Special aspects of deep transient mode dynamics in open-loop bimodal space nuclear power systems

Bimodal systems as a special class of space-based nuclear power systems implement within a single structure the concept of continuous generation of power and intermittent generation of thrust. The primary criterion for practicability of a design concept is confirmation of feasibility of achieving within a specified time the target temperature of the working medium at the reactor outlet when switching to the thrust mode. The paper describes results of computational dynamics studies for three types of bimodal power systems, which were being developed in RF in 1990-2010 based on the well-known power systems Romashka, Enisei and Topaz. It discusses some special aspects involved in simulations of thermal processes. It also provides recommendations which make it possible to meet the requirements for the dynamics of switching to the thrust mode.