[Jay-qu]

sounds good pyro - .71% of natural uranium is the fissionable stuff, enrichment for nuclear reactors normally brings this figure up to around 5% the waste that comes out has 96% Uranium, 1% Plutonium and 3% other fission products. So by simple math 1% of the original 5% of fissionable Uranium is remaining, I think it would be impractical to carry around 100 parts of something when we can only use 1 part of it... maybe 2 if the plutonium can be used.

[TheBigDog]

Could our enriching process separate the parts, sending the hot stuff into the engine, and sending the remains back into the tank? Would we continue to yield 5% good stuff no matter how many times we pass it through the enrighment process? So we have 1/99 product, are streaming this into an "enricher". This device turns that volume into 4/(1/99). The pure 4 are used in the engine, while the rest goes back into the tank. I don't know the enriching process, but could this go on almost indefinatly?

Bill

[Jay-qu]

In short no. U235 is the fissionable stuff(what we want) it accounts for .71% of natural uranium - enriching removes some of the U238 so that U235 now accounts for 5% enough to sustain a chain reaction. After the reactor is done with it, there is only 1% U235 and 1% Plutonium (not sure if this is usefull) the rest is dead mass for our purposes.

[TheBigDog]

How does the enrichment process work? We may want to go past 5% if that is possible. Remember, we are in deep space, so the "safety rules" are different.

Bill

[Jay-qu]

sorry maybe I didnt make it clear - it is enriched to 5% for the purposes of nuclear reactors, I would assume that it is much more for bombs and such. It works be removing useless U238 which accounts for the majority of mass.

[Janus]

Originally Posted by TheBigDog

Who could ask for a better crew than this. I am surrounded by geniouses!



So...

Suggestion: Our tank is filled with spent nuclear fuel that is a single step from being turned back into enriched uranium. This way the whole tank can be filled with the stuff, but in a fairly stable way. As the fuel is brought to the engine it is enriched in line before passing into the engine.
Question: Is that plausible?

I don't see this as saving us any and possibly causing us to lose efficiency. Enriching the fuel will leave us with a lot of waste non-fissionable material, Plus now you have to add the mass of the enriching equipment.

And in answer to your question Janus, The sections are straight. There will be a weird effect near the ends as the gravity will be a bit angular. But we will get used to it. I have them straight because a banana doesn't fly straight. These are assembled on the ground and lauched as completed units. It will add character to the experience. Ever been to "the mystery spot"?

(t-27)

Bill

It depends on how you package the banana. The LEM wasn't exactly aerodynamic either, but they got around that by encasing it in an aerodynamic shell for the period of atmospheric flight.

I really think curved sections would be better. To further argue my point, just look at how good she looks entering Martian orbit with curved sections:


And yes, I have been to the Mystery spot (out at least one of many).

[TheBigDog]

Wowwie-kazowwie!

Janus, that is a great picture! We will figure out how to get the curved secions into space. Maybe they are launched straight and flex into shape when installed? In any event, I am sold on curved sections. Excellent job!

Bill

[Janus]

Originally Posted by Jay-qu

sorry maybe I didnt make it clear - it is enriched to 5% for the purposes of nuclear reactors, I would assume that it is much more for bombs and such. It works be removing useless U238 which accounts for the majority of mass.

Weapons grade uranium is enriched to over 90% U235.

To give an idea of the process, the Uranium is first converted into uranium hexafluoride (UF6) gas, and then either run through a centifuge or a series of diffusion plates to separate the U238 from the U235.

Now, as far as "enriching" nuclear waste goes. typical reactor waste breaks down thusly:

33 tonnes of spent nuclear fuel contains:

31.5 tonnes depleted uranium

1.2 tonnes fission products & actinides

300 kilograms plutonium

Depleted uranium is uranium in which the U235 content has dropped below that usable for a reactor. you might be able to enrich this by extracting this unused U235, but I doubt that you will get more than a few hundred kg.

The fission byproducts are useless to us.

The plutonium is of interest, as a percentage of that will be PU239, which is useful for nuclear detonation devices.

One problem with reactor waste is that many of the of the fission by-products are higly radioactive, and thus the waste is too "hot" to safely handle. You have to wait until these byproducts decay before you can think about processing it.

One possibility would be to use the extracted plutonium and depleted uranium in a fast breeder reactor, which will breed us more plutonium for our fuel.

[Pyrotex]

Originally Posted by Janus

...just look at how good she looks entering Martian orbit with curved sections...

Janus, that is incredibly awesome. You are talented, skilled, perserverant, and artistic. You are probably ambicranial. Both my hats off to you!!!

[TheBigDog]

I am inspired today by some specials on the Science Channel about various planetary explorations. Our voyage aboard the Prophesy will be the envy of them all. It is high time we began to talk about our exploration goals and that we insure we have the correct equipment on board to complete that exploration. I am most interested in heading out and back again. I would to retrace the path of Voyager 2, and visit all of the outer planets. Only instead of sending back still pictures from uncontrolled flybys we will linger as we please; send back full spectrums of analysis; and take samples as we please.

We should have a compliment of landing craft. From "Viking" style landers. To surface rovers. To things akin to Galileo probe of Jupiter's atmosphere. I would like to have a shuttle that can carry a crew and equipment to a planet or moon surface for extended manned exploration. Perhaps some specialized equipment for drilling through ice to try and locate wet seas heated by the core of planets. We should be equipped well enough, and have enough agility with our fine ship to makes and change plans as we go. Lingering where we find things of interest, and moving on when we are satisfied with what we have found.

Some probes might be launched in pairs or small groups to concentrate exploration. Probes on a planet surface, and an orbiting surveyor/relay satellite to communicate information back to earth and to the Prophesy crew. And for key equipment the ability to retrieve our probes, with samples, for more detailed analysis back on the ship, or ultimately, back on earth.

Aside from scientific exploration of our planet, we will be doing research on the matter of sustaining resources aboard a space ship for indefinate time of exploration. This is a matter of research, and while we will attempt to create that environment onboard the Prophesy I acknowledge that it is not plausible on our first attempt. Part of what will change in the outfitting of the ship between each mission will be changes called for in the attempt to amke the ship on each mission more self sufficient. Because we are never going to be more than a few months from earth we do not absolutly need to accomplish this on our first mission. Once we have gained some expertise in this field we will be reay for our first interstellar missions. But I am getting ahead of myself.

Our Astrophysicist, Jay-qu has expressed some interest in going to Jupiter. I plan on spending months in the orbit of Jupiter. With missions to her many moons happeing on a weekly basis. And that before we move on to Saturn, Uranus, Neptune, and maybe even Pluto. All before returning to earth with our bounty of information. So lets get to planning!

I think we should actually begin with a trip around the moon. This is partly symbolic, and partly "sea trials". We will place a satellite in orbit around the moon, along with an automated and manned lander on the moon. Then we will take a trip around the earth with the Prophesy, and retreive our equipment and crews again. Upon evaluation of this manuver we will either go back to earth for changes, or head out toward Mars, and Jupiter, and Saturn... And all this begins in just... 25 days.

So for the short term, what do we want to accomplish on the moon during the checkout of our systems?

Bill (t-25)