US Patents confirm Uranium warheads
This new hard target warheadhas Tungsten and Uranium penetrator options.
The upgraded 2000 lb warhead is called BLU-116 and can be used in GBU-15, 24, 27, 31 & AGM-130C guided bombs plus BLU-118/B Thermobaric bomb.
e.g. US Patent 6,389,9772000 lb Shrouded Aerial BombBLU-109/B warhead upgradeLockheed Martin 1997-2002