Let's imagine following: For one reason or the other life on Earth evolved much faster and 2 or 3 billions years ago we got equivalent of mid 18 century civilization. At this time U-235 content of total U in ore would be greater than 20%. Say that engineers of this world were processing that ore and some clever guy have worked out how to make metal or pure oxide out of it. Let's assume that product have proven useful for something so large scale production have started. Soon after weird accidents in factories have begun resulting in some "evil flashes of light" after which all factory workers were dying by horrible death within days or weeks. Priests and monks of the time have started to call supernatural powers to help to protect workers and some clever witch have noticed that souls of processed ore hate souls of water and if forced together they start some evil action and peoples are dying. After that work in manufactures have become safer. Soon after someone else have noticed that when processed ore in large quantity is taken together the evil flash happens agaim, there is a mild explosion, stuff smelts around. Poor guy said what he has seen and died soon after. Clever wizard who have redrecords of all this mishaps got good idea and decided to run experiment. He noticed that bringing enough of material together is causing weird and awful effects so he decided to accumulate s lot in dungeon under castle tower (once evil flash was noticed and all workers around died he ordered to stop piling it up. Then he ordered to suspend as much as possible on the top of tower (again evil flashes and death of workers indicated the limit). Then he ordered to drop suspended platform into dungeon. Massive explosion resulted and castle together with surroundings have ceased to exist. Hey presto, a very crude nuclear weapon was invented. After some tweaking it have been proven to work once assembled under enemy castle by several horse driven carriages with contents dropped down purpose dug well. No understanding of science was needed. What do you think about such scenario?