Along those same lines (low level fuel pieces assembled in a destruction-proof container), aren't various companies working on micro-reactors or "nuclear batteries"?

http://newenergyandfuel.com/http:/newenergyandfuel/com/2008/...

"The fuel is uranium of a type that isn’t worth much to a terrorist. The reactor operates with principles that shut themselves down so meltdowns and other horrors for the neighbors simply don’t exist."

I'm not saying all the bugs are worked out. But it looks like enough has changed since TMI that we could/should take an honest, open look at what we can do with nuclear now that we couldn't back then. At least to me it has.

The biggest issue is radioactive contamination in case of an ordinary plane crash, and parachuting a reactor doesn't sound like especially convincing solution: when planes crash, it is usually because a lot of things go wrong onboard, with parachuting system possibly being one of them.

I think we'll be much better off investing into development of new generation of speed trains: they can easily be made electric (thus taking advantage of cheap nuclear energy), riding on electro-magnetic fields friction-free at crazy speeds.

Not so, it's a lot easier to put extra safety equipment on the ground then on an airplane.

I quite agree that parachuting the reactor is not going to work - if you were flying the thing, and you had a 50% chance of saving the plane if you had a power plant, but a 100% chance of crashing if you let it drop - would you do it?

The military is trained for such choices, civilians are not.

Also, what about a surface-to-air missile?

I assume this means that an aircraft crash involving a pebble-bed reactor _not_ inside a big concrete building could be bad. The second layer of containment (two-meter thick walls) also sounds pretty difficult to make fly.

in the worst-case scenario, if the armour plating around the reactor was pierced there would be a risk of radioactive contamination over a few square miles

And that's supposed to make us feel better? Fun fact: the area of Manhattan is 23 square miles, and 1.8 million people live there.

Seriously, I'm a supporter of nuclear power if it's used sensibly, but strapping wings to nuclear reactors and sending a couple of hundred to fly over every city on Earth every day doesn't sound like "sensible" to me.

i think it would be safer to have the nuclear reactors and fuel on the ground and to somehow transmit that energy to the plane.

another option would be lightweight, high density batteries that can be charged in minutes. planes could then at first fly several hundred miles, touchdown, refuel and then take off without much time loss. CNT (carbon nanotubes) might produce batteries/capacitors that are upto the 'charge'.

So, even if these planes were to exist, we would need to build a new network of remote nuclear airports (nukeports) miles away from any urban development ---plus a transportation infrastructure to shuttle between the nukeport and urban centers.

The cost wouldn't be the flight itself, but the adhoc transportation network of several dozen miles from the nukeport to urban centers. It could take several hours to get from the nukeport to the city in poor traffic. That's why this is impractical for civilian use, though maybe it could work for mass military transport or freight.

[1] This assertion definitely excludes small potatoes airports that earn their international name by serving the one country closest to them (i.e. small town WY or MT airports serving Canada).

Perhaps my perspective is a bit skewed by living in Virginia though, development around here is really like anywhere else in the country.

No, most airports are within a few miles of major metropolitan areas because that's where people are located, and airports themselves are often significant bastions of human infrastructure.

Further, unlike an ordinary plane crash, a nuclear incident even confined within the bounds airport would close that airport for years, if not permanently. No major airport would risk shutting itself down forever.

Very well, small, remote airports may be qualified to service nuclear planes, but that defeats the purpose of massive transit of people between major urban centers.

"something to do with runways taking up space"

Don't troll.

Airports need to be in places where there is enough space for the airplanes to take off and land. This means that the airports themselves need to be built in places where there is enough space for runways and there are no tall structures to interfere with low-flying aircraft. At the time of building, this means significantly outside urban centers and it means that for a ways around, buildings can only be a few dozen stories tall.

As time passes, commerce and industry builds up around airports, but, in general, large airports are not located within major urban centers. They are at least as remote as many nuclear power facilities. While some airports would then be out of limits, many could be quite feasible.

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Now given that the primary purpose of nuclear planes would not be transportation between major cities but rather intercontinental flight, which, in case you've never been on one, already requires switching airports a number of times before you get to where you want to go, This could conceivably be quite practical. You would have one or two in the Us, one in Canada, One or two in Europe, one in Russia, one in China, one in Australia, etc. and you would transfer flights to get to where you were going. This is how intercontinental flight already works, so I don't see how it is infeasible or self defeating.

Much better to use nuclear power for homes and electric cars, and save the liquid fuels for airplanes.

Did you read the section on tolerances, and the temperatures? Do you really think such a thing would be reliable for day to day running on an airplane?

It's not impossible of course, but it's not practical, and it's a waste of money. Use the nuclear power on earth, and save the liquid fuels for the air.

The ramjet lives on, but it's not nuclear powered, and don't they call it the 'scramjet' now?

(from wikipedia on Scramjet)

Actually powering a jet from a reactor is a lot more complicated.

albeit the fact that they the B-36 bombers themselves ______were powered by kerosene_______ despite the availablility of nuclear power since it wasn't intended to be anything more than a proof-of-concept flight

You wrote: "proved beyond the shadow of the doubt that it's both doable and feasible" - and at the same time that they didn't do it.

So how did they prove "beyond the shadow of the doubt" something they didn't even do?

That made so little sense I assumed you didn't realize they didn't power the engines from the reactor.

Edit: maybe you don't realize that carrying the nuclear plant is the easy part (heavy lift vehicles exist after all), powering the engines is the very hard part.

As mentioned elsewhere already, this is commonly referred to as a "ram-jet". The heat in such an engine usually comes from combustion, but any old heat source will do.

And that's NOT a ram-jet. Part of the thrust in a ram jet comes from the liquid fuel suddenly growing much larger as it's vaporized.

Using air directly would mean heating it to thousands of degrees. Then you need a material that can handle such temperatures (which don't exist), and still contain the nuclear fuel. And at those temperatures your fuel is molten.

When you burn liquid fuel - it burns at a thousand degrees or so, but then expands rapidly (and cools), so you don't actually have to contain anything at that temperature.

But if you heat air you do - and that's not easy.

Oh, and the entire point of ram and scram jets, is to provide oxygen without blowing out the flame (which is why it's so hard to do). That doesn't apply here.

Edit: Read this http://en.wikipedia.org/wiki/Nuclear_thermal_rocket and you'll see how hard it is. And they had control of the working fluid, you are proposing plain air.

Nuclear powered ramjets

    Main article: Project Pluto

Honestly, though, a hydrogen powered plane is a more likely and more physically reasonable system. Hydrogen has a very high specific energy, and energy density isn't nearly as important as weight in a plane.