nuclear-news

Japan’s emergency experimental methods to stem flow of radioactive water

Japan Nuclear Plant’s Battle to Contain Radioactive Water Tepco Builds Sunken Barrier to Ring-Fence Site, but Water May Have Already Overtopped Wall  WSJ, 6 Aug 13, by  MARI IWATA  and  PHRED DVORAK   “…………As an emergency measure, Tepco last month started to inject the ground near the coast with chemicals that hardened it into an underground barrier. But since then, groundwater levels in the area have risen faster, as they hit the barrier. Recently, Tepco has found that the groundwater has risen to around a meter below the surface—already above the level of the underground barrier, which starts 1.8 meters down.Now, Tepco is planning to pump out some of the water that’s built up behind the barrier, and store it as well. It’s preparing to extend the underground hardened-earth barrier in a ring around the most heavily contaminated section of coastline, in hopes of heading groundwater off before it can flood in. Tepco is also proposing to cap that ringed section with gravel and asphalt, so nothing gets out. The operator is hoping to get an initial ring of hardened ground done by October.

The company has some other more experimental ideas on the table as well. One involves surrounding the contaminated reactor buildings with a shield of frozen soil.

But there’s a risk to changing the flow of groundwater in the ways that Tepco is considering, said Tatsuya Shinkawa, nuclear accident response director of the Ministry of Economy, Trade and Industry, at a news conference last month. The water could pool dangerously underground, softening the earth and potentially toppling the reactor buildings, he said. Tepco should also try things like using robots to fix cracks in the reactor buildings where the water is likely seeping through.

Freezing soil has its own problems, said Kunio Watanabe, a geology professor at Saitama University. The technology, which is used in civil engineering to dig tunnels, may be able to cut down the amount of groundwater entering the contaminated site, but it is expensive. “You’ll need hundreds of millions of yen to build a system,” Mr. Watanabe said. “You’ll also need a large amount of electricity to maintain the ice walls.”….. http://online.wsj.com/article/SB10001424127887323420604578651713545887032.html

August 7, 2013 - Posted by Christina Macpherson | Fukushima 2013, Japan, Reference, water