Thermal Stress Analysis of Nuclear Containment Wall under Aircraft Crash
Nuclear energy presently contributes more than 17% of global energy demand. In view of the recent nuclear disasters, safety concern in nuclear structures is on the rise. In this study, safety analysis of 1.2m thick outer containment of a typical Nuclear Power Plant has been carried out using ABAQUS/Implicit finite element code. Areal nuclear containment BWR Mark III has been considered in the present study. The height and diameter of the containment wall is 46m and 42m respectively. First, the impact load is applied on the containment using Riera force history curve of Boeing 707-320, after 0.2 sec nodal temperatures were increased following the proposed jet fuel curve to imitate fire as a result of fuel burning. Combined effect of impact and heat has been used to study thermal stress variation.
As the fuel is stored in the wings of the plane, the effect of fire is assumed to trigger as soon as the wings hit the outer face of containment wall. From Riera force history curve, time delay between plane’s first contact and wing contact with the containment wall was assumed to be 0.2 second. The impact location of the aircraft was considered at mid-height of the containment wall as more deformation was observed in this location. The fire effect was considered to be most severe near the base of the containment as the most of the fuel will immediately flow down to the bottom of containment after impact. The behaviour of concrete and reinforcement has been incorporated using Concrete Damaged Plasticity model and Johnson Cook elastic-visco plastic model respectively. The material parameters for concrete and reinforcement at elevated temperature have been taken from Eurocode 2. From the study it may be concluded that there was no global damage in the containment wall due to impact, heat and thermal stress, but some local damage on the outer face of the containment wall has been occurred.
Keywords - Impact, Aircraft Crash, Nuclear Containment, Fire Resistance, Fire Endurance Time, Thermal Stress.