Study on the production of VAR electrodes from Zircaloy turning lathe chips

Abstract

Zircaloy 4 chips are produced in large quantities during the machining of Zircaloy 4 rods for the PWR fuel elements parts. Currently Zircaloy 4 is a zirconium alloy imported into Brazil and the machining chips scraps poses a challenge to the recycling industry. This paper presents the first step on the recycling processes and the results for the search of an efficient way on the cleaning, quality control and Vacuum Arc Remelting (VAR) electrode fabrication. The process starts with cutting oil washout and is followed by the die pressing of the clean chips. Process evaluation was first made by means the X-ray fluorescence tests in order to define the quality of the scraps. Results indicates the need of the inclusion of a magnetic separation step in the process to withdraw the ferrous alloy present in the scraps. The die pressing of the scraps yield process adequate 1 kg electrodes to be melted in the CCTM prototype scale VAR furnace. The authors also conclude that the samples obtained from the fuel element industry are secondary scraps and suggest them a procedure for the scrap stocking.