Nuclear reactors of “Proryv” project are positioned as the basis for large scale nuclear energetics with inherent safety, which in particular means “eliminating accident at NPP that require evacuation let alone resettlement of population”, which includes cases of multiple malfunctions. The decay heat removal from the reactor core and prevention of the fuel pins overheating is one of first key questions of safety justification problem. On the base of parametric study using engineering thermal-hydraulics code it is shown how to advance efficiency of decay heat removal through modification of reactor upper plenum design.