Captured by an underwater robot on Saturday, footage released by plant operator Tepco shows for the first time what appears to be melted nuclear fuel inside one of the destroyed Fukushima reactors in Japan.

According to the Japan Times:

Watch:

The footage indicates just how much damage exists inside the three destroyed reactors at the plant. “The search for melted fuel in the two other reactors,” reports the Guardian, “has so far been unsuccessful because of damage and extremely high radiation levels.”