The operators of the Fukushima Daiichi nuclear plant in Japan have flooded an underground trench with a milky white dye in their efforts to find the source of radioactive water, which is leaking into the ocean at a rate of seven tons an hour. However, after four hours the dye had failed to indicate the source. Earlier, rescue workers had attempted to plug the leak with concrete, sawdust, and shredded newspaper.
Read it at Kyodo News