Why not pump water from the trench before it overflows, and store it somewhere where it can be dealt with safely?
TEPCO is proposing to do just that. It has said today that it plans to pump 11,500 tonnes of contaminated water from the trenches and turbine halls and dump it in the ocean, starting tomorrow. Though it contains radioactivity at 100 times the legal limit, TEPCO claims that dumping it out at sea will dilute it to safe levels. In a press release, TEPCO announced that it plans to dump 10,000 tonnes of water contaminated with low levels of radiation.
Andrew Sherry of the Dalton Nuclear Institute in Manchester, UK, told New Scientist that with US and French assistance, TEPCO is building a 6000-tonne water tank into which contaminated water will be sent for treatment in an ion-exchange unit that will decontaminate the water by scavenging the radioactive ions and replacing them for harmless ones. "Effectively, they are having to manage this contaminated water and treat it," he says.
Does the contamination of seawater pose a health threat?
So far, most of the radioactivity has come from iodine-131 which has a half-life of eight days. So within a month or so, the levels of iodine entering the sea will have fallen by a factor of 16. Some researchers contacted by New Scientist believe that more serious and long-lasting problems may have been caused by a plume of airborne radioactive material that blew north-west in the early days of the crisis.
The plume deposited radiation across Fukushima prefecture, with the worst contamination seen in the village of Iitate. Because the fallout included caesium-137, which takes 30 years to decay to half the original amount, farmers in "hotspots" may not be able to grow or sell their produce for many years. This is what happened in parts of western Europe after the Chernobyl nuclear accident in Ukraine in 1986.
If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.