Ground Testing a Nuclear Thermal Rocket: Design of a Sub-scale Demonstration Experiment

Abstract

In 2008, the NASA Mars Architecture Team found that the Nuclear Thermal Rocket (NTR) was the preferred propulsion system out of all the combinations of chemical propulsion, solar electric, nuclear electric, aerobrake, and NTR studied. Recently, the National Research Council committee reviewing the NASA Technology Roadmaps recommended the NTR as one of the top 16 technologies that should be pursued by NASA. One of the main issues with developing a NTR for future missions is the ability to economically test the full system on the ground. In the late 1990s, the Sub-surface Active Filtering of Exhaust (SAFE) concept was first proposed by Howe as a method to test NTRs at full power and full duration. The concept relied on firing the NTR into one of the test holes at the Nevada Test Site which had been constructed to test nuclear weapons. In 2011, the cost of testing a NTR and the cost of performing a proof of concept experiment were evaluated.

The Nuclear Thermal Propulsion Stage (NTPS): A Key Space Asset for Human Exploration and Commercial Missions to the Moon

“…Stateof-the-art numerical models are being used to determine reactor core criticality, detailed energy deposition and control rod worth within the reactor subsystem [25,27,35], provide thermal, fluid and stress analysis of reactor fuel elements and core components [36,37], and predict engine operating characteristics and overall mass [38,39]; Task 4. Demonstration of Affordable Ground Testing is focused on maturing equipment requirements and cost estimates for a "proof-of-concept" validation test of the SAFE (Subsurface Active Filtration of Exhaust) [40,41] concept (also known as the "bore-hole" option) at the Nevada Test Site (NTS). Non-nuclear, subscale hot gas injection tests, some with a radioactive tracer gas, would be conducted in a vertical bore-hole to obtain test data on the effectiveness of the porous rock (alluvium) to capture, holdup and filter the engine exhaust.…”