The U.N. nuclear watchdog chief began a three-day visit to Japan on Tuesday for a trip that will include his first visit to storage facilities for soil contaminated in the 2011 Fukushima disaster.

It is the fifth official visit to the country by Rafael Grossi, head of the International Atomic Energy Agency (IAEA).

The organization is monitoring the decades-long process to decommission the Fukushima No. 1 nuclear plant, which went into meltdown after being hit by a tsunami in the worst nuclear disaster since Chernobyl.