Tokyo Electric Power Co. reported a massive leak of radioactive rainwater at its crippled Fukushima No. 1 nuclear power plant on March 10.
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.
The plant operator measured levels of beta-ray-emitting materials in the leaked water and detected a maximum reading of 8,300 becquerels per liter at one location. The average level of radioactivity at five sample locations was 2,300 becquerels per liter, according to TEPCO.
Highly contaminated water also leaked from the same area and seeped into the ground in summer 2013. As a result, TEPCO paved the surrounding area with asphalt to prevent a recurrence in the event of radioactive water spilling out.
In the latest leakage, workers discovered bubbles at the junctions of side ditches in the area. Officials said this indicated that contaminated rainwater had seeped through the junctions and into the ground.
According to the plant operator, although highly contaminated water with radioactive levels of tens to hundreds of millions of becquerels per liter is stored near the leakage site, no problems have been reported with the tanks and pipes of those nearby storage facilities.