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It needs to be thoroughly mixed to a statistical level to be used as fuel in a reactor as lumps of higher and lower enrichment within fuel pellets could cause some odd radiological and physical problems. Converting HEU to UF6 makes the mixing easier and more predictable. Of course we could stop guessing and look up how the downblending process was actually achieved...

http://www.usec.com/educationa...

Conversion to UF6 and then "mixed with other material". They're not specific about whether this "other material" was depleted UF6 or regular UF6 produced from minehead yellowcake. Either would be available to the downblenders and would work as well but I don't know the intricacies.

ad hominem, first line. We're off to a great start already.

I'm sorry if you felt that was a personal attack, but I only meant that your view wasn't "a critical and honest view of the entire cycle" which is what you yourself claimed. I don't think that's an ad hominem in the normal sense. I certainly didn't attack you directly about something unrelated to the argument, which is what an ad hominem normally is.

So you're saying that all the problems with ultracentrifuge technology has been solved, it's commercially implemented on an industrial scale in America and that Paducah has been shut down. Before you call me a liar you could send some links supporting your claims as they look like fiction to me.

The only thing I read about CFC use in the enrichment process came from here: http://neinuclearnotes.blogspot.com/2005/07/usec-response-on-caldicotts-cfc.html

My point in bringing it up was not that you were wrong, but that you were not being critical and honest. You should have mentioned that CFCs are currently used in the refinement process but that the plants responsible for them were designed and built in the 1950s before CFCs were even on the radar. Further, efforts are underway to develop a new process that does not use CFCs. And already, the CFC use was reduced by 2/3 since 2001.

Digging a bit further, check out this page: http://www.usec.com/americancentrifuge.htm

They've been working on this for years, but this year in March they have made significant progress:
"Approximately two dozen AC100 machines are operating in a cascade in a commercial cascade plant configuration, which demonstrates USEC’s strategic suppliers' capability to manufacture production ready centrifuge machines and provides the Company with significant additional operational data. This is an important accomplishment in USEC’s efforts to respond to DOE’s technical concerns."

Do you think your remarks, which left out even a mere mention of these developments, were critical and honest about the requirement of CFCs in uranium production? Otherwise, did you run across that information and find something conflicting and credible to reject USEC's claims, and then decide the whole thing is not worth mentioning? Presenting pertinent facts and honest reporting about *both sides* is essential to being critical and honest.

Energy return is already factored into the cost of energy and the operational cost of the plant.

citation please.

Citation? That seems like basic economics and common sense to me. The energy used to gather and refine the fuel obviously costs money. The plants that eventually buy the fuel then sell the electricity produced from that fuel. As energy return goes down, the price per unit has to go up. To make it obvious to your common sense, if it took a million barrels of oil to produce 1 gram of uranium, what would happen to the price of electricity?

I guess you just don't get it, later I might address some of your other points but I'm short on time so I'll summarise. You have provided no evidence to support your assertions. What I provided you were the facts as discovered. If you are going to persist with ad hominem attacks your "argument" really has no credibility.

Wow, you are really sensitive to ad hominems, but you call me "George Bush" which is quite obviously an ad hominem. At least mine was in response to a claim you actually made.

Anyway I doubt you'll accept the evidence I've linked to. I'll note that the evidence you quoted did not support any of your claims. It was merely some information about the supply of uranium. It said nothing about energy return or CFCs. The thing is, I accepted what facts sounded reasonable (the hard vs soft ore was inte

Depending on where you get your figures, as much of 50% of US nuclear power is generated from recycled Soviet uranium, either extracted from decommissioned warheads or excess manufactured product that was in the pipeline at the time of collapse. The US also has a large number of vintage-era nuclear weapons that are no longer considered militarily viable (the trigger mechanisms decay quite a bit) and so could be recycled. Finally, if the going ever gets really bad, we can always reprocess our spent fuel for Plutonium and/or use breeder reactors to make the stuff - this is the primary mode in which the Japanese nuclear industry sustains itself without outside supply, although the cheap price of Uranium makes them feel kind of dumb.

In short, the US does not need to import a single gram of fissile material to run indefinitely. Solar/Wind/etc. . are fine ideas for the long term but do not meet our power needs today. We should absolutely invest in these alternative technologies and, while we are at it, invest in conservation and efficiency. Unfortunately, right now, we are making almost 50% of our power from coal that is massively environmentally destructive from the second it is strip-mined out of the ground to its large final carbon contribution. Nuclear power is the only technology currently available that can put a dent in coal usage. If you show me an alternative that can scale to 400 TerraWattHours, I'll withdraw that claim.

References:
http://www.eia.doe.gov/cneaf/electricity/epm/epm_sum.html
http://www.usec.com/v2001_02/Content/News/NewsTemplate.asp?page=/v2001_02/Content/News/NewsFiles/04-13-03.htm
http://www.defencetalk.com/forums/archive/index.php/t-215.html

there is no contradiction there, if that's what you are implying.

Consider that the Space Shuffle is actually a glider over most of the re-entry (called glide-approach).

A cruise missile is a jet-propelled glider... as opposed to a Russian Satan ss-18, which is a jet-propelled ballista, though such things may use fins and such for stabilization.

In other words, anything that uses wings for flying (and not solely for manuvering e.g. a fighter during afterburn) is a glider.

This might well be vapourware (if you'll pardon the pun), but isn't it also possible that Silex has figured out things that the project you worked on missed back in the 1980s?

Mind you, USEC was an early investor in Silex, but has decided to instead go with centrifuges for their new enrichment plant, so clearly they came to a different conclusion.

However, it's a LONG way from lab benchtop enrichment experiments to a functioning enrichment plant. And once you get to that functioning enrichment plant, there's the question of whether or not it was economically justifiable to build in the first place. This is where the American effort "failed" - even on paper, it never made sense to pursue this technology because it was just too expensive. Sure, you need thousands of high-precision centrifuges to run an enrichment cascade. This was still cheaper than building a laser enrichment plant.

The designs for a uranium laser enrichment plant ON AN INDUSTRIAL SCALE are not for the fainthearted. YOu've got to have the uranium in a gaseous state. That means heating it so hot that not only do you have a pool of molten uranium, but it's BOILING. The laser is going through the HOT uranium "steam". The only material that can stand up to these temperatures is pure graphite. The design becomes like a series of rain gutters on a house that carries "more enriched" and "less enriched" streams of molten uranium back for reboiling. Somehow you've got to figure out a way of putting optical ports into this hellhole to fire the laser beams in. The laser beams themselves are a weird wavelength (green) and takes some really expensive gear to generate at all, much less with intense enough power to penetrate deeply into a fog of molten uranium. Doing all of this cheaply? Good luck.

And in the background overshadowing enrichment plant economics was and is the fact that nuclear power plants are still just too expensive a way to generate electricity (primarily due to regulatory costs) compared to coal and natural gas turbine plants. The expected boom in nuclear power plant construction forcast in the 1970s and early 1980s never materialized, mainly due to Thre Mile Island and Chernobyl, and so the need for new-fangled enrichment technology as a support industry never materialized with it either.

Right now the cheapest way to come up with fuel for a nuclear power plant is not laser enrichment or even centrifuge enrichment. It's diluting old Russian warheads, all 30,000 of them, down from 93% enriched uranium back to 3% uranium. This, along with all those Russian brides American men now have access to, are the REAL spoils of winning the Cold War.

I have seen these comments about the "external" carbon costs of nuclear power plants -- the claims are never supported.

It depends which claims you listen to. Some are based on assuming that all of the known high-grade ore in the world has been mined, and so the world has to rely on lower-grade ore, which requires more refining.

But if you want a figure, Wikipedia notes that at peak capacity, the Paducah enrichment plant (which I believe is the only one operating in the US at the moment) consumes over 3000MW of electricity. USEC's web site confirms this. Even if they only use about 2000MW most of the time, that's still two large coal power stations just for enrichment. Coal, by comparison, doesn't need to be enriched. On the other hand, you need less Uranium for the same amount of power than you do for coal, so it's a bit less polluting to mine.

I do agree that nuclear power is cleaner than fossil fuels. I will provisionally retract the claim that nuclear fuels take the same amount of energy to prepare as coal (it seems like it's actually more, but I can't find any hard data). My point is simply that it's not as clean as some people think.

Some day the world might have an enrichment plant which runs off its own breeder reactor. But at the moment, it doesn't.