Grossi has been pushing for a safety agreement to protect the facility, amid repeated accusations by Moscow and Kyiv of shelling the site of the power station.
The Rolls-Royce micro-nuclear reactor is seen as a promising method of providing a power source for a long-term human presence on the Moon.
Ukrainian officials have accused Russian forces of compromising safety by shelling the site of the plant, forcing power cuts during air strikes and flouting safety measures.
Both Kyiv and Moscow have accused each other of shelling the Zaporizhzhia nuclear power plant.