Ballooning Behaviour of Zircaloy-4 Fuel Sheaths at a Heating Rate of 0.5 Deg C.S exp -1

摘要

Ballooning tests on Zircaloy-4 fuel sheaths have been done in the temperature range 450 to 900 deg C at a heating rate of 0.5 deg C.s exp -1 . These tests, plus previously reported ones done at 25 deg C.s exp -1 , have been analysed using the strain rate equation: epsilon = A exp(-Q/RT)( exp + sub(a)- exp + sub(i)) sup(n) where A is a constant, Q is the activation energy for the dominant deformation mechanism, R is the gas constant, T is absolute temperature, exp + sub(i) is the internal stress which is controlled by work hardening and recovery processes. The analysis confirms that the above equation can describe transient experiments such as ballooning tests. It also confirms that the description used for the variation of the internal stress in as-received fuel sheaths is reasonable. The activation energy for alpha -phase deformation is about 288 kJ.mol exp -1 .K exp -1 (Q/R = 34700 exp 0 K) and the stress exponent is about 5.3. (Atomindex citation 10:491775)