Subscale Design of an NTP Engine Exhaust Containment System

In order for NASA to enable safe manned space flight travel to reach destinations such as Mars, and beyond, advance propulsion technologies, like Nuclear Thermal Propulsion (NTP) will be required. Ground testing for engine qualification will be required as part of the process for novel NTP rocket engines development. Although NTP engines have been tested in the past, methods that were used (open air NTP exhaust) are not acceptable in today's regulatory environment. Currently, there is not an acceptable ground test method that has been successfully operated and safely demonstrated which could scale up to the power levels anticipated from NTP engines currently under consideration. One favorable method is based on a total containment NTP exhaust system concept, which has been documented as a viable option reported by the ARES Corporation on Nuclear Thermal Propulsion Ground Test Facility (2006) concept definition; the total containment option was recommended as one of three possible ground test facility possibilities. There is potential opportunity for Stennis Space Center (SSC) to demonstrate operation of a non-nuclear subscale implementation of the total containment concept for a NTP. This goal of this project is to develop preliminary design elements and integrated systems for making a proof-of-concept technology demonstrator subscale system for a non-nuclear rocket engine. This subscale system would serve as a non-nuclear test bed which could eventually be used to help optimize design, built, and test systems required for operating a safe, environmentally acceptable NTP ground test facility. A total containment NTP exhaust system has been conceptually engineered, however, since this a completely novel approach to address the numerous issues associated with fully containing exhaust from and NTP rocket engine test, to date, no experimental proof-of-concept has been conducted for this innovative technological approach. Therefore, to demonstrate proof-of-concept, this project will develop the preliminary engineering design for a subscale demonstration for a full exhaust containment system. To accomplish this, a closed system of ducts and vessels will be used, and liquid oxygen (LOX) will be injected into the hot hydrogen exhaust to convert it into steam, which will then be condensed and stored as liquid water. Any particulates present, due to sub-optimal engine operation, will either be caught in a particle trap, or end up in water storage vessels, which will store the water indefinitely until fission products either decay, or are filtered, and ultimately can be safely discharged. Gaseous oxygen and any noble gas fission products will then be condensed in a cryogenic heat exchanger and stored in a chilled jacketed Dewar as LOX, and any residual noble gasses, if present, will solidify and can remain stored in the Dewar indefinitely, until the gases have decayed and can safely be released. In this way, all possible fission products that could result from an NTP engine ground test would be captured and stored, and subsequently evaluated and assessed for radioactive contamination and handled accordingly, as needed, over an indefinite period of time. The components for this system will incorporate additional design elements that are currently in development that will be integrated with the overall design concept. Valuable data collected from these separate design components would then feed into the development cycle of a full scale NTP ground test facility based on outcomes of the subscale concept. The subscale technology demonstrator could ultimately serve as a non-nuclear test bed for NTP ground test facility system components and instrumentation, and would prove to be an invaluable resource for use during the design for a full scale NTP ground test facility. The goal of the project is to better prepare and align NASA SSC for successful participation in developing safe, affordable NTP technologies for future manned space flight travel. More »