Analytical quality Control in the Production of Nuclear grade Zirconium and its Alloys

Abstract

THE chief application of zirconium metal and 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 strength at elevated temperatures. These properties are, however , sensitive to impurity levels and alloying compositions . For example , for neutron economy the hafnium and boron contents should be within 200 ppm and 0'5 ppm respectively : for corrosion resi-stance the aluminium , carbon and nitrogen tolerances are respectively only 75 ppm , 500 ppm and 50 ppm ; and for ease of fabrication the maximum permissible oxygen content is 1500 ppm. In the large scale production of zirconium sponge and zircaloy ingots, it becomes there-fore 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.