Pellet Bed Reactor for nuclear thermal propelled vehicles

Abstract

The Pellet Bed Reactor (PeBR) concept is capable of operating at a high power density of up to 3.0 kWt/cm3 and an exit hydrogen gas temperature of 3000 K. The nominal reactor thermal power is 1500 MW and the reactor core is 0.80 m in diameter and 1.3 m high. The nominal PeBR engine generates a thrust of approximately 315 kN at a Specific Impulse (Isp) of 1000 s for a mission duration to Mars of 250 days requiring a total firing time of 170 minutes. Because of its low diameter‐to‐height ratio, PeBR has enough surface area for passive removal of the decay heat from the reactor core. In addition, the reactor is equipped with two independent shutdown mechanisms; 8‐D4C safety rods and 26 BeO/B4C control drums; each system is capable of operating and scraming the reactor safely. The core k‐effective at Beginning of‐Life (BOL) is about 1.07 and in case of water immersion the reactor core is subcritical (k‐effective of 0.93). Due to the absence of core internal support structures, the PeBR can be fueled and refueled in orbit using the vacuum of space. These unique features of the PeBR provide for safety during launch, simplicity of handling, deployment, and end‐of‐life disposal, and vehicle extended lifetime.