UPDATE AS OF 11:30 A.M. EDT, WEDNESDAY, APRIL 6:
TEPCO has stopped a leak of highly radioactive water from the site into the Pacific Ocean. TEPCO had been trying various means to plug the leak in a concrete enclosure that carries electric cables since it was discovered Saturday. Pouring concrete and later an absorbent polymer into the enclosure were unsuccessful.
On Monday, workers injected a colored liquid tracer into the system of enclosures to determine the flow path of the water. It showed that the radioactive water may be leaking from a cracked pipe, and then seeping through gravel into the concrete enclosure. Additional testing showed leakage from the crack in the enclosure into the ocean.
Beginning yesterday, TEPCO injected approximately 1,600 gallons of liquid glass into the system, which stanched the flow of water. TEPCO is considering injecting more liquid glass into the area as a preventive measure.
Workers continue to inject cooling water into reactors 1, 2 and 3 and to the used fuel storage pools at reactors 1-4. Radioactive water in the turbine buildings continues to hinder efforts to fully restore cooling functions.
Some residents of the 20-kilometer (12.5-mile) evacuation zone around Fukushima Daiichi may be permitted brief visits to retrieve personal items from their homes. The Japanese government is analyzing radiation data and is expected to draft a plan for the visits.