The fbomb.zip file you have requested: Modifications / Miscellaneous / Fusion Bomb - 266.35kb is not available. Perhaps try browsing all files for the game Civilization IV: Beyond the Sword and upload any files you want to share or are missing. This is the only information we could locate:
For more information on Civilization IV, visit Civilization4.filefront.com At only 350 hammers, this is a cheap weapon of mass destruction. It doesn't need any resources either. But the downside is that it only affects 1 tile/plot on the map in stead of the 9 that the ICBM affects.