The government said there has been no meaningful change in the degree of radiation after five-point-five tons of wastewater was leaked from a purification device at Japan’s crippled Fukushima nuclear power plant.

Kim Seong-gyu, director-general of radiation prevention at the Nuclear Safety and Security Commission, said on Thursday that the leak occurred prior to the ALPS purification, and was not directly linked to Japan’s gradual release of wastewater into the ocean.

Both Tokyo and the International Atomic Energy Agency(IAEA) informed Seoul of the incident on the day of the leakage.

Kim said reinforced monitoring has found that radiation detection measurements remained at normal levels even after the leak.

According to plant operator Tokyo Electric Power Company(TEPCO), a worker at the site discovered discharge of wastewater from an exhaust pipe attached to the wall of an incinerator building near Reactor Four, before closing the valve Wednesday morning.