MCNP Simulation of the Canadian Super-Critical Water Reactor’s Liquid Injection Shutdown System

Abstract

The Canadian Super-Critical Water Reactor (SCWR) uses a vertical pressure-tube concept, with D2O moderator, super-critical H2O coolant and thorium-based fuel. To further recent MCNP modelings of the SCWR core, it was necessary to simulate a Liquid Injection Shutdown System (LISS), which involves reactivity reduction by liquid neutron poison injection. By utilizing previous studies on similar reactor concepts, a LISS has been modeled in MCNP for the SCWR, demonstrating sufficient and timely reactivity reduction. In particular, the model propagates physically realistic neutron poison jets over multiple time steps, thereby simulating a realistic LISS in MCNP.\