The operator of Japan's crippled nuclear power plant says that about 45 tons of highly radioactive water leaked from a purification device over the weekend, and some may have drained into the ocean.
The leak comes as Tokyo Electric Power Co. aims to bring the damaged Fukushima Dai-ichi plant to a cold shutdown by year-end.
A pool of radioactive water was discovered midday Sunday around a decontamination device, TEPCO said in a statement. After the equipment was turned off, the leak appeared to stop.
Later, workers found a crack in a concrete barrier leaking the contaminated water into a gutter that leads to the ocean. TEPCO estimates that about 300 liters leaked out before it was blocked with sandbags.
Officials were checking whether any water had reached the ocean.