According to Kyodo News, Tokyo Electric Power Co. (TEPCO) said Monday that the strontium 90 activity level was about three times higher than the national standard after ALPS was used to clean the contaminated water from the Fukushima Daiichi nuclear power plant. However, it was below the standard level in subsequent tests. Tepco believes the phenomenon is temporary and it is unclear why。

According to Tepco, the activity of strontium 90 in treated water sampled on July 28 was 93 becquerels per liter, compared with the national standard of 30 becquerels. Since the activity of strontium 90 is declining smoothly in the middle of the treatment process, TEPCO believes that the reason may lie in the latter half of the process. On August 4, the activity of strontium 90 in the sampled water was 2.7 becquerels.

It is reported that the excess water is stored in the storage tank and will be purified again. ALPS also has five other units, and Tepco says the purification of contaminated water will not be affected. Tepco plans to start discharging the treated water into the sea around spring next year.

On March 11, 2011, a 9.0 magnitude earthquake and massive tsunami struck off the northeastern coast of Japan. As a result of the earthquake and tsunami, a large amount of radioactive material leaked from the Fukushima Daiichi nuclear power plant.

On April 13, 2021, the Japanese government decided to release a large amount of nuclear water from Fukushima into the sea. Under the plan, the nuclear water will be diluted with seawater and discharged about 1 kilometer offshore through an undersea tunnel. The move was strongly opposed by the Fukushima Prefecture Fisheries Association and the National Federation of Japanese Fisheries Associations, as well as the international community.