Question

Effect of burnup on ballooning and burst behaviour of zircaloy-4 cladding under simulated loca condition

Answer 1

For the safety evaluation of fuel cladding during the injection of emergency core coolant, simulated loss-of-coolant accident (LOCA) test was performed by using Zr alloy fuel cladding samples. To better understand high burn-up effects, study of hydrogen effects on LOCA-related behavior of high burn-up fuel cladding and their database on experimental results are essentially required. In particular, ballooning and burst behaviors of pressurized Zr alloy tube samples with and without hydrogen pre-charging were mainly investigated under various ramp rate conditions. As a result, pre-hydrided cladding sample showed a lower deformation in ballooned area and lower rupture temperature than as-received cladding sample. Ballooned cladding without hydrogen charging showed no significant difference in mechanical property in spite of a wide range of values for circumferential strain and different balloon shape caused by different heating rate. Pre-hydrided cladding, however, showed an increase in maximum load with increasing heating rate. Strong relationship between hydrogen content and burst behavior during loss-of-coolant accident was analyzed and the mechanism of hardening by hydrogen in zirconium alloy was explained

Answer 2

Explanation:

For the safety evaluation of fuel cladding during the injection of emergency core coolant, simulated loss-of-coolant accident (LOCA) test was performed by using Zr alloy fuel cladding samples. To better understand high burn-up effects, study of hydrogen effects on LOCA-related behavior of high burn-up fuel cladding and their database on experimental results are essentially required. In particular, ballooning and burst behaviors of pressurized Zr alloy tube samples with and without hydrogen pre-charging were mainly investigated under various ramp rate conditions. As a result, pre-hydrided cladding sample showed a lower deformation in ballooned area and lower rupture temperature than as-received cladding sample.