US Patents confirm Uranium warheads
This new hard target warhead has 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 6,389,977 2000 lb Shrouded Aerial Bomb BLU-109/B warhead upgrade Lockheed Martin 1997-2002