Japan is set to win approval to discharge more than a million cubic meters of treated water from the Fukushima nuclear disaster site into the Pacific Ocean, a contentious plan that’s soured ties with neighbors including China.

The International Atomic Energy Agency’s Director-General Rafael Grossi will visit Japan from Tuesday to deliver a final report on the safety of the process and meet with officials including Foreign Minister Yoshimasa Hayashi. A domestic nuclear regulator is also set to issue a crucial assessment.

Both studies are poised to give backing to Tokyo Electric Power (Tepco) to begin releasing the water — equivalent in volume to about 500 Olympic-size swimming pools — into the sea, a step that’s needed to allow full decommissioning of the Fukushima site following the 2011 earthquake and tsunami that triggered the world’s worst atomic disaster since Chernobyl.