Can anyone breakdown the cost of developing and implementing an upper stage nuclear thermal engine?

After development, what could the price be of each engine produced?


2 Answers 2


Any sensible answer to your question should make an implicit assumption on the number of engines to be ordered overall. That is, we need to know the number of planned manned flights to Mars and other important destinations, since fixed (sunk) costs of an NTR-based program are significant. The following ideas are based on a few NASA documents discussing NTRs.

Let's see what has to be researched and done today (you can guesstimate person-hours and equipment expenses required, and multiply it by 2.5 to allow for your optimism):

  • Fuel elements together with cladding resistant to the hellish combination of high neutron flux and hot hydrogen
  • A new test rig has to be built at the Nevada test site without making the US look like a violator of test ban treaties
  • Hydrothermoneutronic simulation codes must be re-validated
  • A fueling, test and integration facility should be built at Cape Canaveral
  • A dedicated fuel production facility
  • An engine assembly line
  • NTR control software and hardware
  • The whole suite of vibration, radiation damage, electromagnetic interference, drop, abort etc. etc. tests should be conducted
  • Environmental impact statements should be prepared and filed for all of the above activities and facilities
  • A stringent quality control program must be established bridging the efforts of NASA and DoE.

There are a few concrete sums scattered across the NTRS, but I'd be wary of trusting them blindly. There are also many unknowns, from the number of firings required to the technology to manufacture fuel elements.

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  • (alleged testing of a cermet fuel element under load)
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    $\begingroup$ A related question may be the threshold point for cost-savings over currenbt (LOX/LH2) burnbers of sa given thrust level. $\endgroup$ Jun 19, 2014 at 0:06
  • $\begingroup$ I don't see any problems with the test ban - a NTR is "just" a special kind of nuclear reactor. Project Orion would be different. $\endgroup$ Jun 23, 2014 at 20:19
  • $\begingroup$ @Martin - Apparently, the Russkies considered NERVA a diplomacy problem. $\endgroup$ Jun 27, 2014 at 5:33
  • $\begingroup$ @DeerHunter: Source? Again: Why? $\endgroup$ Jun 27, 2014 at 11:36
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    $\begingroup$ @MartinSchröder txchnologist.com/post/25510667530/… "An account in Annie Jacobsen’s “Area 51: An Uncensored History of America’s Top Secret Military Base,” paints an even wilder picture. On Jan.12, 1965, Jacobsen writes, a Kiwi reactor at Los Alamos was allowed to overheat as a kind of practice drill for a nuclear accident , and eventually burst. A radioactive cloud floated west toward Los Angeles and then out to sea, according to Jacobsen’s book. The Russians argued it violated the Nuclear Test Ban Treaty." $\endgroup$ Jun 27, 2014 at 14:07

In the past 6 years NASA and the DOE have put a fair amount of effort into estimating the cost to recapture NTP technology assuming either graphite based or tungsten CERMET fuel. The estimates to include fuel development, reactor development, reactor testing and infrastructure ranged from $4 to 6 billion over 10 to 15 years.

However, where there has been little thought thus far is in how many engines would be required per decade and how reusable each engine is. The lack of thought is partially due to the fact that the answers would be mission and architecture dependent and as of now there is no mission or architecture.

During the Moon, Mars and beyond program (Constellation) there were some VERY preliminary studies that indicated a decade of lunar exploration could be 40 to 50% cheaper with NTP than chemical engines, but I am not sure at what point you made up the development cost.

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    $\begingroup$ Nice, thanks for answering but could I please bother you to also edit in some references? Like web links to a few most relevant documents and perhaps a citation or two, if the source permits that? Cheers! $\endgroup$
    – TildalWave
    Aug 1, 2014 at 17:23
  • $\begingroup$ That '40-50% cheaper with NTP' figure quoted corresponds with the increase in Isp usually seen in NTR studies. Better performance. The problem is the on-going cost of delivering 'x' mass to destination (?) with an engine/stage costing 'n' dollars. Put another way, is mission cost for NTR actually less than for LO2/LH2? We found out with Shuttle that reusability was not as economical as hoped, though it looked fine on paper. And Shuttle had no radioactive elements. . . $\endgroup$ Aug 1, 2014 at 17:36
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    $\begingroup$ Sadly over the past few years DOE and NASA have been removing many references from OSTI and NTRS. The study I am referring to, regarding system development that I was involved with was completed in the 09-10 timeframe but I cannot find a reference to it on the net. There is this link from the 90's, but I can tell you that it is now outdated. ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19960007720.pdf $\endgroup$
    – Jon
    Aug 2, 2014 at 21:29
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    $\begingroup$ As far as cost per mission, definitely it is cheaper, with regards to usability, there is a political cost as well as a financial one with a system not being reusable. We are trying hard now to get the Iranian's to abandon a highly enriched uranium program, so it is difficult to embark on a program where each mission requires a new batch of HEU. $\endgroup$
    – Jon
    Aug 2, 2014 at 21:31

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