Energy From Thorium Discussion Forum

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PostPosted: Apr 07, 2014 11:04 am 
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Cyril R wrote:
Not sure about the specifics, but likely the fuel assemblies are loaded in underwater, then the cask is lifted out, then the water is drained and the thing is bolted or welded tight, then evacuated, then backfilled with helium.

This is essentially the process adopted at AECL's Chalk River Nuclear Laboratories (CRNL) for their FPS project (Fuel Packaging & Storage) for old nuclear fuel from research reactors (mostly NRU and NRX).
In FPS, the old fuel is brought in from its previous storage site using a shielded transfer flask; it is lowered into a pre-positioned stainless steel can inside one of two process units, where the contents are heated (low temperature) and vacuum-dried for up to several days -- with humidity monitored to determine the end of the process. The SS can is then closed with a large screw-on cap and the air inside replaced with argon, through small filling ports. The finished container is then moved to a concrete storage module, using an in-house transfer flask.

FPS was recently completed, after some five years of construction, and is currently undergoing commissioning activities.
There is a brief update and 3 photos of FPS on p.7 of the newsletter Voyageur, at http://www.aecl.ca/site/media/Parent/Voyageur_9-3.pdf
Needless to say, the facility was hugely expensive - far more costly than anything used by commercial nuclear power plants.


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PostPosted: Apr 07, 2014 12:46 pm 
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Needless to say, the facility was hugely expensive - far more costly than anything used by commercial nuclear power plants.


The question is, do you think this has to do with higher materials prices?

From what I've read, materials cost in these things barely shows up. It is usually everything BUT raw materials that make up the price. Even a simple lump of ordinary Portland cement concrete can cost a fortune when 12 managers and 50 "quality control engineers" have something to say about it.


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PostPosted: Apr 08, 2014 8:40 am 
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Cyril R wrote:
The economics of a SNF boiler don't work out. The heat load is small compared to the reactor power and the heat is declining which is annoying if you want to operate a boiler for 20 years. Operating a boiler for 5 years increases the capital cost. Also the low power output means low efficiency in terms of heat engines.

I have suggested 1 yr or time till next fuel change There is enough heat till that time
Decay heat could be 2-5% of fission heat in this period.


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PostPosted: Apr 08, 2014 12:03 pm 
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jagdish wrote:
Cyril R wrote:
The economics of a SNF boiler don't work out. The heat load is small compared to the reactor power and the heat is declining which is annoying if you want to operate a boiler for 20 years. Operating a boiler for 5 years increases the capital cost. Also the low power output means low efficiency in terms of heat engines.

I have suggested 1 yr or time till next fuel change There is enough heat till that time
Decay heat could be 2-5% of fission heat in this period.


When spent fuel is unloaded, after typically at least 3-4 days of shutdown cooling, it generates around 0.3% of its normal reactor operating power.

So you end up with very little heat, that is quickly decaying away. Not good for power generation.

Meanwhile you're dealing with HUGE source term material. That has already operated in extremely demanding environment. It is "worn out".

Don't put the old timers in a slave labor camp. Let them have their well deserved comfortable retirement bath in a nice warm spent fuel pool.


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PostPosted: Apr 08, 2014 5:56 pm 
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E Ireland wrote:
Which means for the price of reprocessing you could get something like a millenia or more of dry storage.
But then, reprocessing for use in a LFTR should be much cheaper.

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PostPosted: Apr 08, 2014 8:36 pm 
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KitemanSA wrote:
E Ireland wrote:
Which means for the price of reprocessing you could get something like a millenia or more of dry storage.
But then, reprocessing for use in a LFTR should be much cheaper.


Not really - you still require all the expensive parts of a reprocessing plant.
Pyroprocessing might be cheaper but that has yet to be demonstrated on a commercial scale.

Even if you plan to simply fluoridate out the uranium from the spent fuel and burn the rest whole you will still need a huge infrastructure. It is unreasonable to assume you will get the process cost under $1000/kg without some major breakthroughs in reprocessing that have not yet occured.
(FLUOREX appears to have the best chance at the present time, but even that seems doubtful).

Considering that is enough for nearly thirteen centuries of dry storage (even with the conservative assumption that the fund set aside for storage would only just match inflation in dry cask prices) I can't say the economics favour reprocessing.

If you want to start up an LFTR the cheap way to do so involves enriched uranium - attempting handling of spent fuel seems to be a false economy, especially as a lid has been indefinitely placed on the price of uranium by the development of semi practical seawater extraction technologies.


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PostPosted: Apr 09, 2014 12:41 am 
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E Ireland wrote:
KitemanSA wrote:
E Ireland wrote:
Which means for the price of reprocessing you could get something like a millenia or more of dry storage.
But then, reprocessing for use in a LFTR should be much cheaper.


Not really - you still require all the expensive parts of a reprocessing plant.
Pyroprocessing might be cheaper but that has yet to be demonstrated on a commercial scale.
Since when has reaming, fluoridation, fluoride volatility, hydrogenation, and HF electrolysis NOT been done commercially?

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PostPosted: Apr 09, 2014 3:22 am 
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Experience of Yucca should convince everyone of the high cost, including the political cost of direct disposal.
Continued running of fast reactor in Russia, and their progress in new construction should be convincing proof of feasibility of a closed cycle.
Russia, India and China, who together build half of new nuclear construction are proceeding with closed cycle not bothered by any views expressed to the contrary.
file:///C:/Users/sony/Downloads/179693_replacement.pdf
Reprocessing and closed cycle is the future of energy. If you are bothered by near term costs, you could continue to close up nuclear plants and go for cheaper gas. It has started in any case.


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PostPosted: Apr 09, 2014 5:52 am 
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jagdish wrote:
Experience of Yucca should convince everyone of the high cost, including the political cost of direct disposal.

Who said anything about proceeding to a collosal Yucca Mountain style deep geological repository?
All I am proposing is that reprocessing be delayed to be outside at least the century window.
Cheap surface storage is superior in the short to medium term.
jagdish wrote:
Continued running of fast reactor in Russia, and their progress in new construction should be convincing proof of feasibility of a closed cycle.

I never questioned whether a closed cycle is technically feasible - I just question whether its economically worth it given the conditions we now know to exist - that of essentially unlimited cheap(ish) uranium.
jagdish wrote:
Russia, India and China, who together build half of new nuclear construction are proceeding with closed cycle not bothered by any views expressed to the contrary.
file:///C:/Users/sony/Downloads/179693_replacement.pdf
Reprocessing and closed cycle is the future of energy. If you are bothered by near term costs, you could continue to close up nuclear plants and go for cheaper gas. It has started in any case.

Gas is never going to be cheaper in Europe - Shale Gas appears to be a dead duck here - and in any case perhaps I would like to harness the air quality benefits associated with nuclear power and prevent being dependant on Continental Europeans who will cut us off if things ever get serious with the Russians or Algerians?

Saying that near-term reprocessing is not worth the cost is not goign to change the business case of nuclear power.
According to that handy 'Spent Fuel explorer' the radioactivity of spent fuel after 5 years of cooling off is ~685kCi/MT and a gamma power of 780W/MT.
After one dry cask lifetime (100yrs assumed) the fuel will have an activity of 46kCi/MT and a gamma power of just 41.36W/MT.
Those reductions will likely measurably reduce the cost of reprocessing [less money for radiation hardening, increased use of glove boxes etc], but there is little reason to stop there - after two cask lifetimes (so roughly $160/kg for storage) the activity drops again to a mere 9.6kCi/MT and a gamma power of 5W/MT.

After two cask lifetimes more than half the total activity of the spent fuel is derived from 241Am and the various Plutonium isotopes, which seems to indicate that handling the fuel will be considerably less hazardous than the MOX fabrication stage of fuel recycling.

While two cask lifetimes would appear to be a little long for many cases, one cask lifetime seems to have major benefits in terms of removing the very high active short lived fission products from the fuel at almost no cost.
With uranium being cheap at this point and at every concievable point in the future - it seems unlikely that the economics will ever make sense when the price of near-term reprocessing seems to generates a value of $100k+/kg for Plutonium - higher than weapons grade uranium in many cases (with the WGU having a higher fissile content).


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PostPosted: Apr 13, 2014 12:18 am 
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Courts in the US have not accepted the NRC view that site storage is an acceptable management of used fuel. Costs of everything vary and Aluminium, the stuff of Neapolean's extra royal cutlery, is now used for coke cans. Cost of surface storage and mining are on the way up due to local resistance in most cases and the industrial process of chemical processing is likely to go down with Chinese already on the job for their own use.
It may be some time before the Americans wake up to used fuel as an asset. Perhaps the Russians or Chinese may reprocess it for them.


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PostPosted: Apr 13, 2014 8:04 am 
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Uranium mining is largely irrelevant to this question - seawater extraction has now reached $660/kgU.
That is low enough to scotch reprocessing permanently.

And I have yet to come across any significant resistance to onsite storage of nuclear fuel at power plants, certainly not compared to the continuous protests against fuel reprocessing.
Chemical processing has been developed for sixty years and the costs only ever seem to go in one direction - up.

The only reason the Russians can afford to do it is because they have an enormous infrastructure remaining from the Cold War at Mayak and other facilities.


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