Phoenix9
Topic Author
Posts: 2024
Joined: Tue Aug 28, 2007 8:25 pm

Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 4:47 am

Hello all!

This has been going on in my mind for a while...so just wanted to get your opinion on this:

Why can't we have nuclear powered aircraft while nuclear power has been used in ships, submarines etc.? Can't we have a "mini" reactor on a plane that can generate the energy required to power the turbines?

I know there are a lot of potential dangers but there are also potential benefits (obviously with strict safeguards in place). With fossil fuels running low with increasing costs...wouldn't it be easier to power the future airliners with nuclear power??
Life only makes sense when you look at it backwards.
 
User avatar
Moose135
Posts: 3086
Joined: Mon Oct 04, 2004 11:27 pm

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 4:58 am

I'm not sure just how one would work. Years ago, my one of my aero professors talked about studying nuclear powered aircraft back in the late 50s or early 60s, and while the technology is much different today, it wasn't something that was feasible. For one thing, the weight of the reactor, along with the necessary shielding would be excessive for an aircraft. Also, I don't know how you would actually use a nuclear reactor for propulsion in an aircraft. In a ship, the reactor is used to create steam, which runs a turbine to turn the ship's propeller. That wouldn't really translate into an aircraft application. And of course, even with strict safeguards, you have the problem of flying all these operating nuclear reactors around the sky, in all sorts of weather, in and out of major cities around the world. I know that isn't going to happen any time soon!
KC-135 - Passing gas and taking names!
 
YYZatcboy
Posts: 1183
Joined: Fri Apr 22, 2005 2:15 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 5:02 am

plus it takes at least two people to run a reactor, which means having a crew of 4 on the flight deck.
DH1/3/4 MD11/88 L1011 A319/20/21/30/50/80 717 727 735/6/7/8/9 744 762/3 77E/W 788/789 E40/75/90 CRJ/700/705 CC150
J/S DH8D 736/7/8 763
 
kaitak744
Posts: 2209
Joined: Fri Jul 22, 2005 1:32 pm

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 5:25 am

This was tried on a B-36 a long time ago. As said above, a nuclear reactor can only power a propeller aircraft. The energy of a reactor can not effectively be translated into a turbofan.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 5:42 am

Quoting Phoenix9 (Thread starter):
Why can't we have nuclear powered aircraft while nuclear power has been used in ships, submarines etc.? Can't we have a "mini" reactor on a plane that can generate the energy required to power the turbines?

It can, and has, been done on a military prototype. The safety and political issues make it a non-starter for either military or commercial.

Quoting Kaitak744 (Reply 3):
As said above, a nuclear reactor can only power a propeller aircraft. The energy of a reactor can not effectively be translated into a turbofan.

Why not? A propeller is just a slow spinning fan. Given that a nuke would decouple the turbine and the fan, it's just a matter of gearing.

Tom.
 
rfields5421
Posts: 5940
Joined: Thu Jul 19, 2007 12:45 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 6:20 am

A nuclear reactor is a boiler used to create steam.

You would not have nuclear reactor powered aircraft - you would have a steam engined aircraft.

Now just think hard about what it would take to create a system with 800 psi or 1200 psi or 1600 psi steam - how fast the prop would have to turn and how much gearing would be required.

Then you need two water systems for the reactor - the radioactive side with it's cooling system and the head exchanger and the clean water used to power the turbines.

Quoting Tdscanuck (Reply 4):
Given that a nuke would decouple the turbine and the fan, it's just a matter of gearing.

A ducted fan - yes a nuke could power it.

A thrust generating jet engine relies on the expansion of the gas/air during combustion to produce thrust.

Spinning the fan isn't going to generate enough thrust.

I think the issue with nuclear power as we know it today is and always will be weight.

To engineer such a boiler, steam and cooling system so that it cannot break open and leak in a crash would require way too much weight.
 
chiad
Posts: 1282
Joined: Tue May 16, 2006 4:24 pm

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 8:36 am

This might be a little off topic, but considering the future I believe we will see Helium-3 (as a part of nuclear fusion) powered Aircrafts.
Actually I believe we will see Helium-3 powering all vehicles.
Helium-3 will come delivered with the, lets say, B898 or A470 as a part of the aircraft that would only be changed during a major maintenance work.
Or an new aircraft will come with the specifications that it will be able to run for 20 years.

Helium-3 is estimated 40 years into the future (a little late for global warming), but when we are able to extract and transport it (from the moon) properly it will change everything.

Enormous amounts of energy, no pollution, just pure love!  Silly

It's kind of technical, but you can read more about it here (or just Google it):
http://en.wikipedia.org/wiki/Helium-3
 
User avatar
ADent
Posts: 1050
Joined: Fri Dec 22, 2006 12:11 pm

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 8:44 am

No nuclear aircraft - due to weight (and some other reasons listed above).

But you could have hydrogen powered aircraft with the nuclear reactor at the airport generating the hydrogen.
 
AA7295
Posts: 461
Joined: Fri Aug 03, 2007 8:19 pm

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 8:47 am

Can you imagine the terrorism risk? Even if they were shot down from the sky, or blown up mid air.

Consider how safely guarded nuclear powerplants are and then imagine having a flying nuclear power plant. I don't see it ever happening unless there is some magical technology that can immediately mitigate the blast of a nuclear weapon.

Regards,
AA7295
 
PADSpot
Posts: 1637
Joined: Sat Jan 15, 2005 11:31 pm

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 8:49 am

Quoting Phoenix9 (Thread starter):
Why can't we have nuclear powered aircraft while nuclear power has been used in ships, submarines etc.? Can't we have a "mini" reactor on a plane that can generate the energy required to power the turbines?

Because different to ground- or water-based means of transport weight matters and a nuclear reactor that generates enough power to replace two GE-90 for instance could easily weigh 100tonnes
 
rtfm
Posts: 421
Joined: Sat Oct 09, 2004 5:35 pm

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 9:22 am

Quoting Tdscanuck (Reply 4):
It can, and has, been done on a military prototype.

The reactor that was carried on the B36 never actually powered the a/c as far as I am aware. More info on Wikipedia here:

http://en.wikipedia.org/wiki/B36#Experiments

I don't think that there has ever been an a/c powered by a nuclear power plant....
 
helvknight
Posts: 784
Joined: Fri Aug 04, 2006 10:35 pm

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 9:59 am

Quoting RFields5421 (Reply 5):
I think the issue with nuclear power as we know it today is and always will be weight.

To engineer such a boiler, steam and cooling system so that it cannot break open and leak in a crash would require way too much weight.

In addition the reactor would need to be shielded, a land based plant uses a concrete structure inside a steel containment vessel, all in a heavy concrete shell. Obviously marine systems aren't quite as rugged but there is still a lot of shielding to prevent release of radiation.

also the control system (boron rods) and the rest of the plant will all add weight.

You could probably build one but I don't think it would get off the ground with a viable payload.

Finally when it comes to the end of its service life (maybe 20,000 cycles) how do you recycle it?
I refuse to join any club that would have me as a member - Groucho Marx
 
sparkingwave
Posts: 568
Joined: Thu Jun 09, 2005 1:01 pm

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 10:34 am

There have been nuclear-powered jet engines...!

Research was undertaken on a nuclear-powered bomber in the United States back in 1955. There was a design competition which was won by Lockheed with the 125A weapons system, with the requirement for a supersonic, high-altitude plane.

General Electric, and Pratt & Whitney proposed their own nuclear jet engine designs. GE came up with the "direct cycle" engine, but it had limited thrust and spewed radioactivity directly into the atmosphere. P&W's 'indirect cycle' engine could propel a plane to supersonic speeds, but the engineering problems were too great to overcome.

GE made a prototype of its X39 direct cycle turbojet engine, but its results were disappointing - it only produced 10% of the thrust needed to lift a plane off the ground. P&W's design never made it past the engineering stage.

With these setback, the government scaled back its requirements, hoping to try to make a subsonic, "continuously airborne missile-launcher and low-level weapons system", known by the acronym CAMAL. Convair won out on the design with its NX-2 model bomber design in 1960. But in 1961, President Kennedy canceled all government support for nuclear jet propulsion and related bombers.
Flights to the moon and all major space stations. At Pan Am, the sky is no longer the limit!
 
cobra27
Posts: 939
Joined: Wed May 23, 2001 6:57 pm

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 10:48 am

In big oceangoing ships maybe (already done in the past), not particulllary succesful because of high cost.

But in planes, not really. on the other side it would really be attractive, almost unlimited range atc...
 
baroque
Posts: 12302
Joined: Thu Apr 27, 2006 2:15 pm

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 12:26 pm

Quoting Chiad (Reply 6):
Enormous amounts of energy, no pollution, just pure love! Silly

Welcome to the concepts of the 1950s and we know how they turned out.

Quoting ADent (Reply 7):
No nuclear aircraft - due to weight (and some other reasons listed above).

They would make the A380 look like a very model of structural efficiency. You would not need to vent the steam, in fact that would ensure the system it would be very short ranged, but you could make a really all electric engine. Still far too heavy, but the amount of water would be limited. Where is Connies4?
 
PADSpot
Posts: 1637
Joined: Sat Jan 15, 2005 11:31 pm

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 12:34 pm

In case I am allowed to make a projection, the most likely case today is that when conventional, petroleum-based jet fuel is no longer a viable source of energy then Hydrogen will become the next jet fuel. It's supply is basically unlimited, it's clean and it can be used in slightly adapted gas turbines as they used today. The major problem being its storage on the airplane.
 
OPNLguy
Posts: 11191
Joined: Tue Jun 15, 1999 11:29 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 12:42 pm

Another reason is, quite simply, is that aircraft crash. Irrespective of whether it's from pilot error, weather issues, or mechanical issues, aircraft crash, and when they do, there is usually great fragmentation of the wreckage due to the high speeds/forces involved which would likely compromise a reactor and spread radioactive materials across countryside not to mention the crash site.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
FlySSC
Posts: 5325
Joined: Tue Aug 12, 2003 1:38 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 1:03 pm

Quoting Moose135 (Reply 1):
Years ago, my one of my aero professors talked about studying nuclear powered aircraft back in the late 50s or early 60s

In the 50s, One of the projects of Lucien Servanty, the "father" of Concorde, was to build what was called the "Super Caravelle" and aircraft powered by a nuclear "battery"

Here are some pictures of the projects :

http://farm2.static.flickr.com/1296/1323448157_164a2262e4_b.jpg
 
jamincan
Posts: 573
Joined: Mon Aug 21, 2006 9:28 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 1:43 pm

Quoting PADSpot (Reply 15):
In case I am allowed to make a projection, the most likely case today is that when conventional, petroleum-based jet fuel is no longer a viable source of energy then Hydrogen will become the next jet fuel. It's supply is basically unlimited, it's clean and it can be used in slightly adapted gas turbines as they used today. The major problem being its storage on the airplane.

It would be interesting to investigate that further. I imagine that the storage problems could be overcome - possibly storing it as a less volatile compound and then releasing the hydrogen through some sort of chemical reaction.

I would also be curious how much more environmentally friendly a hydrogen-powered jet would be vs. one powered with regular jet fuel. The emissions would certainly be clean; however, water vapour is a greenhouse gas, so it's benefits with respect to climate change may not be as great as it seems on the surface.
 
ltbewr
Posts: 14572
Joined: Thu Jan 29, 2004 1:24 pm

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 2:04 pm

Three other factors against Nuke powered aircraft besides the weigh penalty: 1) Especially in the USA and parts of Europe, they would be afraid fly such an powered a/c due to deep fears of nuclear power plants (Three Mile Island, Chernobyl), 2) It would be uninsurable, no private company would ever write a policy on such powered a/c and 3) many countries would ban it from flying over their countries.
 
102IAHexpress
Posts: 927
Joined: Sat Feb 19, 2005 6:33 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 2:41 pm

I think the theory 50 years ago by the US Air Force was that there would be big advantage in having an aircraft that could stay in the air for weeks at a time. And they developed an aircraft that could do just that. But, the problem was not so much the weight, but rather the inadequate shielding on the aircraft. The crew’s exposure to radiation limited the length of time the aircraft could stay in the air, thus limited the usefulness of the aircraft.

The big advantage of such an aircraft today would be the fuel savings. I don’t have the numbers but the US Air Force spends a lot of money on fuel. I wonder if any of the military guys can share some insight on whether a blended wing designed aircraft could adequately support and shield the nuclear reactor.
 
User avatar
Stitch
Posts: 26728
Joined: Wed Jul 06, 2005 4:26 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 2:51 pm

Both SparklingWave and 102IAHexpress sum it up pretty well.

The USA W(eapons)S(ystem)-125A program was to develop a nuclear-powered bomber capable of long-term loitering to protect the asset against a surprise Soviet attack on US bomber bases. At the time it was developed, ICBMs were in their infancy and SLBMs did not exist, so heavy bombers were the only leg of the "Strategic Triad". Both GE and P&W worked to develop nuclear-powered engines which used the nuclear pile instead of burning kerosene to heat air to provide thrust, but none of the designs were feasible.

In addition to WS-125A, there was a simultaneous program - WS-110 - to develop a conventionally-powered high speed bomber which became the XB-70.

There was an amazing thread in TechOps about the XB-70 program, which touched a bit on the WS-125 as well: B-70: Was There Ever A Serious Mach 4 Requirement? (by Starglider Feb 12 2007 in Tech Ops)
 
Norlander
Posts: 138
Joined: Sat Sep 22, 2007 10:39 pm

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 3:22 pm

I think that the next propulsion revolution in aircraft propulsion is quite far away. Biofuels will become more efficient (using ocean surfaces, selected breeding and genetic modifications) and will be refined into Jet-A grade as time goes by, keeping in place the commodity system established by the fossil fuels. But when energy-cells become more cost and weight efficient to use they will replace it, and you'll have aircraft loaded with "batteries" of energy. The actually energy production will then solely be at power plants, powered by wind/water/solar/bio/fission/fusion sources.
Longtime Lurker
 
Carls
Posts: 194
Joined: Thu Aug 16, 2007 1:22 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 4:20 pm

Nuclear powered aircraft won't be allowed to fly over USA soil.
I don not know all the restrictions that EU and China could have, but I think will be hard, really hard.
Too much risk for everybody.
 
SMcC
Posts: 37
Joined: Sun Sep 24, 2000 8:57 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 4:38 pm

Risk...?
Nah There will eventually be some revolutionary developements in nuclear technology that will not only make it very safe and environmentally friendly, but also applied widespread across industry, in the home and our cars, and powering our aircraft. It will also put the oil industry out of business.
 
sacamojus
Posts: 186
Joined: Sat Dec 30, 2006 1:24 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 4:52 pm

Fission: No

Fusion much greater possibility, but by then we will have totaly different styles of propulsion so that a fusion reactor would then be feasible on an aircraft/spacecraft.
 
PADSpot
Posts: 1637
Joined: Sat Jan 15, 2005 11:31 pm

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 5:29 pm

Quoting Jamincan (Reply 18):
I would also be curious how much more environmentally friendly a hydrogen-powered jet would be

The use on the airplane itself is 100% friendly in so much that the residues are just oxygen and water. The question of how you generate the electricity that you need to produce the hydrogen is another one. Water vapour is a non-persistent greenhouse gas, so much less of problem compared to carbon dioxide for example.

[Edited 2007-10-14 10:31:01]
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 6:20 pm

Quoting RFields5421 (Reply 5):
A nuclear reactor is a boiler used to create steam.

Why would you use steam for the aircraft application? Easiest nuclear engine is to just run ram air through the nuclear pile...voila, hot high pressure gas!

Quoting RFields5421 (Reply 5):
A thrust generating jet engine relies on the expansion of the gas/air during combustion to produce thrust.

There is very little expansion during combustion (pressure is essentially constant across the combuster). It's expansion through the nozzle that generates thrust, although on a turbofan you get *far* more thrust from the spinning fan than you do from the core gas.

Quoting PADSpot (Reply 15):
In case I am allowed to make a projection, the most likely case today is that when conventional, petroleum-based jet fuel is no longer a viable source of energy then Hydrogen will become the next jet fuel. It's supply is basically unlimited, it's clean and it can be used in slightly adapted gas turbines as they used today. The major problem being its storage on the airplane.

If petroleum-based jet fuel is no longer available, where are you going to get the hydrogen? The supply of directly usable hydrogen is extremely limited on earth. You need to crack it from something else (typically water), which is an endothermic process, so you need an external power source. When we run out of petroleum, we've got bigger problems than our jet fuel.

My prediction would be that we'll convert over to nuclear/solar/hydro/wind, use hydrogen for non-weight-critical transport applications (cars, ships) and aircraft will be the last holdouts using petroleum and then synthetic petroleum.

Tom.
 
Rj111
Posts: 3007
Joined: Wed Sep 08, 2004 9:02 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 6:25 pm

I watched a programme about this a few years back

The Russians flew a modified Tu-95 (dubbed the Tu-95LAL) with 2 direct cycle nuclear powered jet engines - though the plane wasn't reliant on them as they had in addition two props which could power the plane by themselves. The nuclear engines did run on tests though.

And here it is....

http://jpcolliat.free.fr/x6/images/tu95lal_03.jpg

The big round thing is the reactor.
 
scramjetter
Posts: 62
Joined: Mon Sep 25, 2006 2:57 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 6:29 pm

When the USAF was researching the YB-36 they were looking for crewmembers 'beyond child rearing age.' That might give you an idea of what the risks of development were! The bomber also had compartments with external hooks so that if it crashed, a long crane could be used to extract the crew and reactor!  Wow!

To see how truly insane nuclear propulsion development might have gone, check out SLAM (Project Pluto - Flying Crowbar):

http://www.merkle.com/pluto/pluto.html

It was a treetop Mach 3 open exhaust nuclear cruise missile!!!  eyepopping  It was never officially developed, but who knows what the militaries have actually created.

Conspiracy Alert:  ghost 

Jumping way off-topic, on December 29, 1980 near Dayton, Texas, two women and a young boy (Betty Cash, Vickie and Colby Landrum) had an encounter with a glowing object that was being trailed by military Chinook helicopters. Betty Cash got out of the car and was later hospitalized with acute radiation poisoning. There were burn marks all over the roadway. Bergstrom AFB officials denied any knowledge.

I only mention this because I have researched the topic of exotic propulsion systems for years. The incident may not have been nuclear and it may not have actually occured. Maybe she just wandered into a full body microwave. Like I said, who knows what has really been developed.
 
SMcC
Posts: 37
Joined: Sun Sep 24, 2000 8:57 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 7:55 pm

You got it Sacamojus.
Fusion will be the technological break through that will lead to safe and environmentally friendly application of nuclear power.
 
User avatar
Stitch
Posts: 26728
Joined: Wed Jul 06, 2005 4:26 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 8:01 pm

Quoting SMcC (Reply 30):
Fusion will be the technological break through that will lead to safe and environmentally friendly application of nuclear power.

However, it will likely be confined to ground-side power plants for quite some time. On the plus side, that just frees up fossil fuels for more "portable" applications, like airplanes.
 
nzrich
Posts: 1105
Joined: Mon Dec 05, 2005 9:51 pm

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 8:07 pm

Quoting LTBEWR (Reply 19):
and 3) many countries would ban it from flying over their countries.

Correct ie New Zealand that is 100% totally nuclear free ..That means any airline operating to NZ would have to have at least some non nuclear powered aircraft ..Making their fleet buying more complicated also and planning also .. Swapping aircraft last minute may be difficult also with some countries allowing or not nuclear aircraft etc etc .. Also we all know that some airports can be very turbulent going into imagine flying in on a potential nuclear bomb in bad turbulence ..
"Pride of the pacific"
 
User avatar
malaysia
Posts: 2644
Joined: Wed Nov 03, 1999 3:26 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 8:15 pm

I saw how it can be tested with Chimpanzees and maybe the same behavior will be seen in the cabin crew on the plane. oh wait that was Project X Big grin
There Are Those Who Believe That There May Yet Be Other Airlines Who Even Now Fight To Survive Beyond The Heavens
 
User avatar
Starlionblue
Posts: 19636
Joined: Fri Feb 27, 2004 9:54 pm

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 11:01 pm

Quoting AA7295 (Reply 8):
Can you imagine the terrorism risk? Even if they were shot down from the sky, or blown up mid air.

Consider how safely guarded nuclear powerplants are and then imagine having a flying nuclear power plant. I don't see it ever happening unless there is some magical technology that can immediately mitigate the blast of a nuclear weapon.

As far as I know nuclear power doesn't work that way. Even if the plane blew up, there would be no bomb type nuclear explosion.

However, the fallout would be very bad in case the reactor vessel ruptured and spread stuff all over the place.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
SMcC
Posts: 37
Joined: Sun Sep 24, 2000 8:57 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 11:27 pm

Maybe I'm looking a little to further into the future, but imagine not only a very safe power source and environmentally friendly, but also one that comes in a small package. Look at the way computers have shrunk over the past 30 - 40 years. Yes, on a grand scale, they will power our cities, but with the right development ...fusion power for airplanes, big and small ...fusion power for cars, trains, remotely located houses, etc.
 
User avatar
Stitch
Posts: 26728
Joined: Wed Jul 06, 2005 4:26 am

RE: Nuclear Powered Aircraft In Future?

Sun Oct 14, 2007 11:30 pm

Quoting Starlionblue (Reply 34):
As far as I know nuclear power doesn't work that way. Even if the plane blew up, there would be no bomb type nuclear explosion. However, the fallout would be very bad in case the reactor vessel ruptured and spread stuff all over the place.

Correct.

Nuclear reactor piles are designed in such a way that they cannot go "super critical" and create a nuclear detonation. Even if you pulled every control rod out and tossed it a few miles, there would not be a runaway nuclear reaction.
 
Simps747
Posts: 31
Joined: Mon Jun 25, 2007 10:35 am

RE: Nuclear Powered Aircraft In Future?

Mon Oct 15, 2007 1:19 am

What about a Pebble Bed Reactor? It would still need the shielding due to the radiation, but the Pebble Bed design eliminates the need to have two seperate water systems as the liguid is replaced by a gas. I realize that Wikipedia is not exactly a reliable source, however the article on Pebble Bed Reactors specifically mentions using modified variants to power vehicles.

Cheers,
 
rfields5421
Posts: 5940
Joined: Thu Jul 19, 2007 12:45 am

RE: Nuclear Powered Aircraft In Future?

Mon Oct 15, 2007 1:56 am

Quoting Stitch (Reply 36):
Nuclear reactor piles are designed in such a way that they cannot go "super critical" and create a nuclear detonation. Even if you pulled every control rod out and tossed it a few miles, there would not be a runaway nuclear reaction.

No one except those who failed ninth grade science is worried about a nuclear detonation, even a dirty bomb type runaway reaction.

The problem is possible fracture of the containment in an aircraft crash and distribution of fuel rods, among other things, across the environment. Also any part of the reactor or the system used to transfer energy from the nuclear reaction to the propulsion system become irradiated and a dangerous source of radiation poisoning.

As much as we might wish it - there is probably no way to make a nuclear power source completely impossible to fracture containment - without making it heavier than the aircraft itself.

By contrast, nuclear weapons are very easy protect from damage with relatively little shielding. They contain much lower volumes of radioactive material. They are not designed to operate at controlled levels of a chain reaction.

The Damascus explosion showed how well those warheads are constructed and protected against accidental release of nuclear material. The reason it took so long to find the warhead was that there was no radiation leakage. If one was going to go off accidentally - being punched through the blast doors of a silo would have done it.
 
Phoenix9
Topic Author
Posts: 2024
Joined: Tue Aug 28, 2007 8:25 pm

RE: Nuclear Powered Aircraft In Future?

Mon Oct 15, 2007 2:46 am

Thanks for all your insightful ideas and comments!

As for the amount of "fuel" required will be quite less:

http://library.thinkquest.org/22361/energy/reactor.htm

According to this site, 1 cubic foot of uranium has the same energy as 7.2 million barrels of oil (crude I assume) and that only a fraction of this energy is harnessed in today's reactors. That means that the actual amount of uranium required to power a jet should be relatively small ( few grams??) which could also help mitigate the radiation produced.

With flying cost being reduced by such fuel alternatives, airlines will be able to offer cheaper seats and generate more pax and revenue. And the direction the plane design is taking now (larger sizes: A380, 747-8 etc.) we may have a plane large enough to carry a decent payload while being powered by a reactor.


Maybe one day we will have highly efficient and portable reactors that can be used in airplanes, cars etc. etc. Granted that all the other problems mentioned above are take care of as well.

[Edited 2007-10-14 19:52:03]
Life only makes sense when you look at it backwards.
 
Phoenix9
Topic Author
Posts: 2024
Joined: Tue Aug 28, 2007 8:25 pm

RE: Nuclear Powered Aircraft In Future?

Mon Oct 15, 2007 3:24 am

I just checked google patents and came up with this:

http://www.google.com/patents?id=jdg...AAAEBAJ&dq=nuclear+aircraft&num=50


Apparently, there is already a patent for nuclear powered aircraft and it discusses the weight distribution.
Life only makes sense when you look at it backwards.
 
rampart
Posts: 1800
Joined: Sun Aug 07, 2005 5:58 am

RE: Nuclear Powered Aircraft In Future?

Mon Oct 15, 2007 3:34 am

Quoting RTFM (Reply 10):
Quoting Tdscanuck (Reply 4):
It can, and has, been done on a military prototype.

The reactor that was carried on the B36 never actually powered the a/c as far as I am aware. More info on Wikipedia here:

http://en.wikipedia.org/wiki/B36#Experiments

I don't think that there has ever been an a/c powered by a nuclear power plant....

Also not making it to prototype stage, there was a proposal to convert a Saunders Roe Princess flying boat into a nuclear powered demonstator. The Princess was way out of date anyhow, so they were trying to salvage some usefulness out of it. The hull size would have been suffiicient to house a reactor and fuel. I've never seen any actual designs.

-Rampart
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Nuclear Powered Aircraft In Future?

Mon Oct 15, 2007 4:47 am

Quoting Phoenix9 (Reply 39):
http://library.thinkquest.org/22361/energy/reactor.htm

According to this site, 1 cubic foot of uranium has the same energy as 7.2 million barrels of oil (crude I assume) and that only a fraction of this energy is harnessed in today's reactors. That means that the actual amount of uranium required to power a jet should be relatively small ( few grams??) which could also help mitigate the radiation produced.

The limiting factor for an aircraft isn't really energy density, it's power density. You might have enough energy for the flight in a fraction of gram but it's very unlikely that such a small source could provide the power you need.

Tom.
 
lehpron
Posts: 6846
Joined: Tue Jul 10, 2001 3:42 am

RE: Nuclear Powered Aircraft In Future?

Mon Oct 15, 2007 5:21 am

One, its been done, on a military airplane engine about 50 years ago. It didn't fly, but the enignes was test fired.

Quoting Phoenix9 (Thread starter):
Why can't we have nuclear powered aircraft while nuclear power has been used in ships, submarines etc.?

Those vehicles are military, there are not civilian cruiseliners or anything with nuclear power plants inside. Ships are giant, weighing over 10-100 times the A380.

Quoting Phoenix9 (Thread starter):
Can't we have a "mini" reactor on a plane that can generate the energy required to power the turbines?

Compressing a nuclear reactor in it's present form, to something that can be fit on an airplane is really beyond our current technology.

From an economical stand point, the best way to make nuclear powerplants cost effective is to make them big. I suppose if a boat load on money went into it, then yes, we'd have our own Mr. Fusion Home Energy Reactors, like in the movie Back to the Future, part 2.

This is, of course, separate from the paranoia and hype surrounding nuclear power.
The meaning of life is curiosity; we were put on this planet to explore opportunities.
 
PADSpot
Posts: 1637
Joined: Sat Jan 15, 2005 11:31 pm

RE: Nuclear Powered Aircraft In Future?

Mon Oct 15, 2007 11:07 am

Quoting Tdscanuck (Reply 27):
If petroleum-based jet fuel is no longer available, where are you going to get the hydrogen? The supply of directly usable hydrogen is extremely limited on earth. You need to crack it from something else (typically water), which is an endothermic process, so you need an external power source. When we run out of petroleum, we've got bigger problems than our jet fuel.

Yes, just as I wrote in the post above your post. Hydrogen must seen as some sort of intermediate source of energy. You need to generate it with electrical power. As we can deem nuclear energy as practically unlimited, there is no problem of producing enough hydrogen. If we look far enough into the future we could also get it from space where, where hydrogen is also available in abundance.
 
Grunf
Posts: 45
Joined: Fri Jan 12, 2007 9:47 am

RE: Nuclear Powered Aircraft In Future?

Mon Oct 15, 2007 1:01 pm

Quoting PADSpot (Reply 26):

The use on the airplane itself is 100% friendly in so much that the residues are just oxygen and water. The question of how you generate the electricity that you need to produce the hydrogen is another one. Water vapour is a non-persistent greenhouse gas, so much less of problem compared to carbon dioxide for example.

Nope. Air contains huge amounts of nitrogen, and burning hydrogen produces hige quantities of NOx as well as water. Also, it's hard to store needed amounts of hydrogen. It's volumetric energy density is low...you either need to keep it cooled or under very high pressure.
Drink more milk, less kerosene!
 
flyingcat
Posts: 528
Joined: Tue May 29, 2007 10:33 am

RE: Nuclear Powered Aircraft In Future?

Mon Oct 15, 2007 1:14 pm

About 3 or 4 years ago in Popular Mechanics the feature article was a nuclear powered civil aircraft. I do not remember all the details but the idea was to use a radio active source to convert its xrays directly to electricity to power an engine. The idea was to eliminate the use of the need for cooling system. Also by providing indirect energy there would be no direct nuclear particles released in the atmosphere. The design would eliminate the need for bulky shielding. the closest comparison I believe is the Cassini space probe. It uses Plutonium isotopes and it subsequent decay to directly generate electricity. I believe the hypothetical model was a prop powered by electricity.
 
jamincan
Posts: 573
Joined: Mon Aug 21, 2006 9:28 am

RE: Nuclear Powered Aircraft In Future?

Mon Oct 15, 2007 1:18 pm

You know, plenty of spacecraft use nuclear power, so it must be possible for the reactor to be miniaturized quite a bit. I'm not sure what the requirements for shielding are, but it would have to be enough to not interfere with or damage the electronic components.
 
rfields5421
Posts: 5940
Joined: Thu Jul 19, 2007 12:45 am

RE: Nuclear Powered Aircraft In Future?

Mon Oct 15, 2007 1:58 pm

Quoting Jamincan (Reply 47):
You know, plenty of spacecraft use nuclear power,

I'd argue with the world plenty - but there have been some in the past.

They use nuclear materials for generation of electical power. They do not have critical mass for a sustainable nuclear reaction. Their power generation capacity is relatively small - but long lasting.

They do not use nuclear power for propulsion to obtain orbit.
 
User avatar
Stitch
Posts: 26728
Joined: Wed Jul 06, 2005 4:26 am

RE: Nuclear Powered Aircraft In Future?

Mon Oct 15, 2007 3:28 pm

Quoting Jamincan (Reply 47):
You know, plenty of spacecraft use nuclear power, so it must be possible for the reactor to be miniaturized quite a bit.

However, they draw a significant (orders of magnitude) less power then what a commercial airliner needs to take-off and cruise. Even Cassini, which I believe has the largest electrical draw of any spacecraft launched (at least unmanned), needs almost nothing in compared to getting a 737 off the ground and to cruising altitude and speed, to say nothing of a 747.

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos