Talk:Nuclear thermal rocket/Archive 1

Untitled
How about the other designs? Gaseous core designs have neen proposed, I think. I just don't have enought information to include in a decent article section... but this info is lacking.


 * There's a stubby article on it at Gaseous fission reactor. I'll put a link to it into this article. Bryan 01:01, 3 Jun 2004 (UTC)

Picture
Can someone please explain to me (or preferably to everyone by adding to the article) just what the heck is happening in this picture? The caption in the article and the one on the nasa site are really unhelpful. Am I truly looking at a runaway criticality/excursion and explosion of a nuclear reactor core here or what?! If so this must've released a massive amount of radionuclides into the atmosphere and surrounding landside. If so, why is there apparently no other information on this event...yeild of excursion, fallout, cleanup(if any??)?--Deglr6328 05:45, 13 Oct 2004 (UTC)


 * I'm not an expert but I feel quite confident in saying that's not a nuclear explosion, nuclear reactors don't go critical in the way bombs do. My guess would be that they simply cranked up the power output until the reactor melted or burst from the pressure of the heated propellent, after which the reactor would have stopped working. Bryan 06:02, 13 Oct 2004 (UTC)

Pu releases
"Three to five tons of plutonium (about 320,000 curies) were released into the atmosphere by weapons testing from the end of WWII (1945) until the Partial Test Ban Treaty was signed in 1963. No deaths have been detected from this, even though anti–nuclear organizations state that one gram (1/28 of an ounce) of plutonium is enough to give everyone on Earth cancer." What is this non sequitur? 3 to 5 tons of Pu, seems it should say something like 300,000 - 500,000 curies, or what ever it should be. The point is if the mass is a range, so should be the amount of radioactivity. How do we know this figure? Then, is it just Pu? Some of those are U explosions. And every nuclear explosions produces some of EVERY nuclide. Then if there were/are some excess deaths/cancers from this added radioactivity, how could it be reliably associated with the addition to the background? But just because it is hard to pin down doesn't mean it isn't happenning. An then the sentence continues with a claim that someone said, as if that were the only thing people have to say. So how much Pu WOULD it take to give everyone cancer? Properly applied, not much. Small breathed in particles. But that's not the point. That's like asking how much water would it take to drown everyone on earth. About a bucket, if we all take turns. Ie sounds editorial to me. As far as cancer goes, those atmospheric tests cause uneven distribution. People nearby got a lot more than further away. .. So just averaging out 5 tons over the whole atmosphere is very misleading. Like I said in edit now commented out, Cancer accounts for half the deaths of advanced societies. Seems to be problem. Comments? 67.118.117.2 03:32, 3 Nov 2004 (UTC)

"Between 1963 and 1980 the U.S. exploded 316 nuclear devices underground. The radioactivity from these is already equivalent to the nuclear waste from many nuclear reactors." Request for clarification. Does this mean the r.a. released into the atmosphere is == to r.a. released into atmosphere from nuclear waste ? Or does it mean r.a. waste, or what? 67.118.117.2 03:38, 3 Nov 2004 (UTC)


 * These passages have been added twice now, and I have twice removed them. For one, these engines do not use Pu, so any comment on Pu release is obviously of limited use. Furthermore, the editor made no attempt to compare these releases with the amount of uranium in these engines (which is likely difficult to find anyway) so it really doesn't help anything. Maury 16:29, 23 May 2006 (UTC)


 * They have been added, and removed, again. The IP of the anon user in question ends up at Lockheed Martin, which seems ironic. Maury 01:06, 29 June 2006 (UTC)

Nuclear weapons are (emphatically) not the same as nuclear rockets. Nuclear rockets can and should, theoretically, release zero radioactive materials. Voronwae (talk) 07:00, 7 February 2010 (UTC)

Thrust-to-weight
The statement that a solid-core reactor cannot have a T/W >1 only applies to NERVA. The designers weren't trying hard for high thrust because they didn't expect to use it as a booster. DUMBO (mentioned lower on the page!) had a higher thrust. A particle-bed reactor, as designed in the Timberwind program, wouldn't have only had a T/W slightly greater than 1. I don't know if the design was realistic, but Timberwind was supposed to have had a T/W of 30, enabling it to propel a launch vehicle. SpaceCaptain 02:44, 30 September 2005 (UTC)

LOX as propellant
Just a curious observation, nuclear thermal has a lot going for it, but no one ever considered using lunar LOX as a propellant mass instead of H2. Other than the annoying reactive properties of oxygen, there would be little difference as a propellant. But, oxygen could be readily extracted from regolith on the moon, creating a limitless supply of propellant mass to reach the outer solar system. Launch masses for trips to other planets could be cut in half.

Actually, it has been considered. LOX offers a much lower exhaust velocity than LH2, but higher density and greater stability in storage (it doesn't boil off). And, of course, it's available on the Moon. SpaceCaptain 18:26, 22 December 2005 (UTC)

Calculations in § Nuclear vs Chemical
In th following step :
 * Finally, one must consider the design of the stage as a whole. The S-IVB carried just over 300,000 litres of fuel, 229,000 litres of liquid hydrogen (17300 Kg), and 72,700 litres of liquid oxygen (86 600 Kg). The S-IVB uses a common bulkhead between the tanks, so removing it to produce a single larger tank would increase the total load only slightly, for argument's sake, perhaps 2,000 litres. Assuming this for the moment, this means the new hydrogen-only nuclear stage would carry about 231,000 litres in total (231 m³), or about 16,500 kg (36,350 lb). At 1,725 litres per second, this is a burn time of only 135 seconds, compared to about 500 in the original S-IBV (although some of this is at a lower power setting).

Why is the new capacity 229,000+2,000 ? It should be as said a single larger tank of 303,700 l

With this volume, burn time is about 170 s and delta-V 6600 m/s. These values don't compromise the subsequent argumentations. Duckysmokton 14:38, 30 November 2006 (UTC)


 * I think I'm missing something, 229000 + 2000 = 231000? Maury 13:12, 6 December 2006 (UTC)
 * Ohh, duh. Please, feel free to fix my error! Maury 13:18, 6 December 2006 (UTC)

Exhaust radioactivity?
There is no information in the article on radioactivity of the exhaust. Since hydrogen passes through the reactor core, shouldn't it be affected somehow? Are the effects negligible? Does anyone know? Educated guesses? 67.188.208.211 (talk) 22:52, 13 July 2008 (UTC)


 * There might be some tritium produced, but probably not a lot. There's unlikely to be significant radioactivity in the exhaust provided there's no major structural failures of the reactor core.- (User) WolfKeeper (Talk) 23:31, 13 July 2008 (UTC)

The hydrogen itself is mostly not affected at all other than being heated. A little tritium might be produced as the result of neutron bombardment. Depending on the firing duration, small amounts of gaseous fission byproducts may swell the fuel and exit in the exhaust. Voronwae (talk) 19:43, 19 March 2010 (UTC)

the article states that the reactor lost 38 pounds of fuel in 2 hours of running, thats a significant amount of radiation, even assuming it's all enriched uranium. More likely it's whatever radionuclides a 4000 MW fission reactor produces, most of which would boil off before uranium oxide and graphite would. Tritium production should be negligable, given that any given hydrogen atom would have to capture 2 neutrons during it's very short stay inside the reactor.70.79.195.123 (talk) 23:05, 14 May 2010 (UTC)

This is the main difference between "open cycle" and "closed cycle" designs. In the former, the rocket fuel is run directly over the nuclear elements, some of which escape with the fuel (though this gives better performance than closed cycle). In the latter, the rocket fuel never directly touches the nuclear elements, so there is no release of radioactive material (at the cost of lower performance than open cycle). Winged Cat (talk) 16:34, 25 October 2020 (UTC)

Zirconium
Where Zirconium hydride is mentioned in the article I think zirconium carbide is the compound used.

Not certain, so didn't fix. Anyone who can comment or fix please do. Keith Henson (talk) 20:45, 22 June 2012 (UTC)

Risks
While I wish it was true, this statement is incorrect: "The U.S. Rover program did in fact purposely destroy a Kiwi reactor to simulate a fall from altitude, and no radioactive material was released."

That is statement refers to the January, 1965, KIWI-TNT test: The results included (sourced, in-line):
 * Within a 7620 m (25000 ft) radius, only about 50% of the core material could be accounted for. The remainder presumably either burned in the air or was so fine as to be carried further downwind in the cloud;
 * It was estimated on the basis of the total energy which was produced by the excursion that only 5-15% of the core could have been vaporized; {Finseth, J. L., "Overview of Rover Engine Tests-- Final Report," NASA, 1991, p. 63)
 * Personnel hazards are summarized as follows:
 * Out to approximately 300 ft, almost all radiation exposures would be fatal, being in excess of 1,000 rads.
 * Between approximately 300 and 600 ft varying degrees of radiation injury including some fatalities, would occur as exposure would be between 200 and 1,000 rads.
 * Between approximately 600 and 750 ft exposures would be tween 100 and 200 rad producing slight illness.
 * From 750 to 1,200 ft, exposures would range from 25 to 100 rad, producing some very slight hematological change, but no illness.
 * Beyond 1,200 ft, out to approximately 2,000 ft, there would be little, if any, injury or clinical effects, but exposure would exceed approximately 3 rads and would require administrative investigation and reporting.
 * Beyond 2,000 ft there would be no hazard. (Fultyn, R. V., "Environmental Effects of the Kiwi-TNT Effluent: A Review," Los Alamos, 1968, p. 35.)
 * Within a few hours of the test contamination above 1 mR/hr was difficult to find beyond 2 miles, although a few "hot spots" of several mR/hr were discovered out to 10 miles on the day of the test. These rapidly decayed away to insignificance.  Beyond 12 miles, no contamination above 1 mR/hr was found. (Fultyn, p. 65.)

-- cregil  (talk)  01:37, 27 June 2012 (UTC)

Recent Edits
"(→‎Kiwi-TNT: cut down the damage lists by a huge amount, way too long.)"

On a start class article?

I am more than a little uncomfortable with "way too long" and "huge amount" (2200 characters) as criteria for unilateral deletion -- especially without discussion.

Fine. So be it.

Someone, other than me (now), needs to:
 * make use of the Final Report (it is linked at the bottom of the article) to fill in this anemic article.
 * include information on the upcoming ISS test of the VASIMR, and
 * include information regarding the recommendation by NASA's Design Reference Architecture of 2009.

I have all of that information, read, digested, and ready to go before me to include in this article, but since I encountered attitude instead of cooperation, then:

You do it.

For future reference, we are working on an article, not a pamphlet; and it expected that one will assume that other editors are part of that "we" and, further, that they are working in good faith.

-- cregil  (talk)  19:53, 27 June 2012 (UTC)
 * I'm not sure start class is accurate. I didn't see the need for us to have 2200 characters on a single test describing the radiation levels every couple of hundred feet so I summarized it. All the other tests we described in a paragraph (or less) so I chopped KIwi-TNT to a similar size. - SimonLyall (talk) 23:29, 27 June 2012 (UTC)

Radioactive Risk Reduction
It might be better to give a more detailed overview over the risks. Why is there for example no mention of how much radioactive material, that would be released into the atmosphere? How much is used in the NTR anyways? --92.225.93.242 (talk) 02:05, 6 August 2012 (UTC)


 * NTRs are to be engineered as second stage rockets, not used in the atmosphere of the Earth. And even once in space there should be no radioactive residue. If you take the time to read the article, much like a reactor aboard a naval vessel, the reactor is contained and used for heating, in this case a propellent like hydrogen. I cannot stress enough that there is no radioactive exhaust! The only possible radioactive contamination that could be released on the Earth would be during a launch accident. The risk can never be zero. Unfortunately, isotopes have been released into the atmosphere in the past from some space launches, including from NASA, that ended in accidental explosion. Doyna Yar (talk) 04:19, 14 January 2013 (UTC)

DUFF
http://www.nasa.gov/centers/glenn/news/pressrel/2012/12-059_fission_prt.htm

— Preceding unsigned comment added by Crews Giles (talk • contribs) 21:34, 4 December 2012 (UTC)

Chemical vs Nuclear Section
This section needs a conclusion or explanation that is understandable by laymen. As it stands, it is completely useless unless one is a science major who understands the math. This is an encyclopaedia not a science book. Average people need to be able to understand what is being said even if in summary. Theshowmecanuck (talk) 03:51, 14 January 2013 (UTC)


 * in short the thinking is a NTR could be developed for beyond Earth orbit that could be twice as efficient as a chemical rocket engine. I added a line or so clarifying, though I'll probably have to follow up with a citation. Joy- more work. Doyna Yar (talk) 04:35, 14 January 2013 (UTC)

Hydrogen?
Why using Hydrogen as propellant? All the energy is coming from the nuclear reaction. So, the propellant only has to provide mass to be accelerated. Hydrogen being very light would be a very bad propellant in this case. Why not using simple Water? It has a higher density than Hydrogen and therefore would use up much lesser space. — Preceding unsigned comment added by 178.9.155.196 (talk) 11:40, 5 May 2014 (UTC)

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Future SpaceX nuclear-thermal rocket?
https://www.nextbigfuture.com/2018/07/x-spacex-raptor-designer-has-ready-for-development-designs-for-nuclear-rocket-that-will-be-2-7-times-better-than-bfr.html

https://drive.google.com/file/d/11WcdsIT3RX_3idEBYouKFdWVjb8PybFb/view

Might be worth mentioning under current research. I leave it to others to decide whether this merits inclusion on the strengths of the links above. — Preceding unsigned comment added by 62.64.229.95 (talk) 09:06, 10 July 2018 (UTC)

"citation needed" tags
Many "citation needed" tags actually seem to be "explain it like I'm 5" tags?:)--Bstard12 (talk) 00:40, 7 July 2020 (UTC)