Record Details

Affordable Development and Demonstration of a Small NTR Engine and Stage: How Small is Big Enough?
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Author and Affiliation:
Borowski, Stanley K.(NASA Glenn Research Center, Cleveland, OH United States);
Sefcik, Robert J.(NASA Glenn Research Center, Cleveland, OH United States);
Fittje, James E.(Vantage Partners, LLC, Brook Park, OH, United States);
McCurdy, David R.(Vantage Partners, LLC, Brook Park, OH, United States);
Qualls, Arthur L.(Oak Ridge National Lab., TN, United States);
Schnitzler, Bruce G.(Oak Ridge National Lab., TN, United States);
Werner, James E.(Idaho National Lab., Idaho Falls, ID, United States);
Weitzberg (Abraham)(DOE Consultant, Woodland Hills, CA, United States);
Joyner, Claude R.(Aerojet Rocketdyne, Inc., West Palm Beach, FL, )
Abstract: The Nuclear Thermal Rocket (NTR) derives its energy from fission of uranium-235 atoms contained within fuel elements that comprise the engine's reactor core. It generates high thrust and has a specific impulse potential of approximately 900 seconds - a 100% increase over today's best chemical rockets. The Nuclear Thermal Propulsion (NTP) project, funded by NASA's AES program, includes five key task activities: (1) Recapture, demonstration, and validation of heritage graphite composite (GC) fuel (selected as the "Lead Fuel" option); (2) Engine Conceptual Design; (3) Operating Requirements Definition; (4) Identification of Affordable Options for Ground Testing; and (5) Formulation of an Affordable Development Strategy. During FY'14, a preliminary DDT&E plan and schedule for NTP development was outlined by GRC, DOE and industry that involved significant system-level demonstration projects that included GTD tests at the NNSS, followed by a FTD mission. To reduce cost for the GTD tests and FTD mission, small NTR engines, in either the 7.5 or 16.5 klbf thrust class, were considered. Both engine options used GC fuel and a "common" fuel element (FE) design. The small approximately 7.5 klbf "criticality-limited" engine produces approximately 157 megawatts of thermal power (MWt) and its core is configured with parallel rows of hexagonal-shaped FEs and tie tubes (TTs) with a FE to TT ratio of approximately 1:1. The larger approximately 16.5 klbf Small Nuclear Rocket Engine (SNRE), developed by LANL at the end of the Rover program, produces approximately 367 MWt and has a FE to TT ratio of approximately 2:1. Although both engines use a common 35 inch (approximately 89 cm) long FE, the SNRE's larger diameter core contains approximately 300 more FEs needed to produce an additional 210 MWt of power. To reduce the cost of the FTD mission, a simple "1-burn" lunar flyby mission was considered to reduce the LH2 propellant loading, the stage size and complexity. Use of existing and flight proven liquid rocket and stage hardware (e.g., from the RL10B-2 engine and Delta Cryogenic Second Stage) was also maximized to further aid affordability. This paper examines the pros and cons of using these two small engine options, including their potential to support future human exploration missions to the Moon, near Earth asteroids, and Mars, and recommends a preferred size. It also provides a preliminary assessment of the key activities, development options, and schedule required to affordably build, ground test and fly a small NTR engine and stage within a 10-year timeframe.
Publication Date: Sep 01, 2015
Document ID:
20150023036
(Acquired Dec 17, 2015)
Subject Category: SPACECRAFT PROPULSION AND POWER; SPACECRAFT DESIGN, TESTING AND PERFORMANCE
Report/Patent Number: AIAA Paper 2015-4524, GRC-E-DAA-TN25913
Document Type: Conference Paper
Publication Information: (SEE 20150021287)
Meeting Information: Space 2015; 31 Aug. - 2 Sep. 2015; Pasadena, CA; United States
Meeting Sponsor: American Inst. of Aeronautics and Astronautics; Reston, VA, United States
Contract/Grant/Task Num: NNC12BA01B; WBS 279585.10.99.99.99.22
Financial Sponsor: NASA Glenn Research Center; Cleveland, OH United States
Organization Source: NASA Glenn Research Center; Cleveland, OH United States
Description: 29p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright; Distribution as joint owner in the copyright
NASA Terms: CERAMIC NUCLEAR FUELS; NUCLEAR PROPULSION; ENGINE DESIGN; FLIGHT TESTS; GROUND TESTS; METAL PROPELLANTS; MISSION PLANNING; FABRICATION; GRAPHITE; SCHEDULES; COST REDUCTION
Other Descriptors: SPACECRAFT DESIGN; NUCLEAR ROCKET ENGINES; LUNAR FLYBY MISSION
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