The Tokyo Electric Power Company reported Tuesday that 750 tons of contaminated rainwater may have leached into the ground around a water tank holding area at the Fukushima Daiichi nuclear power station, but that the water was unlikely to reach the ocean.
On the four-year anniversary of Tohoku or the Great East Japan Earthquake, cleanup work continues to focus on efforts to contain the flow of water in and out of the facility that was hit by a 9-magnitude earthquake on March 11, 2011, and then hit again by the 45-foot tsunami event the earthquake set into motion.
It was the largest earthquake in Japan's history. More than 18,000 people died and more than 200,000 were left homeless – some because their homes were destroyed and others because they lived too close to the nuclear power plant, where four reactors were damaged and explosions in the Unit 1 and 3 reactor buildings made cleanup efforts that much harder.
Groundwater now seeps into the damaged buildings and even rain water on the site quickly becomes toxic. TEPCO is attempting to contain water movement by freezing the soil under the plant to create a wall of ice – an effort that is ongoing.
TEPCO said that approximately 750 tons of rainwater containing Strontium90 may have seeped into the ground around the "H4" tank area.
There was heavy rain in Fukushima and rainwater had accumulated around the "H4" tank area, where a simple outer wall was built to prevent the spread of any leakage from the inner wall, which is built for the purpose of protecting the tank area. The outer wall has a protective sealing which is designed to contain water, but it was possible that some water may have seeped out from some seams, the company said in a statement.
As the company analyzed rainwater within the outer wall, gross beta levels, which is the total amount of nucleotides emitting beta rays such as Strontium90 ranged from 150 to 8,300 Becquerels per liter. Cesium levels were not detected, TEPCO said.
It has been confirmed that there is no inflow into the closest drainage channel located to the sea side of "H4" area, nor any significant change in the monitored radioactivity level in the drainage, TEPCO said.