 Titanium metal and its alloys have a wide range of applications , where the corrosion resistance , the heat stability and the low density ( light weight ) are of benefit . The foremost use of corrosion @-@ resistant hafnium and zirconium has been in nuclear reactors . Zirconium has a very low and hafnium has a high thermal neutron @-@ capture cross @-@ section . Therefore , zirconium ( mostly as <unk> ) is used as cladding of fuel rods in nuclear reactors , while hafnium is used as control rod for nuclear reactors , because each hafnium atom can absorb multiple neutrons . 
