Nuclear Thermal, how close is the technology?

[shyningnight]

Relatively new poster, long time Lurker...<br /><br />Been reading posts, and some over at Astronautix.com and edu-ma-cating myself on various launch and propusion technologies.. neat stuff, and it all reminds me that I should have paid more attention in math classes... But that's another story...<br /><br />I got to thinking about Nuclear Thermal propulsion and have a question..<br /><br />GIVEN: Mention the word "Nuclear" and the project is as dead as last weeks mackeral before it even gets started... No reactor of any kind is going to be built in the US or any other place I'm aware of for at least the next 30 years... maybe longer. Whether the hazards are real or imagined is irrelevant.. emotion trumps any reality involved. And of COURSE there ARE real risks and hazards in using nuclear fission to heat a reaction mass... again, put that partly aside...<br /><br />My question is;<br />"How hard would it be, really, given todays technology"?<br /><br />Or, asked another way; "How close could we be if not for the emotional response to the word "Nuclear""?<br /><br />I noticed some "projects" as late as the early 1990's under Nuclear Thermal engines.. and one VERY impressive Russian "design" from 1962-70, the RD-600, with 200,000 kgf and 2000 sec/ISP. Also the "Timberwind" US designs dated "1990".<br /><br />How close were any of them to a "flyable" engine? <br />I know the Nerva program had at least a few test-stand firings, but how far was/is nuclear thermal from something that could lift a useful payload?<br /><br />Curious to read any discussion! (even if it's "hey, you idiot, we just talked about this! ")<br /><br />Paul F.

 

[vogon13]

Saw a show on TLC or Discovery about project Pluto, a nuke powered ram jet. They had footage of a ground test with the reactor at 500 megawatts and zorching an amazing amount of compressed, preheated air for several minutes. Pretty neat (and scary) thing. Nobody was anywhere near it during the test.<br /><br />Orion concept was tested with convential explosives (5 banger IIRC) ~1960. <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[shyningnight]

I recall the "mini" Orion tests with "hockey pucks" of TNT... <br />But you have to admit that Orion would be a little drastic to use in the atmosphere <br />At least with many Nuclear Thermal designs, you're running reaction mass THROUGH a reactor to give it that "oomph" out the back end... not just poppin' atomic bombs under your ship. <br /><br />Paul F.

 

[trigged]

Well, this is a area that really needs to be looked at. The only way to get Isp's AND thrust rates high enough for manned missions to Mars and beyond, is to find a relatively safe way to use Nuclear Thermal/Electric propulsion. Conventional chemical rockets have a relatively low Isp and Ion engines have a very low thrust. Plasma engines would be ideal except for that pesky containment problem. Sometimes we have to reevaluate what we thought was bad in the past and see if it is safe now. <br />Eldon

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>My question is;<br />"How hard would it be, really, given todays technology"?<br /><br />Or, asked another way; "How close could we be if not for the emotional response to the word "Nuclear""?<p><hr /></p></p></blockquote><br /><br />If nobody had a negative feeling about nuclear power and there were no pollution worries or anything like that.....pretty close, really. The main limiting factor will be the fact that for most purposes, the industry is satisfied with what it's got right now and may not be willing to invest in new technology. (Even the aerospike concept, pushed since the 60s and relatively mature for an unflown engine, has been having a heck of a time getting off the ground. Its best shot was VentureStar, unfortunately. Now it has to wait for a new proposed launch vehicle before it can get enough funding to come to fruition.)<br /><br />Technologically, it can be done right now with existing technology. As a total SWAG from somebody with only a layman's understanding of rocket science and very grounding in nuclear science, I'd expect at least fifteen years from project conception to actually flying. This is partly because it's new technology, but mostly because it will need a new launch vehicle to go with it, and that's not an unusual development period for new rockets.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>I noticed some "projects" as late as the early 1990's under Nuclear Thermal engines.. and one VERY impressive Russian "design" from 1962-70, the RD-600, with 200,000 kgf and 2000 sec/ISP. Also the "Timberwind" US designs dated "1990".<br /><br />How close were any of them to a "flyable" engine?<br />I know the Nerva program had at least a few test-stand firings, but how far was/is nuclear thermal from something that could lift a useful payload? <p><hr /></p></p></blockquote><br /><br />Nerva was, I believe, the closest any of them got. There are rumors of Russian designs, but I don't think <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[exoscientist]

Here I discuss a new nuclear propulsion suggestion that might allow a mission to Mars in two weeks:<br /><br />Newsgroups: sci.astro, sci.space.policy, sci.physics <br />From: "Robert Clark" <rgregorycl...@yahoo.com /> <br />Date: 28 Feb 2005 06:54:30 -0800 <br />Local: Mon, Feb 28 2005 6:54 am <br />Subject: About the "Mars in two weeks" nuclear rocket. <br />http://groups-beta.google.com/group/sci.astro/msg/ccb5ebe44a13da71<br /><br /> Bob Clark<br /> <div class="Discussion_UserSignature"> </div>

 

[vogon13]

I have a copy of Nuclear Propulsion for Space, a pamphlet issued by the US Atomic Energy Comission in 1967. A regular goldmine of information:<br /><br />proto- type engines were tested, an engine was tested for 5 minutes in 1959 at 70 megawatts and tempertures of 1777deg. K<br /><br />hydrogen was chosen as the reaction mass<br /><br />Isp doesn't seem to be specified, but that characteristic for a NERVA style engine is described as 'doubled'<br /><br />a test in 1962 reached 1100 megawatts, 2300 deg. K and 55000lbs. of thrust but the engine sustained damage from vibrations from dynamics of reaction mass thru reactor<br /><br />some clever engineering is used to power the pumps to force the reaction mass into the reactor, exhaust is bled from engine to turn turbopumps to drive material into engine<br /><br />they anticipated manned flights to Mars using NERVA type engine on trips lasting 450 days<br /><br />they also projected launching Jupiter probes with flight times of 2 years, and Saturn missions in 3 year flights <br /><br /> Manned Mars craft was expected to weigh 500000 kg and have a crew of 6-8<br /><br />reactor was controlled by turning cylinders around its circumference that either reflected neutrons back into engine or absorbed them as they came out.<br /><br />I don't fully understand this part, but they claim reactor was designed so that varying the amount of reaction mass flowing thru it moderated the neutron balance to change reactor power proportionally, I think the idea is, if you throttle back the reaction mass, the nuclear reaction automatically slows so as not to overheat the reactor<br /><br />lots of exotic materials used in the engine to make it work with out blowing up or melting<br /><br />Quite a well thought out project, and prototype hardware was tested in Nevada desert. Too bad program was cancelled. It would have been grand.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[thalion]

I still think nuclear thermal propulsion is our best bet for high-performance interplanetary travel; even if it could only double the thrust we can obtain with chemical engines, that would be something. Ion drives are efficient, but just too weak to be practical for manned exploration without prodigious energy expenditure (IMO). Solar sails run a close second, with their prospects getting better if we can set them off from inside the Earth's orbit for more solar energy.

 

[shyningnight]

Well it sounds like the Nerva program was a little further along in useable hardware than I thought!<br /><br />I know there are REAL concerns about "accidents" involving nuclear thermal engines... and I'm not saying they would be "simple" to build (it's harder than "we get this here Uranium.. and we stuffs in here like this...")...<br /><br />But the frustrating thing is THIS IS NEARLY 50 YEAR OLD TECHNOLOGY!<br />I have to beleive that a FLYABLE Nuclear Thermal engine, built even with relatively conservative engineering, would be at least 25% more efficient than current chemical rockets using modern materials. Not even "bleeding edge" materials.. but just incrimental improvements over what was tested in Nevada in the early 60's.<br /><br />Oh well.. like I said, I know that anything "Nuclear" is dead on arrival... whether fairly or not.<br /><br />Just think how much simpler plannning for Mars would be with just "that much more" ISP available...<br /><br />Paul F.