Nuclear Rockets Moving Along

AKAImBatman writes "Bruce Behrhorst of NuclearSpace.com recently stumbled across a new engine from everyone's favorite Jet Engine maker, Pratt & Whitney. Unlike P&W's previous engines, however, this engine is not a jet, and is powered by Nuclear Fission. It seems that P&W has responded to the need for Mars transportation by inventing the first commercially viable nuclear thermal rocket. They have heavily improved upon the NERVA NRX design from the 60's, and have even solved the graphite ablation problem! With this new engine, it seems that an inexpensive trip to Mars is now firmly within our grasp. Will we rise to the challenge?"

Comments

Safety Question

[higgins]

This isn't meant as a panicky "omg! nucular!" question. But we have seen a few space craft blow up spectacularly. Now, I assume the designers are bright enough that these engines could not actually produce a nuclear explosion, but wouldn't a conventional explosion at high altitude run a high risk of scattering nuclear material all over the place? Is there a good reason I shouldn't be worried about that?

Re:Safety Question

[Reducer2001]

There already was a spacecraft/satelitte that had a nuclear device in that "blew up" in space. The only thing that remained was the nuclear material, still perfectly stored in it's container. I'm sorry for not having a source to back to this up, but I'm at work. Here's a ton of info about this stuff.

Re:Safety Question

[WhiplashII]

The real question here is "how safe is a radiactive substance?" People often try to answer this by saying, we have done X so it isn't possible to have the reactor break, etc. (I mean, it is only for use in space, so it really shouldn't ever be near unshielded humans. Space is already a nastly place filled with radiation.) But everyone knows that humans aren't perfect, we can't forsee everything, etc. So, if the thing blows up and dumps radioactive stuff all over, what happens?

Well, first of all note that the Earth we live on is radioactive. We are constantly subjected to a high dose of radiation, and our bodies are relatively immune to it. In the scenario you mentioned where the radioactive substance is spread across a wide area like a continent, its contribution to the radioactivity levels is dwarfed by Earth's natural radiation. The real problem is concentration, for example if the stuff does not burn up but comes down as small chunks. Each small chunk can hurt or kill a person, depending on the size of the chunk and its level of radioactivity. The object in question would hurt you if you were exposed to it directly (like it fell on your house), but wouldn't kill you right out. You would get sick, go to the hospital and be treated. Your neighbors wouldn't get sick, but would be evacuated (and probably lose their house as well).

Summary: A worst case event could hurt or kill a couple dozen people, just like a normal rocket launch.

Hopeless

[Ford Prefect]

What's wrong with Project Orion? ;-)

I mean, if we're going to go to Mars, we might as well do it properly - even if it does end up filling the atmosphere with radioactive fallout...

Re:Not quite

[Kingpin]

Why should I not fear radioactive material in the atmosphere? Given the track record of shuttles, launchers and what have we - there's obviously a non-negligible chance of accidents happening. In case of such an accident, radioactive debris will fall down, radioactive rain could happen?

So, why should I not be worried? Please enlighten me.

Re: Silly public hysteria

[Control Group]

Please do not lump Project Orion and the Nicaraguan Canal together with nuclear power generation.

Nuclear power generation is self-contained, and only problematic in case of catastrophic failure. The other two are problematic when functioning as designed. Associating the three is precisely what has prevented the use of nuclear power generation.

You of course scare-monger by mentioning nuclear power plant failures, but you'll notice that the world has (shock!) survived just fine. While the death toll from an event like Chernobyl is certainly tragic, there are risks associated with developing any technology. Beyond which, I have the sneaking suspicion that more people have died from the effects of air pollution caused by fossil-fuel power generation than have died due to nuclear reactor failure by orders of magnitude.

I also suspect (based on broad stereotyping, admittedly, so feel free to tell me I'm wrong) that you also buy into global warming as a result of mankind's CO2 production, in which case the death toll from fossil fuel plants will be yet more orders of magnitude higher than would be caused by the occasional nuclear plant failure.

Weirdly apropos

[caveat]

discovery wings is at the moment running a show on Project Pluto, the government's project to develop a nuclear-powered ramjet in the 50s/60s. the research got up to successfully running the full-scale Tory-IIC 500Mw prototype for 5 minutes at 35,000lbs thrust. i realize a ramjet design is different from a thermal rocket design, but does anybody know why 'they' can't use the basic design of the tory reactor, homogenous uranium/beryllium oxide fuel tubes, at the heart of the rocket engine? seems an ideal situation, theres no graphite to ablate and AFAIK the oxide ceramics stand up pretty well to hydrogen.

Re:No chance...

[mwood]

Okay, so what *should* we do with the products of fission? Recycling is not allowed, since this yields a bit of plutonium which automatically causes all nations to start building bombs. You don't want to store it. "Use it" or "throw it away" seem to be the only options. Should we wave a magic wand and make it disappear?

coal is 1ppm - 10ppm Uranium, some bomb grade

[puzzled]

Burning coal puts 25 tons of bomb grade Uranium into the air every year and I forget the exact amount of U238. The U238 gets hit by high energy neutrons from cosmic ray impacts and changes into ... Plutonium.

Launching a little dab of Uranium under highly controlled conditions doesn't seem like such a big deal when you know this fact.

Bah!

[ljavelin]

Note that the engineering term "intrinsically safe" has a substantially different meaning than "inherently safe". Although the terms are used interchangably by some, those who live by the "law of milspecs" never confuse the two.

In any case, it'd be wise for P&W to rename it something other than a nuclear engineer. That's dumb marketing. Hell, they don't call the Army's M1 tank the "nuclear tank", despite its use of depleted uranium.

And anyhow, many jet engine parts use radioactive materials for hardness and during the manufacturing process. This is not news.

Re:Not quite

[NardofDoom]

People were all up in arms about Cassini's launch because it had the largest RTG ever launched. They were afraid that it would break up on launch and spread plutonium all over the planet.

Unfortunately, they ignored the fact that coal burning power plants put more radioactive material into the air every minute than was in the Cassini probe, and that the plutonium wouldn't atomize. It would sink like a rock into the muck at the bottom of the ocean, just like the dozen or so nuclear subs that have been lost. And it would pose no threat to life on Earth.

Nuclear and radiation are buzzwords that freak out people that don't understand. I'm radioactive right now. Should I be buried in a Nevada salt mine or shot into the sun?