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 Post subject: Re: End Game
PostPosted: Nov 06, 2008 3:35 pm 
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Your friendly neighbourhood editor here again.

What would be your effective efficiency if you assumed a 0.5% loss rate to flourination BUT, given that you are assuming batch processing, two-pass flourination?

Would your effective loss rate then simply be (0.5%) ^2? Or would the second pass leak rate be significantly higher? I'm asking because Pu arising from leakage is a shade under 75% of your final TRU inventory (as at final GWe reactor reaching equilibrium) and thus is the gorilla in the room if you want to take things further.

Assuming (very unrealistically, given the physics) that only Pu can be recovered in the second pass at the square root of that loss rate, working out to 7.1%, that drops Pu leakage from 224.9 t to 16.0t, reducing final TRU inventory to 90.7 t, making bulk TRU reduction 95.5 fold, TRU waste per GWe-yr 0.06 kg, and TRU reduction per GW-yr 19,111 fold. That effectively makes your overall Pu leak rate 0.036%, btw.

As for the Pu solubility limit in this reactor configuration, is it 8 t Pu/GWe-yr or 12 t Pu/GWe-yr?

Nitpick: It is metric TONNES, not TONES (cf your graph over time of waste and inventory TRU levels)

If you're assuming 9 billion people at western standards of living, should it not be a nine-fold increase in power output?


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Last edited by Alex Goodwin on Nov 06, 2008 4:55 pm, edited 1 time in total.
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 Post subject: Re: End Game
PostPosted: Nov 06, 2008 4:27 pm 
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Great paper! Publish it!


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 Post subject: Re: End Game
PostPosted: Nov 06, 2008 6:42 pm 
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fnord wrote:
Your friendly neighbourhood editor here again.

What would be your effective efficiency if you assumed a 0.5% loss rate to flourination BUT, given that you are assuming batch processing, two-pass flourination?

Would your effective loss rate then simply be (0.5%) ^2? Or would the second pass leak rate be significantly higher? I'm asking because Pu arising from leakage is a shade under 75% of your final TRU inventory (as at final GWe reactor reaching equilibrium) and thus is the gorilla in the room if you want to take things further.

Assuming (very unrealistically, given the physics) that only Pu can be recovered in the second pass at the square root of that loss rate, working out to 7.1%, that drops Pu leakage from 224.9 t to 16.0t, reducing final TRU inventory to 90.7 t, making bulk TRU reduction 95.5 fold, TRU waste per GWe-yr 0.06 kg, and TRU reduction per GW-yr 19,111 fold. That effectively makes your overall Pu leak rate 0.036%, btw.


Frankly, I don't know. My guess is that you will extract some additional Pu but that it will come with some unwanted fission products. For our application this is perfectly fine. It isn't acceptable for most solid fuel systems.
In the end, I hope the Thorium spent nuclear fuel (primarily fission products in salt with a little bit of Pu etc) gets sent to a central reprocessor that can do a better job. I'm thinking that at this point some of the fission products may be more of a problem than the remaining Pu. As for the end game inventory, I stopped at a single 1 GWe reactor. One could reasonably build a single 100 MWe reactor to reduce the end game inventory another factor of ten (takes around 90 years) and then a single 10 MWe reactor to reduce another factor of ten (in another 90 years). So the end game inventory need never be significant.

The Pu solubility limit in this reactor configuration (1GWe) is estimated at 12t Pu. For safety sake we only allow it to get up to 8t Pu.

If you're assuming 9 billion people at western standards of living, should it not be a nine-fold increase in power output? - Yes but then I'm assuming we get a factor of two power decrease by increasing energy efficiency (led lighting, etc). I think this is a bit optimistic for energy efficiency but it demonstrates the need even if we accomplish a lofty goal for increasing energy efficiency.


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 Post subject: Re: End Game
PostPosted: Nov 06, 2008 10:39 pm 
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I'm more of the opinion that Jevon and his paradox will bite back with a vengeance, wiping out any gains from improved energy efficiency.

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 Post subject: Re: End Game
PostPosted: Nov 07, 2008 12:31 am 
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Thank you for the edits.

Yes abundant, low cost, clean electricity will generate new uses.

Transportation is a huge energy user. If we can reasonably use nuclear reactors as the primary energy source for transportation then we could see demand for 5x what I forecast. But then I received more than one comment that my projections were unbelievable too large. It doesn't really matter. The first 1,000 plants can be started from SNF. Starting additional plants is a problem I'd love to be facing. I am confident we can grow to meet whatever demand.


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 Post subject: Re: End Game
PostPosted: Nov 07, 2008 7:52 pm 
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fnord wrote:
I'm more of the opinion that Jevon and his paradox will bite back with a vengeance, wiping out any gains from improved energy efficiency.

Its a silly observation of the corrolation of efficiency rise and consumption during a time of economic growth. We'll see far more than a ninefold increase in demand over the next several centuries. Conquoring the universe isn't done on the same energy budget as corn farming.


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 Post subject: Re: End Game
PostPosted: Nov 18, 2008 12:08 pm 
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I was reviewing the French paper and noticed that they claimed they had to consume the U233 since it was a significant radioactive source. In this paper, I simply set the uranium aside as if it were depleted uranium. Indeed, the French are correct that U233 is a waste problem and should be consumed. So, it is not time to publish yet - I'll have to revise the shutdown plan but I'm optimistic that the overall conclusion will not be significantly altered.


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 Post subject: Re: End Game
PostPosted: Dec 11, 2008 10:01 pm 
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Anything new happened with your paper, Lars?

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 Post subject: Re: End Game
PostPosted: Dec 11, 2008 11:17 pm 
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Yes. I realized that I have to treat the 233U as dangerous long term wastes fairly similar to 239Pu. So, I had to go back to the simulators and rewrite things and come up with a new strategy. It still works but it takes TIME (like 600 years) to properly clean things up. I'll post it again in a few days when it is at least more readible.


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 Post subject: Re: End Game
PostPosted: Dec 12, 2008 4:30 am 
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OK. Here is the updated paper. It reflects consuming not only the TRU's but also all the uranium inventory. One must be patient! It takes several hundred years to burn everything off but no matter how low you want to take the inventory we can get there in time. My simulation is very limited - I tell it the neutron spectrum and the power level - so I have to keep the fission macro cross-section and the absorbtion macro cross-section constant. There may be optimizations that can speed things up a bit. But the dramatic conclusion is that we can have TONS of power and still generate less TRU wastes that we already plan to put up with.

The best case extraction efficiency David LeBlanc will protest is completely unrealistic and it probably is. But the point is that almost no matter how good one is at extracting TRUs we can reduce the residual inventory to be small by comparison.


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 Post subject: Re: End Game
PostPosted: Dec 12, 2008 11:43 am 
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And here is a nice table but it doesn't quite fit into the purpose of the paper.

TRU Waste generation for 1 GWe-year
LWR NM-TMSR
Element Worst Best Case
Np (kg) 16.2 0.1 0.0001
Pu (kg) 240.4 0.3 0.0003
Am (kg) 4.7 0.006 0.000006
Cm (kg) 1.6 0.002 0.000002
Total TRU Waste 262.9 0.4 0.0004
Total Reduction, fold 650 650,000


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 Post subject: Re: End Game
PostPosted: Dec 12, 2008 2:35 pm 
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Lars wrote:
And here is a nice table but it doesn't quite fit into the purpose of the paper.

Code:
 TRU Waste generation for 1 GWe-year
                       LWR       NM-TMSR
Element                       Worst   Best Case
Np (kg)                16.2    0.1     0.0001
Pu (kg)               240.4    0.3     0.0003
Am (kg)                 4.7    0.006   0.000006
Cm (kg)                 1.6    0.002   0.000002
Total TRU Waste       262.9    0.4     0.0004
Total Reduction, fold         650     650,000


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 Post subject: Re: End Game
PostPosted: Dec 13, 2008 5:13 am 
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Having a look thru the new and improved paper, editing in bits and pieces as I go.

One thing that did jump out was, given the above rates of TRU generation, totalling 216 g/GWe-yr in your worst case, would result in each given reactor generating 60 GWe-yr * 216g/GWe-yr = 12,960 g TRU waste from recycling losses. Given fuel salt loading of at least 5t (in metal content, would be boosted by the rest of the salt), that means you're processing 500 kg/a of metal to get your ten year cycle time.

12.96 kg of TRU waste, being 2.6% of your annual processing capacity, would take an extra 2.6% *365.25 = 9.5 days to process during reactor changeover - the residual 52g of TRU can then be discarded to waste after having accumulated on site for the previous reactor's lifetime. 12.91 kilograms is a drop in a 5 tonne ocean (assuming it doesn't materially affect the final TRU inventory in the new reactor), and also acts to reduce your final TRU stockpile, essentially being a (cheap) second pass, performed on site with the existing cheap'n'nasty processing kit. Even if, due to the much greater relative proportion of FPs in waste, the leak rate is square rooted, becoming 6.4%, that means 820g TRU goes to waste per reactor lifetime and a 12.14 kg drop in the ocean goes into the next reactor - still a further 15.8-fold reduction over your worst case.

A fleet of 9k reactors with a 60 year individual reactor lifetime means that you would average 150 replacements a year - a new reactor would be coming on line, on average, every 58 hours, 27 minutes. In a real-world deployment, would you try to even out the rate of reactor replacements as much as possible, to maintain the industrial, technical and other knowledge, rather than overpaying for surge capacity that may be rarely used? (I don't know of many organisations that will keep a massive capacity idle for 60 years)

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 Post subject: Re: End Game
PostPosted: Dec 13, 2008 8:00 am 
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And here we are.


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 Post subject: Re: End Game
PostPosted: May 24, 2009 9:35 pm 
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Anything new on this front, Lars?

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