You can find a recipe to craft a Radioactive Capsule in the northeast somewhere. It'll be a site surrounded by a fence, that has a hatch in the middle. It'll have a recipe for it. You will need to gather radioactive materials from the cave in the southeast of the map. However, I haven't done this myself quite yet, so if there's a walkthrough, I would recommend looking for one, and preparing a Hazmat Suit.