Pic: AP.

TOKYO (AP) — Highly radioactive water has overflowed from a storage tank at Japan’s crippled nuclear power plant, but the operator says it did not reach the Pacific Ocean.

The operator, Tokyo Electric Power Co., said Thursday that the leak involved partially treated water from early in the crisis, meaning it was more toxic than previous leaks. Three reactors melted at the Fukushima Dai-ichi plant following the 2011 earthquake and tsunami, with radioactive water partially recycled and stored in more than 1,000 tanks.

TEPCO says about 100 tons of the contaminated water overflowed through a rainwater drainage pipe, where plant workers attached a garbage bag to contain the leakage. TEPCO says the leak has since stopped after workers closed the valves and did not escape into the Pacific.