Nuc waste. A green slime that gives off toxic gas. Need a hazmat suit to be near and a bucket-like item to pick it up. Bucket item would be expensive so it can't be picked up and thrown away. Radio waste would need to be stored somewhere like real waste. Have a slot on the Nuc GUI for radio waste and if it goes up over 100 the reactor stops. Something like that. Probs never get in tho.
There's no radiation because, I believe, the AoE detection needed for it would eat cpu for breakfast.
Wonder if it could be coded like water and lava...except not respond to gravity and look like normal air or something? The source block would be a visable green goop and the flow blocks look like air. Would be detected however the avatar detects that it's in lava/water.
Wonder if that could be done for gases. Someone wanted smog I think