NASA Plans for Particle Bed Nuclear Thermal Flight Demo By 2025

Dr. Jonathan K. Witter is the Chief Engineer for BWXT Advanced Technology Programs. He reviewed the nuclear thermal rocket work from the 1970s to today.

BWX Technologies, Inc. (BWXT) is working with NASA in support of the agency’s Nuclear Thermal Propulsion (NTP) Project. BWXT is responsible for initiating conceptual designs of an NTP reactor in hopes of powering a future manned mission to Mars.

The NTP project seeks to dramatically decrease travel time to and from Mars, while increasing payload size due to a lighter-sized aircraft. Compared to its chemical counterpart, a nuclear thermal rocket possesses twice the propulsion efficiency due to its high-thrust engine and ability to accelerate propellant at high speeds. Given NTP’s advantages over traditional chemical propulsion systems, NASA estimates the technology will reduce transit to the Red Planet from six months to four.

NASA is testing fuel pellets and other components of the system.

China is starting to operate a pebble bed nuclear for commercial power generation at 210 megawatts of electrical power.

NASA is trying to get to nuclear thermal flight demo within 5 years. If all went well they would get a nuclear thermal mission by 2033.

Written By Brian Wang,

36 thoughts on “NASA Plans for Particle Bed Nuclear Thermal Flight Demo By 2025”

  1. If only we could find some better way to shield against neutron radiation. Otherwise, fusion research will have to make nuclear power great again.

  2. Why is proliferation resistance a thing?
    It’s an interplanetary space ship. Are they worried about Martian Muslims or Ceres Communists capturing their ship and making bombs?

  3. He thinks they do their own laundry. Clearly he isn’t in touch with that element of society.

  4. A giant death ray is going to freak people out.

    People get freaked out at the clothing choice of cartoon characters.

    Our best option is to freak them out so hard their heads explode and the rest of us can get on with it.

  5. I don’t agree. Go for the one that is most likely to work, and work quickly.
    Get the screaming and the stupid paper mache puppets out of the way, with real, functioning systems in space as your proof to convince the public.
    THEN you quietly develop the lightbulb, in the background, while you’ve got the first generation operational to give you the financial and political capital to support the research.
    You can introduce the better systems as an “upgrade” that will probably go un-noticed by most. And the screaming opponents have never stopped screaming anyway, just most people have tuned them out.

  6. Good, this is exactly what NASA should be doing. Private companies are starting to take over development of chemical rockets, so it’s time for NASA to be working on more advanced propulsion. Might as well be having your thousands of engineers on staff be doing something useful.

  7. It is the logical next step for large propulsion. If we don’t build it someone else will.

  8. All you guys think it’s a good idea to dump LH2 through TRISO grit and that the primary challenges are political… lol.

    Besides the incredible technical challenges dumping 100kg/s of LH2 through a fluidized bed of sand at 2500K presents, this government (actually the world) shut down because people were dying in nursing homes, and you think this rocket will ever serve? wake up. It’s DOA. it’s tasty pork barrel spending

  9. You’re a lot more optimistic than I am.
    I believe the argument will be made that if the rocket crashes, the fuel will be compacted, cause a China Syndrome, and destroy all life on Earth.
    Congress (being what they are) will argue that the fuel should be flown separately, and start adding restrictions and minimum requirements until they can guarantee you-know-what. We may be able to get around that by buying off Congress (with new facilities in certain districts), but I would expect that to effectively double the cost. And that would just be wetting their beaks.
    I hope it doesn’t happen that way. Once they get started on an industry they will bleed it out while other less friendly space powers establish dominance.
    Being a political cynic is such a drag.

  10. You can get similar result using solar power or beam energy with out the need to freak people out. The important factors are mass and cost. A beam power engine would just be a large light-weight rectenna and simple resistance heating engines. Solar powered could either be solar cells feeding resistance heating engines or a system of mirrors focusing light on a engine.

  11. The lightbulb has been proposed for power production, because it runs at such a very high temperature that in principle very high efficiency should be possible. But the minimum power production would be off the scale for a rocket that wasn’t spending it on propulsion.

  12. Also, I’m kind of amused at the idea that the people who will be founding and populating the first Martian cities somehow need somebody else to give them naming rights.

  13. IMO, I agree if we’re going to do it go with the best systems we can. Not just for efficiency. Not just for the cool factor. The main reason is use it or lose it. We are no longer facing a crippled opponent like the USSR, we’re facing a wealthy and relatively efficient China who definitely will use the most powerful systems they can build. They do not have to worry about public opinion as regards to nuclear activities. If we don’t do it they will, leaving them controlling the high ground and getting there the firstest with the mostest. Public private partnerships seem to have worked well with SpaceX, maybe more of those for nuclear propulsion and general space commercialization and development would be in order.

  14. but, but, but didn’t coronavirus kill the philosophy major’s parents and now they’ve moved upstairs again.

  15. That’s true. But as I say, the political barrier to nuclear propulsion is bad enough that, if you’re going to go through the trouble of busting through it, you might as well go for the gold.

  16. Also the goal of these rockets is usually a bimodal rocket. NTR for thrust and then electricity while coasting. I don’t know if the lightbulb could do that, it seemed to be all about thrust.

  17. It will be fully assembled and fueled when launched. Don’t worry it isn’t particularly radioactive until it is turned on.

    It will be tested in Earth orbit. It will probably fly everywhere (Earth orbit, Lunar orbit, Mars orbit, etc).

    Of course Congress will appropriate funding for commercial launch, by 2025 that is all there will be.

    Of course there will be opposition. That’s all the washed out philosophy majors have to do when they aren’t doing their laundry in their parent’s basement.

  18. Hmmm… it does make one kind of wonder.  

    As all y’all might remember, Tsiolkovsky’s rocket equation accurately predicts much of what is achievable with space comportation.

    | Δv = Isp G₀ logn( Mi / Mo );

    | Mi = initial mass
    | Mo = final mass (obviously, can be ‘midflight’)
    | logn() = natural base ‘e’ log, not log₁₀
    | Isp = specific impulse of the engine
    | G₀ = Earth gravitation constant, 9.80665 N/kg

    Looking at parameters, Isp = 835 is given.  
    There appears to be ejectable inline boosters.  
    So, hard to say ‘Mi’ and ‘Mo’.  

    Still, recalling

    | Ek = ½mv² — kinetic energy
    | F ≈ v⋅dm/dt — and
    | v = G₀ • Isp — so, substituting
    | F ≈ G₀ Isp dm/dt

    And the claim of Isp 835, and force of 25,000 lb then

    | F = 25,000 lb × 0.4536 kg/lb × 9.80665 N/kg
    | F = 111,200 N

    OK, doing a bit more algebra, one finds

    | P₁ > ½ G₀ Isp
    | P₁ > ½ 9.8 × 835
    | P₁ > 4,100 W/N

    Which is the ‘specific minimum power’ to achieve 1 N of force.  

    | P > F P₁
    | P > 111,200 N × 4,100 W/N
    | P > 450,000,000 W

    That’s quite a bit of power. In rocketry terms, not THAT much (you’d be amazed at what the Saturn V’s engines squirted out to get Man to Luna).  

    Still, 500 megawatts of thermal equates to a LOT of neutrons, gammas, nasties.  
    How far from the astronauts must the engines be, not to kill ‘m before the trip is out?

    ⋅-⋅-⋅ Just saying, ⋅-⋅-⋅
    ⋅-=≡ GoatGuy ✓ ≡=-⋅

  19. I don’t know that the nuclear light bulb ever got past the drafting table.

    MITEE seems to draw heavily on Timberwind (and the Rover legacy) all of which actually bent metal and then neutron activated the metal.

  20. J.K.Witter is a great person to work with. His knowledge and enthusiasm are both unmatched.

  21. I have been following this development for some time now, and I have a few questions.
    Will the reactor be lifted fully assembled, or will it be fueled in orbit?
    Will it be tested in Earth orbit or lunar orbit?
    Will Congress appropriate funding for commercial launch?
    I predict opposition.

  22. The government technology development iteration cycle is too long for this to achieve any results before they are overtaken by commercial development. Hire Bezos and Musk to develop it and tell them the prize is the rights to name the first Martian city – ‘Amazon Prime Base’ or ‘Elonograd’. We’ll be vacationing on Mars by the end of the decade.

  23. Why not just go straight to a nuclear lightbulb? It offers 2-3 times the ISP, and even decades ago was considered perfectly feasible.

    If you’re going to do the work to beat back the anti-nuke lunatics, you might as well make it worth it.

  24. What’s the difference between China and your Willy?

    China didn’t issue a growth target for this year.

  25. Project Timberwind/SNTP rides again!

    “Initially, PIPET [Particle Bed Reactor Integral Performance Element
    Tester] was envisioned as a small, low-cost, SNTP-specific experiment
    for testing and qualifying PBR fuel and fuel elements. The demands by
    other agencies, DOE and NASA, resulted in a national test facility for
    NTP fuel, fuel elements, and engines. Its size out grew the SNTP
    Program’s ability to secure the funds for such a large construction
    project. Though the demands were placed upon the SNTP Program to expand
    the facility’s scope and the SNTP Program’s management tried to
    coordinate tri-agency, DoD-DOE-NASA, support and funding, adequate
    funding support for the national ground test facility was not obtained.”


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