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PostPosted: Oct 13, 2015 4:46 am 
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It seems Westinghouse wants to stay in the reactor business:

http://atomicpowerreview.blogspot.com.a ... -fast.html

However, I'm not sure I agree with their choice of design - I'd previously dismissed lead-cooled, but it does have some advantages.

Will this lead to the other big Gen III reactor vendors attempting to get some Gen IV offerings?


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PostPosted: Oct 13, 2015 7:52 am 
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It is very interesting to see a big company in this domain.

Quote:
The Westinghouse LFR project is intended to meet all the Gen-IV stipulations for overall design mentioned above, but also will be exceedingly safe and highly economical to build and operate. She described the "Gen V" label as a target out in time at which this project is directed.


They are optimistic, I wonder what materials they will use and what is their accident tolerant fuel.


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PostPosted: Oct 13, 2015 11:57 am 
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fab wrote:
It is very interesting to see a big company in this domain.

Quote:
The Westinghouse LFR project is intended to meet all the Gen-IV stipulations for overall design mentioned above, but also will be exceedingly safe and highly economical to build and operate. She described the "Gen V" label as a target out in time at which this project is directed.


They are optimistic, I wonder what materials they will use and what is their accident tolerant fuel.


I'd be interested in that as well. Most of the work on lead cooled reactors has focused on metallic materials, typically with oxygen or oxygen-forming impurities added deliberately to the lead to form the protective oxide layers for lead dissolution resistance.

However, from my own research I'm very confident that silicon carbide as well as carbon composites are fully compatible (inert) with molten lead. If so, the same accident tolerant triplex SiC composite cladding developed for LWRs, should also be applicable to LFRs...


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PostPosted: Oct 13, 2015 12:36 pm 
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Quote:
Most of the work on lead cooled reactors has focused on metallic materials, typically with oxygen or oxygen-forming impurities added deliberately to the lead to form the protective oxide layers for lead dissolution resistance.


They spoke about economic hydrogen production, I guess that they speak about thermochemical processes. They need at least 570 °C in the core to do that (for example copper-chlorine cycle). Will the oxygen dissolution method be sufficient to preclude corrosion ?

It is a fast reactor. I guess that they want to recycle the fuel, I wonder how this impacts the economics (they said the concept is very economically competitive).


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PostPosted: Oct 13, 2015 10:38 pm 
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Perhaps they are looking for economics of scale with factory assembled modular cores that could be filled with lead, allowed to freeze and shipped?


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PostPosted: Oct 14, 2015 2:10 am 
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Lead cooled reactors are safe from sodium fires, the main bug in fast reactors. If they solve the problem of corrosion due to molten lead, they are on to next stage in sustainability of nuclear power. As fast reactor, fissile problem is solved in blankets. Used fuel is less and recycled. It may overcome the fire phobia of sodium cooled fast reactors.


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PostPosted: Oct 14, 2015 5:22 am 
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Cyril R wrote:
fab wrote:
It is very interesting to see a big company in this domain.

Quote:
The Westinghouse LFR project is intended to meet all the Gen-IV stipulations for overall design mentioned above, but also will be exceedingly safe and highly economical to build and operate. She described the "Gen V" label as a target out in time at which this project is directed.


They are optimistic, I wonder what materials they will use and what is their accident tolerant fuel.


I'd be interested in that as well. Most of the work on lead cooled reactors has focused on metallic materials, typically with oxygen or oxygen-forming impurities added deliberately to the lead to form the protective oxide layers for lead dissolution resistance.

However, from my own research I'm very confident that silicon carbide as well as carbon composites are fully compatible (inert) with molten lead. If so, the same accident tolerant triplex SiC composite cladding developed for LWRs, should also be applicable to LFRs...


Wouldn't some form of pebble bed configuration work and be cheaper. SiC clad pebbles sitting in lead. That would allow over 1000C in the lead bath and hence reduction of sulphuric acid to make hydrogen. Possibly some way of adding pebbles in at one end and removing them at the other.

Liquid fuels are easier though!


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PostPosted: Oct 14, 2015 9:47 am 
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Pebblebed wouldn't really work in molten lead - it would be too difficult to get them to sink in it.


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PostPosted: Oct 14, 2015 1:03 pm 
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As I recall, they float upwards in Per Peterson's pebble bed MSR design. Why not in lead too?


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PostPosted: Oct 14, 2015 8:25 pm 
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Lead has much lower neutron absorption than sodium, especially if most of it is 208Pb. This means you can have wider channels between the fuel elements, which reduces back pressure, making pumping easier and allowing natural circulation in loss of power accidents. Pebble fuel would cause much more resistance to the coolant flow than vertical fuel rods. Thermal reactors need to have about ninety percent of the volume of the core as moderator, if graphite or pyrolitic carbon is used, so pebbles make sense, but a fast reactor can be designed without such constraints.


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PostPosted: Oct 15, 2015 9:21 am 
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Best keep high pressures outside the reactor core. Water in fast reactors is desireable only as secondary or tertiary coolant.


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PostPosted: Oct 18, 2015 3:24 am 
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Fast reactors have the USP of burning LWR used fuel, or waste, as it is called. The best waste burners are Molten Chloride Fast Reactors.
Chloride/pyro processing also provides synergy with MCFR's.
Perhaps they should go to MCFR.


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