November 26, 2021

On April 25, it was learned that Tokyo Electric Power Company (TEPCO) has decided to start an oceanographic survey by the end of the month to lay an undersea tunnel for the release of treated water from the Fukushima No. 1 Nuclear Power Plant. After completing the survey, the company will start laying the tunnel, aiming to start releasing the water in spring 2023. According to the officials, TEPCO had initially expected to start the survey in September, but was forced to postpone it due to difficulties in forming a consensus with neighboring municipalities.

In August, TEPCO announced a process plan to construct an undersea tunnel, run pipes through it, and drain the water into the sea about one kilometer offshore from the plant. In this submarine survey, in addition to magnetic surveys to ascertain the condition of the seabed, including confirmation of unexploded ordnance and other hazardous materials, diving surveys will be conducted as necessary. A submarine boring survey using a workboat will also be conducted.

The submarine tunnel is expected to be about 2.5 meters in diameter, and pipes will be cut through the bedrock of the seabed from the vicinity of the No. 5 and No. 6 reactors at the plant. We had considered the idea of draining the water into the sea near the east side of the plant, but we chose to go offshore where the tritium contained in the treated water would be more diffused. It is believed that the decision was based on the fact that there are no fishing rights in the waters about one kilometer offshore and that there would be little opposition from fishermen concerned about harmful rumors.

On the 17th of this month, the government announced the results of its assessment that the radiation dose in the surrounding waters due to the release of treated water was far below the safety standards set by the government and international organizations, and that the impact of radiation on the surrounding residents and the environment was “extremely minor.

The decision to release the treated water was made in April this year by the then government of Yoshihide Suga, and Prime Minister Fumio Kishida, who inspected the plant in October, said that it was a very important issue that could not be postponed.