The release is unlikely to begin for at least two years, but has already sparked opposition from local fishing communities and concern in Beijing and Seoul.
Only nine of Japan's 33 remaining commercial reactors have been approved for restarts under post-Fukushima safety standards and only four are operating, compared with 54 before the disaster.
Nuclear power supplied just 6% of Japan's energy needs in the first half of 2020 compared with 23.1% for renewable sources - far behind Germany's 46.3% - and nearly 70% for fossil fuels.