Depleted Uranium Munitions

[Mercedes Benzene]

You beat me to it Craig. :)

 

 

 

In the wiki article I linked to in my last post, it says that the U-238 is converted into Plutonium-239. Is that a typo?

 

I don't think that's a typo. It's very possible to transmute U-238 to Pu-239, and reading up on breeder reactors, it seems that is exactly what happens.

[freeztar]

So what about the U-235 Craig brought up?

Perhaps it's in one of the links, but to be honest I did not read them all, just skimmed. I'm trying to get as much Hypo time in as possible before the fiancee shows up and demands all my attention, so I've been comparably light on the reading/researching tonight. :)

[Moontanman]

From the linked-to article:and 2 paragraphs earlierFast breeder reactors can use the depleted uranium (U-238) produced as a by-product of producing enriched uranium (U-235), but their primary energy source is PU-238, which is produced in U-235 reactors, taken from dismantled nuclear bombs, or from U-238 that has been transformed (“bred”) by the FBR.

 

U-238 in a FBR isn’t fuel, in the usual sense, but is transformed into fuel by its plutonium core, making a system of FBRs and reprocessing plants very efficient.

 

A FBR won’t work (nor will any reactor) if fueled by depleted uranium alone – it must have enriched plutonium. Depleted uranium is cheap and plentiful, while enriched plutonium is rare, expensive, and available only to a few nations. So I just can’t see how the original claimcan be true. Anybody with the plutonium they need to fuel a FBR will already have more depleted uranium than they need, and won’t be interested in buying it from people who have had their fields littered with it by a passing military, unless through some coincidence of lack of foresight and shooting a lot of depleted uranium projectiles, a nuclear state uses up all its depleted uranium making projectiles. Even if this were to happen, it could make more by enriching uranium for a conventional fission reactor, which it has constant need to do to supply its conventional fission (U-235) reactors.

 

 

the reaction can also be started by thorium isotopes but the main this that once you get the reation started it breeds more and more plutonium to star more reactions. Using like that the supply of plutonium, which by the way when the thorium cycle is it cannot be used for nuclear bombs. Some people think that thorium is the way to go and avoid the whole uranium scare thing. the only reson we now uranium is that this 1950's tecnology and change come slowly to some tecnologies.

[CraigD]

So what about the U-235 Craig brought up?

Uranium is found in nature in various forms, mostly as [ce]UO2[/ce] and [ce]U3O8[/ce]. 99.2742% of the uranium is the isotope U-238, 0.7204% U-235. To get a useful fuel for a conventional fission reactor, these two isotopes are partially separated, usually by spinning them in powerful centrifuges to an ‘enriched” concentration as low as 1% U-235, typically 3 to 5%, or in the case of weapons and high-performance reactors, as high as 90%. The by product is depleted uranium, which typically has less than 0.2% U-235.

In the wiki article I linked to in my last post, it says that the U-238 is converted into Plutonium-239. Is that a typo?

Here’s the neutron capture and decay chain by which U-238 in a breeder reactor is transmuted into Pu-239:

U-238(92p +146n) +1n -> U-239(92p +137n) -> Np-239(93p +136n) -> Pu-239(94p +135n)

 

The half lives of U-239 and Np-239 are about 2.355 and 2.117 days, respectively, so this is a fairly fast chain. The difference in mass is about .0021299 AMU, so it’s about 84 times less energetic than U-235 +1n fission.

 

All of this is common information, available from wikipedia and many other sources, though it takes a bit of digging to put it all together. I’ve been putting together my own enhanced periodic table database tool for the past year, which helps in digging up the data without having to click, copy and paste across a gaggle of webpages.