Tokyo Electric Power Co. reported a massive leak of radioactive rainwater at its crippled Fukushima No. 1 nuclear power plant on March 10.
It said hundreds of tons of contaminated rainwater breached barriers surrounding storage tanks for highly radioactive water and seeped into the ground.
According to TEPCO, the level of rainwater accumulating behind the outside weir of two barriers around storage tanks for contaminated water was 15 centimeters as of 10:30 p.m. on March 9. But the water level had dropped to 7 cm by a little past 8 a.m. on the following day.
Based on the decrease, TEPCO estimated that 747 tons of radioactive rainwater seeped into the soil.