Total Emissivity of CANDU Fuel Sheath at High Temperatures

Abstract

For the assessment of fuel behaviour during reactor accidents involving high temperatures, a knowledge of the emissivity of the fuel sheath is required. Current data on the emissivity of Zircaloy-4 fuel sheaths are limited to 1423 K only. This paper describes the development of a technique and the experiments conducted to determine the total emissivity of Zircaloy-4 CANDU (CANada Deuterium Uranium) fuel sheaths in argon and in steam for up to 120 s at temperatures ranging from 1423 K to 1973 K. The results show that in this temperature range, the total emissivity of an unoxidized, metallic bright fuel sheath in argon remains constant at a value of 0.20 compared with a constant value of 0.82/or a steam-oxidized black sheath/or oxidation time up to 120 s. The current data are in good agreement with reported measurements available up to 1423 K.