Or, could be Thorium (or something to do with Thorium) since the FibTree's filename was "peace.jpg".

https://en.wikipedia.org/wiki/Thorium-based_nuclear_power

It is difficult to make a practical nuclear bomb from a thorium reactor's byproducts. According to Alvin Radkowsky, designer of the world's first full-scale atomic electric power plant, "a thorium reactor's plutonium production rate would be less than 2 percent of that of a standard reactor, and the plutonium's isotopic content would make it unsuitable for a nuclear detonation." Several uranium-233 bombs have been tested, but the presence of uranium-232 tended to "poison" the uranium-233 in two ways: intense radiation from the uranium-232 made the material difficult to handle, and the uranium-233 led to possible pre-detonation. Separating the uranium-232 from the uranium-233 proved very difficult, although newer laser techniques could facilitate that process.