Yes there is segrigation!!! The surface of a fresh casting (800+ kgs) can be 20 or more R/hr... contact dose rate mostly from the Protactinium (234) beta's. There are several Army documents (safe handling of depleted uranium) which identify such hazards. William Lorenzen Children's Hospital Boston, MA (617) 355-7516 lorenzen_w@a1.tch.harvard.edu