A group of South Korean experts arrived in Japan on Sunday to check the release of wastewater from the crippled Fukushima nuclear power plant.

The Nuclear Safety and Security Commission said on Monday that three experts left for Japan the previous morning to visit the field office of International Atomic Energy Agency(IAEA), which was opened at the plant last month to monitor the safe discharge of treated radioactive water into the Pacific Ocean.

The visit comes three days after plant operator Tokyo Electric Power Company started the discharge.

The experts reportedly include officials from the Korea Institute of Nuclear Safety, who were part of a South Korean inspection team that visited the plant in May.

The length of their stay and their activities are expected to be decided through consultation with the IAEA, which earlier reached an agreement with Seoul as well as Tokyo on biweekly visits by South Korean experts to the agency’s field office at the plant.