I was on one of the Space Shuttle Columbia's recovery team, at least one of the hydrazine tank was intact and still half full ... It was incredible that some of the items were completely burnt up, while others looked like quite shiny and new.
Thats interesting. There is a heat shield design which uses liquid water to dispose of heat at the back of a heat shield. A pressure relief valve keeps the vaporisation temperature higher than normal to ensure a lot of heat is carried away by water vapor.
So the half full hydrazine tank is actually working as an efficient heat shield and objects like that may be more likely to reach the ground.