 This deadly stuff is traipsed around the country to Sellafield. And for those of you not familiar, Sellafield is the largest nuclear site in Europe and the most complicated nuclear site in the world. By its own admission, it is home to one of the largest inventories of untreated waste, including 140 tons of civil plutonium, the largest stockpile in the world. To put that into perspective, between 5 and 10 kilograms of plutonium