If the explosion at Khmelnitsky was conventional, it would be one of the half dozen or so biggest non-nuclear explosions of all time, anywhere on Earth. You'd think you'd need all the explosive power of a large depot made up into one super bomb to achieve that and that plainly is not what we are describing.
MOAB explosion does not compare
Again...
At the time of the gulf wars there were reports indicating that there are two kinds of DU, one dangerous, the other not so much. The Brits appear to have gone with the dangerous kind.