Analytical Quality Control in the Production of Nuclear Grade Zirconium and its Alloys

The chief application of zirconium metal &zircaloys
is in nuclear reactor engineering as cladding material
for the fuel elements and as structural material in the construction of reactor cores. The selection is based on considerations of low neutron absorption cross section, fabricability, corrosion resistance and mechanical stre-ngth at elevated temperatures. These properties are however sensititive to impurity levels and alloying compositions. For example, for neutron economy the hafn-ium and boron contents should be within 200 ppm and 0.5 ppm respectively; for corrosion resistance the aluminium, carbon and nitrogen tolerances are respectively only 75ppm, and 500ppm and 50ppm; and for ease of fabrication the maximim permissible oxygen content is 1500 ppm. In
the large scale production of zirconium sponge and zircaloy ingots, it becomes therefore essential to have a strict control of impurity levels in the successive stages of the batchwise production, in order to ensure consistency of quality and performance in the finished product.