Effect of of Pre-hydriding on the Burst Behavior of the Zirconium Cladding under Loss-of-Coolant Accident Condition

Abstract

To investigate the effects of hydrogen on the rupture behavior and mechanical property of ballooned-zirconium cladding after a loss-of-coolant accident, simulated loss-of-coolant-accident tests were carried out using pressurized-zirconium-tube samples with and without hydrogen pre-charging. A pre-hydrided cladding sample showed lower deformation in the ballooned area and lower rupture temperature than the 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 of a different balloon shape caused by a different heating rate. Pre-hydrided cladding, however, showed an increase in maximum load with increasing heating-rate. The strong relationship between hydrogen content and burst behavior during the loss-of-coolant accident was analyzed and the mechanism by which hydrogen hardens zirconium alloy was explained.