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Subject: Depleted Uranium Decision rss

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Brandon Tibbetts
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In a number of other posts there has been some discussion about the use of depleted uranium in reactors to produce plutonium. This has proven to be historically inaccurate (not attempted until the 1960s or so) - but I've left it in so far as the goal of the design is to be alternate history anyway. I've proposed the idea that depleted uranium to plutonium is known to be a viable approach (google "fast breeder reactor") and that it might have been explored during the Manhattan Project if uranium supplies had been less abundant.

Well I've reached a decision. Viable or no, it is this text from http://www.fact-index.com/f/fa/fast_breeder.html that sealed the deal for me:

Quote:
"However, to date all known weapons programs have used far more easily built thermal reactors to produce plutonium."


If it just isn't done in the context of a weapons program - even today - then I can't bear to have it in my design.

Now, the removal of this concept would also remove an interesting element to the gameplay - the synergy of 2 different technologies. I'm shooting for 3 potential grand strategies here: all out uranium enrichment, all out plutonium production, and both. Without the synergy, there is no "both."

But I may have a solution. Natural uranium is reactor fuel, but enriched uranium is more potent reactor fuel. In the real Manhattan Project, America barely enriched enough uranium for 1 bomb. But what if they hadn't made enough? That was a very real possibility. What if they only had 20% of what they needed?

Could they then have used the enriched uranium not as a bomb, but as reactor fuel to produce plutonium at an accelerated rate? If this works, it means depleted uranium is gone from the game, but instead there will be a conversion option from enriched uranium to "uranium" in the reactor supply that would not have to be mined.

 
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Frank Eisenhauer
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Could they then have used the enriched uranium not as a bomb, but as reactor fuel to produce plutonium at an accelerated rate? If this works, it means depleted uranium is gone from the game, but instead there will be a conversion option from enriched uranium to "uranium" in the reactor supply that would not have to be mined.

As far as I know they kind of did that early on and it proofed too much of a strain on the already meager resources. Don't forget: In the beginning they didn't know which way would give them enough "fuel" for a bomb. For me the marvel of the Manhattan Project is the fact that the hugely difficult logistics in the end worked out. There was a tremendous time preasure because nobody knew exactly how far the garmans had gotten with their bomb and because of the expected high causualty numbers of a conventional attack on the japanese mainland.
 
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Brandon Tibbetts
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eisenphx wrote:
As far as I know they kind of did that [use enriched uranium as reactor fuel] early on and it proofed too much of a strain on the already meager resources.


That is my understanding as well. They needed every bit they could get for "Little Boy," and were right on the money with that amount.

But my main question is, suppose the amount of u-235 had been far short of what was needed for the bomb, and they predicted this well before the quantities of plutonium were sufficient. Could they then have used the enriched uranium they had produced to accelerate their plutonium production instead?
 
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Frank Eisenhauer
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But my main question is, suppose the amount of u-235 had been far short of what was needed for the bomb, and they predicted this well before the quantities of plutonium were sufficient. Could they then have used the enriched uranium they had produced to accelerate their plutonium production instead?

That might be the wrong question. The correct question (IMHO) should be: Which of the two approaches would have given them a functioning nuclear device faster? That would have been the way the project manager would have had to choose.
I think you also have to factor in that there would have been a reasonable expectation to get more U-235 from german / europian sources after the victory in Europe. The enrichment facilities for Manhattan where just reaching their full capacities at that time as well.
 
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Brandon Tibbetts
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schmanthony wrote:
But my main question is, suppose the amount of u-235 had been far short of what was needed for the bomb, and they predicted this well before the quantities of plutonium were sufficient. Could they then have used the enriched uranium they had produced to accelerate their plutonium production instead?


eisenphx wrote:
That might be the wrong question. The correct question (IMHO) should be: Which of the two approaches would have given them a functioning nuclear device faster?


Agreed, and I think we're talking about the same thing. Early in the process it seems desirable to make all you can of both, planning to scrap one plan later if necessary. So let's say uranium enrichment had failed to produce a bomb. It still may have produced a quantity of u-235. I'm proposing that this quantity of u-235 might then have been a vehicle to producing plutonium faster, rather than just stockpiling it.

eisenphx wrote:
I think you also have to factor in that there would have been a reasonable expectation to get more U-235 from german / europian sources after the victory in Europe.


The scope of the game ends at capability to wage nuclear war. But are you saying you think the U.S. government would have stockpiled its u-235 had it not been enough for a bomb, expecting they'd make more or buy more later? Maybe... but then wouldn't this be opposed to goal #1: make bombs as fast as you can for immediate deployment?
 
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Frank Eisenhauer
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But are you saying you think the U.S. government would have stockpiled its u-235 had it not been enough for a bomb, expecting they'd make more or buy more later? Maybe... but then wouldn't this be opposed to goal #1: make bombs as fast as you can for immediate deployment?

It may have actually done exactly that. The question would be wether government agencies knew how much U-235 the US-Army could liberate in which time frame in Europe (did they know where and how much of it was stored?) It depends on wether going for those stockpiles would have given them the Bomb faster than switching to the alternate fision fuel.

I don't think you can simulate this in your game without sacrificing the minimun luck + open information approach.

I just noticed I haven't commented on the game yet at all :
I think this is a brilliant game idea and so far it looks very nice. Hope you will be able to solve your conundrum!

Edit: Spelling, as usual.
 
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