Gen-1 NTP Ground Test Concept of Operations

Nuclear Thermal Propulsion (NTP) is an enabling technology for various conceptual missions due to its unique monopropellant capability offering flexible concepts of operation. Recent studies have examined different propellants for these engines which include hydrogen, ammonia, and methane, each of which carry with them their own unique set of challenges and advantages. However, due to ever changing and stricter nuclear regulations, ground testing these systems is expensive and challenging. New concepts such as the High-Pressure Real-Time (HPRT) Exhaust Capture System enables full-scale ground testing of NTP engines while also complying with regulatory requirements.

The proposed HPRT exhaust capture system concept requires significant nozzle truncation of ground test engines which substantially affects the turbomachinery operation due to reduced gained fluid enthalpy in the regenerative cooling section. The mitigation strategy proposed by this work is to add a preheater prior to the regenerative cooling section to supply the lost enthalpy and enable test-like-you-fly turbomachinery operation during these tests.

A recommended test campaign is also part of this work that incrementally reduces risk with each subsequent test. These tests aim to ensure proper engine operation with conservative temperatures and power levels, verify control system operation via balanced sub-nominal operation, high-temperature material limits test via aggressive operation, and repeatable full tests to demonstrate nominal engine operation and multiple restart capability prior to a flight test.