Safe Testing of Nuclear Rockets

Howe, Steven D.; Travis, B. J.; Zerkle, David K.

doi:10.2514/2.5808

Cited by 14 publications

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“…(U,Pu)O 2 solid solutions used for mixed oxide fuel (MOX). Uranium carbides (UC and UC 2 ) are lighter and have higher thermal conductivity than UO 2 and were employed in a composite with graphite as a fuel in a nuclear thermal propulsion experiments, where temperatures of in excess of 3000°C were reached . Uranium carbides are used now in some TRISO‐type fuels.…”

Section: Applications Above 1500°cmentioning

confidence: 99%

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Experimental Approaches to the Thermodynamics of Ceramics Above 1500°C

Ushakov

Navrotsky

2012

J. Am. Ceram. Soc.

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Traditionally, the nuclear and aerospace industries have been the main drivers behind the development of high‐temperature materials. These applications demand a high degree of reliability and extensive characterization of every new material. There is a lack of experimental thermodynamic data above 1500°C even for HfO2, ZrO2, La2O3, Y2O3, and other constituents of widely used ceramic systems. Such data, as are available, were often obtained half a century ago using custom‐built instruments. We review classic experimental approaches for the measurement of formation enthalpies, high‐temperature enthalpy increments by the drop method, and also discuss more recent developments which include mass spectrometric measurements of vapor pressures, pulsed laser relaxation methods for heat capacity, and melting temperature determination and high‐temperature oxide melt solution calorimetry in application to refractory compounds. Approaches to the experimental determination of phase diagrams at high temperature are introduced using studies of liquid immiscibility in the Zr(O)–UO2 system as an example. Thermal analysis above 2000°C is now possible with commercially available instruments, as shown by the first experimental measurements of the phase transition and fusion enthalpies of La2O3. New results on a premelting phase transition in Y2O3 in oxygen are reported from in situ synchrotron X‐ray diffraction study on levitated samples.

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Section: Applications Above 1500°cmentioning

confidence: 99%

“…Uranium carbides are used now in some TRISO‐type fuels. Tri‐carbides and carbonitrides (U,Zr,Nb)(C,N) encapsulated in W(Re) matrix are studied for propulsion . Dissociation of (U,Pu)N at low nitrogen pressures discouraged their further development as a fuel .…”

Section: Applications Above 1500°cmentioning

confidence: 99%

Experimental Approaches to the Thermodynamics of Ceramics Above 1500°C

Ushakov

Navrotsky

2012

J. Am. Ceram. Soc.

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“…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.…”

Section: Task 1 Mission Analysis Engine/stage System Characterizatimentioning

confidence: 99%

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

Borowski

McCurdy²,

Burke

2013

AIAA SPACE 2013 Conference and Exposition

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The nuclear thermal rocket (NTR) has frequently been discussed as a key space asset that can bridge the gap between a sustained human presence on the Moon and the eventual human exploration of Mars. Recently, a human mission to a near Earth asteroid (NEA) has also been included as a "deep space precursor" to an orbital mission of Mars before a landing is attempted. In his "post-Apollo" Integrated Space Program Plan (1970 -1990), Wernher von Braun, proposed a reusable NTPS to deliver cargo and crew to the Moon to establish a lunar base initially before sending human missions to Mars. The NTR was selected because it was a proven technology capable of generating both high thrust and high specific impulse (I sp ~900 s) -twice that of today's best chemical rockets. During the Rover and NERVA programs, twenty rocket reactors were designed, built and successfully ground tested. These tests demonstrated the (1) thrust levels; (2) high fuel temperatures; (3) sustained operation; (4) accumulated lifetime; and (5) restart capability needed for an affordable in-space transportation system. In NASA's Mars Design Reference Architecture (DRA) 5.0 study, the "Copernicus" crewed NTR Mars transfer vehicle used three 25 klb f "Pewee" engines -the smallest and highest performing engine tested in the Rover program. Smaller lunar transfer vehicles -consisting of a NTPS with three ~16.7 klb f "SNRE-class" engines, an in-line propellant tank, plus the payload -can be delivered to LEO using a 70 t to LEO upgraded SLS, and can support reusable cargo delivery and crewed lunar landing missions. The NTPS can play an important role in returning humans to the Moon to stay by providing an affordable in-space transportation system that can allow initial lunar outposts to evolve into settlements capable of supporting commercial activities. Over the next decade collaborative efforts between NASA and private industry could open up new exploration and commercial opportunities for both organizations. With efficient NTP, commercial habitation and crew delivery systems, a "mobile cislunar research station" can transport crews to small NEAs delivered to the E-ML2 point. Also possible are week-long "lunar tourism" missions that can carry passengers into lunar orbit for sightseeing (and plenty of picture taking), then return them to Earth orbit where they would re-enter and land using a small reusable lifting body based on NASA's HL-20 design. Mission descriptions, key vehicle features and operational characteristics are described and presented. NomenclatureE-ML2 = Earth-Moon L2 Lagrange point K = temperature (degrees Kelvin) klb f = thrust (1000's of pounds force) LEO = Low Earth Orbit (= 407 km circular) LOX / LH 2 = Liquid Oxygen / Liquid Hydrogen propellant NERVA = Nuclear Engine for Rocket Vehicle Applications SLS / HLV = Space Launch System / Heavy Lift Vehicle SNRE = Small Nuclear Rocket Engine t = metric ton (1 t = 1000 kg) ΔV = velocity change increment (km/s) ---

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“…Task 4. Demonstration of Affordable Ground Testing focused on "proof-of-concept" validation of the SAFE (Subsurface Active Filtration of Exhaust) [20] or "bore-hole" test option at the Nevada Test Site (NTS). Nonnuclear, subscale hot gas injection tests, some with a radioactive tracer gas, will be conducted in a vertical bore-hole to obtain valuable test data on the effectiveness of the porous rock (alluvium) to capture, holdup and filter the engine exhaust.…”

Section: Notional Plans For Ntp Technology Development and Demonmentioning

confidence: 99%

Near Earth Asteroid Human Mission Possibilities Using Nuclear Thermal Rocket (NTR) Propulsion

Borowski

McCurdy²,

Packard³

2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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The NTR is a proven technology that generates high thrust and has a specific impulse (I sp ~900 s) twice that of today's best chemical rockets. During the Rover and NERVA (Nuclear Engine for Rocket Vehicle Applications) programs, twenty rocket reactors were designed, built and ground tested. These tests demonstrated: (1) a wide range of thrust; (2) high temperature carbide-based nuclear fuel; (3) sustained engine operation; (4) accumulated lifetime; and (5) restart capability-all the requirements needed for a human mission to Mars. Ceramic metal fuel was also evaluated as a backup option. In NASA's recent Mars Design reference Architecture (DRA) 5.0 study, the NTR was selected as the preferred propulsion option because of its proven technology, higher performance, lower launch mass, versatile vehicle design, simple assembly, and growth potential. In contrast to other advanced propulsion options, NTP requires no large technology scale-ups. In fact, the smallest engine tested during the Rover program-the 25 klb f "Pewee" engine is sufficient for a human Mars mission when used in a clustered engine configuration. The "Copernicus" crewed NTR Mars transfer vehicle design developed for DRA 5.0 has significant capability that can enable reusable "1-year" round trip human missions to candidate near Earth asteroids (NEAs) like 1991 JW in 2027, or 2000 SG344 and Apophis in 2028. A robotic precursor mission to 2000 SG344 in late 2023 could provide an attractive Flight Technology Demonstration of a small NTR engine that is scalable to the 25 klb f-class engine used for human missions 5 years later. In addition to the detailed scientific data gathered from on-site inspection, human NEA missions would also provide a valuable "check out" function for key elements of the NTR transfer vehicle (its propulsion module, TransHab and life support systems, etc.) in a "deep space" environment prior to undertaking the longer duration Mars orbital and landing missions that would follow. The initial mass in low Earth orbit required for a mission to Apophis is ~323 t consisting of the NTR propulsion module (~138 t), the integrated saddle truss and LH 2 drop tank assembly (~123 t), and the 6-crew payload element (~62 t). The later includes a multi-mission Space Excursion Vehicle (MMSEV) used for close-up examination and sample gathering. The total burn time and required restarts on the three 25 klb f "Pewee-class" engines operating at I sp ~906 s, are ~76.2 minutes and 4, respectively, well below the 2 hours and 27 restarts demonstrated on the NERVA eXperimental Engine, the NRX-XE. The paper examines the benefits, requirements and characteristics of using NTP for the above NEA missions. The impacts on vehicle design of HLV payload volume and lift capability, crew size, and reusability are also quantified.

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Safe Testing of Nuclear Rockets

Cited by 14 publications

References 0 publications

Experimental Approaches to the Thermodynamics of Ceramics Above 1500°C

Experimental Approaches to the Thermodynamics of Ceramics Above 1500°C

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

Near Earth Asteroid Human Mission Possibilities Using Nuclear Thermal Rocket (NTR) Propulsion

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