Workers at Japan’s quake-hit nuclear plant are using dye to try to trace the route of highly radioactive water flowing from a reactor into the sea.
The source of the leak was identified at the weekend as a 20cm (8in) crack in a concrete pit at reactor 2.
Earlier efforts to plug the hole using a highly absorbent polymer failed.
The plant’s operator has been been struggling for more than three weeks to regain control after a huge quake and tsunami knocked out cooling systems.
The BBC’s Roland Buerk in Tokyo says the emergency workers still face a dilemma of pumping water in to the reactors, to try to stop them overheating.
If they do, he says, the risk is that there is more contaminated water around the plant that could escape into the environment.
Japan’s top government spokesman said…