Nuclear Thermal Rocket Simulation in NPSS

Abstract

Four nuclear thermal rocket (NTR) models have been created in the Numerical Propulsion System Simulation (NPSS) framework. The models are divided into two categories. One set is based upon the ZrC-graphite composite fuel element and tie tube-style reactor developed during the Nuclear Engine for Rocket Vehicle Application (NERVA) project in the late 1960s and early 1970s. The other reactor set is based upon a W-UO2 ceramicmetallic (CERMET) fuel element. Within each category, a small and a large thrust engine are modeled. The small engine models utilize RL-10 turbomachinery performance maps and have a thrust of approximately 33.4 kN (7,500 lbf ). The large engine models utilize scaled RL-60 turbomachinery performance maps and have a thrust of approximately 111.2 kN (25,000 lbf ). Power deposition profiles for each reactor were obtained from a detailed Monte Carlo N-Particle (MCNP5) model of the reactor cores. Performance factors such as thermodynamic state points, thrust, specific impulse, reactor power level, and maximum fuel temperature are analyzed for each engine design.

Numerical investigation of heat transfer characteristics of moderator assembly employed in a low-enriched uranium nuclear thermal propulsion reactor

“…However, an accurate prediction of peak temperature in the sensitive region remains a significant challenge due to the complex heat transfer mechanism involved in the two kinds of assemblies. This study's fuel and moderator assembly geometry is based on the NERVA-derived design (Belair et al, 2013). The fuel assembly features 19 coolant channels with a diameter of 0.257 cm.…”

“…NTP reactor designs are grouped into high-enriched uranium (HEU) and low-enriched uranium (LEU) designs according to the different enrichment of the nuclear fuel used. A few decades of the cold war between the United States and the Soviet Union had witnessed the amount of mature and effective numerical and experimental work (Belair et al, 2013;Khatry et al, 2019;Graham, 2020) on HEU design. However, recent efforts focus on designing a feasible engine that relies on LEU fuel due to its lower cost and nuclear proliferation risk (Venneri and KIM, 2015a;Venneri and KIM, 2015b;Gates et al, 2018).…”

A Coupled Approach to the Design Space Exploration of Nuclear Thermal Propulsion Systems

“…In addition to these targets, ranges for inner reactor chamber pressures and temperatures are defined as shown in Table 3. These ranges constrain the operating envelope of the NTP system and are based off realistic inner reactor pressure chamber conditions taken from [15].…”

“…First, a tank temperature and pressure are established based on literature values for similar systems [16], these are treated as constant for the purposes of this calculation. Sweeps are then defined for three key turbomachinery characteristics as detailed in Table 4 based on literature values [15]. With these ranges defined, the next step is to walk through the simplified cycle analysis of the propulsion system to arrive at the reactor inlet conditions for each of the different combination of characteristics and for each mass flow rate which allows for the thrust target to be met as detailed previously.…”

Parametric Analyses of a 75 kN Thrust Class Composite Fuel Based NTR Engine

“…The hydrogen flow rate is calculated to range from 8.35 to 9.75 kg/s (18.4 to 21.5 lb m /s). This TPA is a single shaft design with a two stage centrifugal pump with shrouded impellers, hybrid ceramic bearings, and a two-stage axial flow turbine 22 . Detailed integration issues involved with using the RL60 turbopump, however, are beyond the scope of this work.…”