This sounds familiar, did they get advice from BP? The Guardian reports:
Engineers battling to contain the crisis at Japan‘s Fukushima nuclear power plant appeared to have turned an important corner last night after they stopped highly radioactive water from leaking into the ocean from one of the facility’s crippled reactors.
Workers struggling to halt the leaks successfully used a mixture of sawdust, newspaper, concrete and a type of liquid glass to stem the flow of contaminated water near a seaside pit, said the plant’s owner, Tokyo Electric Power Co (Tepco).
Earlier efforts involving cement, an absorbent polymer and rags were unsuccessful in plugging the leak, which was discovered on Saturday, while radiation of more than 7.5 million times the legal limit for seawater was found just off the earthquake-hit plant.
In a sign of Tepco’s desperation, it breached its own regulations on Monday by beginning an intentional discharge of 11,500 tonnes of less contaminated water into the Pacific to make space for the highly radioactive liquid that was seeping out in an uncontrolled manner.