Operating Characteristics and Requirements for the NERVA Flight Engine

Altseimer, J.H.; Mader, G. F.; Stewart, J.

doi:10.2514/3.59723

Cited by 25 publications

(6 citation statements)

References 2 publications

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“…The performance parameters of the 10 and 40 kWe point design system concepts include a specific impulse >650 s, thrust from 7-55 N or higher, and a specific power of 11.0 and 21. 9 We/kg at 10 and 40 kWe, respectively. Future emphases on the development of the PeBR concepts should focus on 1) studying the dynamic behavior and stability of the reactor; 2) benchmark experiments to verify the thermal-hydraulics characteristics of the reactor core, fuel pellet design, reactor criticality and safety; 3) feasibility of nonnuclear testing of the fully assembled reactor; and 4) additional engineering analyses of the reactor and its application^).…”

Section: Discussionmentioning

confidence: 98%

Pellet bed reactor concepts for nuclear propulsion applications

El‐Genk

Morley

Pelaccio

et al. 1994

Journal of Propulsion and Power

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Pellet bed reactor (PeBR) concepts have been developed for nuclear thermal and nuclear electric propulsion, and bimodal applications. This annular core, fast spectrum reactor offers many desirable design and safety features. These features include high-power density, small reactor size, full retention of fission products, passive decay heat removal, redundancy in reactor control, negative temperature reactivity feedback, ground testing of the fully assembled reactor using electric heating and non-nuclear fuel elements, and the option of fueling on the launch pad, or fueling and refueling in orbit. In addition to these features, the concepts for nuclear electric propulsion and for bimodal power and thermal propulsion have no single point failure. The average power density in the reactor for nuclear thermal propulsion ranges from 2.2 to 3.3 MW/1 and for a 15-MWe nuclear electric propulsion system the total power system specific mass is about 3.3 kg/kWe. The bimodal-PeBR system concepts offer specific impulse in excess of 650s, tens of Newtons of thrust, and total system specific power ranging from 11 to 21.9 We/kg at the 10-and 40-kWe levels, respectively.

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Section: Discussionmentioning

confidence: 98%

Pellet bed reactor concepts for nuclear propulsion applications

El‐Genk

Morley

Pelaccio

et al. 1994

Journal of Propulsion and Power

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“…The cargo transport's delivery capability to LPO has also been analyzed for a "8-burn" Earth-to-LPO round trip mission reminiscent of that considered previously the establishing the operational characteristics and requirements for the NERVA flight engine [3]. The cargo vehicle again uses a 2-perigee burn departure from LEO and after a 3-day transit captures initially into an elliptical lunar orbit with a perilune of ~100 km and apolune of ~27,700 km.…”

Section: Propulsive Capture Into a 24-hr Eeomentioning

confidence: 99%

“…II. The engines use composite fuel with a U-235 fuel loading of 0.6 g/cm 3 . With a hydrogen exhaust temperature (T ex ) of ~2726 K, chamber pressure of ~450 psia, and a nozzle area expansion ratio of ~300:1, the I sp is ~900 s. The total mission LH 2 propellant loading consists of the usable propellant plus performance reserve, post-burn engine cooldown, and tank-trapped residuals.…”

Section: Mission Payload and Transportation System Ground Rulesmentioning

confidence: 99%

“…The plan envisioned the development of a space shuttle and orbiting space station, along with a reusable NTR propulsion stage that would function as a "workhorse" space asset delivering cargo and crew to the Moon for construction of a lunar base, and then for a human landing on Mars in 1982. The utilization of NTP for lunar mission applications was evident in the fact that the operating characteristics and requirements for the NERVA flight engine were to be based on a non-optimum, eight-burn, crewed mission to lunar polar orbit (LPO) and return [3]. Also considered was a four-burn, reusable cargo delivery mission as well.…”

Section: Introductionmentioning

confidence: 99%

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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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“…They concluded that reactor performance is predominantly limited by the survivability of the fuel at high temperatures. Other limitations of the proposed NERVA system were decay-heat cooling, which required excess propellant and prevented a separate power-generation mode [36].…”

Section: Detailed Studiesmentioning

confidence: 99%

Integrated Propulsion and Power Modeling for Bimodal Nuclear Thermal Rockets

Clough¹,

Starkey²,

Lewis³

et al. 2007

43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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Design point results show that a 316 MWt reactor produces a thrust and specific impulse of 66.6 kN and 917 s, respectively. The same reactor can be run at 73.8 kWt to produce the necessary 16.7 kW electric power with a Brayton cycle generator. This demonstrates the feasibility of BNTR operation with a NERVAderived reactor but also indicates that the reactor control system must be able to operate with precision across a wide power range, and that the transient analysis of reactor decay heat merits future investigation.Results also identify a significant reactor pressure-drop limitation during propulsion and power-generation operation that is caused by poor tie tube thermal conductivity. This leads to the conclusion that, while BNTR operation is possible with a NERVA-derived reactor, doing so requires careful consideration of the Brayton cycle design point and fuel element survivability.

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Operating Characteristics and Requirements for the NERVA Flight Engine

Cited by 25 publications

References 2 publications

Pellet bed reactor concepts for nuclear propulsion applications

Pellet bed reactor concepts for nuclear propulsion applications

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

Integrated Propulsion and Power Modeling for Bimodal Nuclear Thermal Rockets

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