Reaction-time response of aircraft crash

The safety related structures of a Nuclear Power Plant (NPP) are required to be designed for the impact of aircraft. The reaction-time response is usually obtained assuming the target to be rigid. The assumption is claimed to be conservative in the case of stiff structures. The effect of target yielding has been studied by considering an aircraft crash upon the outer containment of an NPP. It has been observed in this investigation that the assumption of a rigid target is unconservative for some of the cases. It is usually assumed that variation in crushing strength has very little effect on the reaction from the target. However, the sensitivity analysis for reaction-time response indicates that both linear mass density and crushing strength are sensitive in affecting the reaction from the target, depending upon the characteristics of the aircraft and the striking velocity. The concept of confidence level has been investigated in relation to inclined targets also and confidence curves are obtained for aircraft.