamauchi said.

He has monitored radiation in areas in the city of Fukushima and found that the levels were still quite high after the city performed cleanup operations.

To lower the contamination to pre-March 11 levels, Yamauchi said drastic, and highly costly, efforts by the government are needed, including replacing roofs and removing the surface asphalt of roads.

Tanaka meanwhile pointed out that the government has not even floated a plan for decontaminating the no-go zones where the radiation exceeds 20 millisieverts per year — areas where there isn’t even a timetable for when evacuees will be able to return.

If the government doesn’t speed up the decontamination work, it will be years before the evacuees may be able to return home, he said, adding that the government can’t set a target date because it isn’t sure how the cleanup effort will fare…..

Another issue is the need for communities to reach consensus on where to temporarily store contaminated waste…..

http://www.japantimes.co.jp/text/nn20111109f1.html