Lab (structure)
The Lab is a small building made out of 
Über Concrete, that is constantly turning into moldy debris. The lab can only found in the plains biome.
Inside the structure, the player can find a Dud. Breaking a few blocks down, the player can find a small bunker with some shelves containing 3 hazmat crates, 1 supply crate, several recorders (placed on the shelves), and 2 iron crates with radiation related items such as 
tungsten reachers and various nuclear materials.
Loot
A Vitrified Nuclear Waste Barrel on one of the shelves, and items found inside of the iron crates which as explained above is usually just radiation-related items like nuclear fuel, billets, ingots and rods of other nuclear materials.
Dangers
The Vitrified Nuclear Waste Barrel in the bunker gives off a tiny bit of radiation.
Some of the lab tiles are cracked, meaning they will give off asbestos particles.