TOKYO, Aug. 15 (Xinhua) — About 25 tons of radioactive water leaked into the damaged Fukushima Daiichi nuclear power plant, the plant’s operator said, a week after the latest discharge of radioactive water into the sea began.

According to the Tokyo Electric Power Company (TEPCO), the nuclear-contaminated water that leaked from a surge tank connected to the reactor building of Unit 2 was to be collected in a tank that holds overflow water from the spent fuel pool.

The leaked water accumulated in the first basement of the reactor building and caused a further rise in the contaminated water level already present in the region, TEPCO said on Tuesday, confirming that the contaminated water had not leaked outside the reactor building.

According to TEPCO, the leak was first discovered last Friday when a drop in the water level in the surge tank was detected. Upon further investigation, the company found that water was flowing into a drain in a room on the third floor of the reactor building.

The company plans to use a remote-controlled robot to measure radiation levels in the room by Friday to determine the exact location and cause of the leak. As part of the investigation, the cooling pump for the swimming pool was temporarily turned off.

On March 11, 2011, the Fukushima Nuclear Power Plant was struck by a magnitude 9.0 earthquake and a subsequent tsunami. Nuclear meltdowns and releases of radioactive radiation occurred, triggering a level 7 nuclear accident, the highest level on the International Nuclear and Radiological Event Scale.

When nuclear fuel is cooled in reactor buildings, the power plant produces large quantities of water contaminated with radioactive substances. The contaminated water is now stored in tanks at the nuclear power plant.

Despite fierce opposition at home and abroad, the discharge of water contaminated by the Fukushima atomic bomb into the sea began in August 2023, and the eighth round of discharges into the sea began last week.

In the 2024 fiscal year, TEPCO plans to discharge a total of 54,600 tons of contaminated water, which contains about 14 trillion becquerels of tritium, in seven rounds.

Amid growing Japanese public concerns about the plant’s credibility and safety following a series of accidents at the stricken power plant, TEPCO and the Japanese government have been repeatedly accused of improper handling of the contaminated water.■