Energy From Thorium Discussion Forum

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PostPosted: Aug 10, 2013 9:53 am 
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Cyril R wrote:
One advantage with a fully submerged primary loop is inherent pressure suppression: there is no longer a need for pressurized containment. Not even a drywell/wetwell structure, so is simpler than BWR containments.


This reminds me of the Japanese KAMADO FBR (see attachment), although the primary loop is CO2. The idea of the KAMADO is also to reuse RPVs of LWRs.


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PostPosted: Aug 11, 2013 2:41 am 
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camiel wrote:
Cyril R wrote:
One advantage with a fully submerged primary loop is inherent pressure suppression: there is no longer a need for pressurized containment. Not even a drywell/wetwell structure, so is simpler than BWR containments.


This reminds me of the Japanese KAMADO FBR (see attachment), although the primary loop is CO2. The idea of the KAMADO is also to reuse RPVs of LWRs.


But this is a fast reactor! Seems difficult to avoid certain reactivity accidents with all that water that isn't supposed to be in the core as a liquid during normal operation.


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PostPosted: Aug 13, 2013 1:05 pm 
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Candu is a pressurized heavy water reactor. A light water version would be a pressurized water reactor. The half meter bundles are a good idea which should be retained. You have to work out the enrichment required.
There are several other possibilities.
a. You could keep a heavy water moderator (at low pressure) and use light water coolant. It has been tried out in Canada.
b. You could use heavy water moderator but a coolant with lower vapor pressure. One possibility is a perfluorocarbon like the lubricant Krytox. This will reduce the pressure rating and cost of the pressure tubes. Molten salts/metals could also be used.
http://www2.dupont.com/Lubricants/en_US ... Guide.html
c. Thorium based fuels (solid) could be used to concurrently create U-233, to be separated out when reprocessing and the LFTR come into use.


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PostPosted: Aug 13, 2013 4:19 pm 
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Here is a nice, detailed overview of various HW-moderated reactors, including light water, gas, organic and even Na cooled types.
From a former colleague in AECL, Chalk River.

https://dl.dropboxusercontent.com/u/11686324/Blair_Bromley_20110204.pdf


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PostPosted: Aug 15, 2013 4:36 pm 
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I haven't read much of the thread but I don't think anyone pointed out that several MIT profs spent several years promoting a light water version of CANDU back in the 1990s. Filling light water completely between pressure tubes would be way too much water (way over moderated) so if I recall, the idea was simply another low pressure pipe around each pressure tube that would have the thin layer of calandria water needed. There are likely many open source papers you can find, the link below is for their major report/book on the subject but I don't think it is open to the general public.

http://dspace.mit.edu/handle/1721.1/67640

David LeBlanc


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PostPosted: Aug 16, 2013 4:03 am 
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Thanks for pointing that out David. Here's one web find that is available publicly:

http://www.osti.gov/bridge/servlets/pur ... 402402.pdf

appears to be something of a summary of the work.

The idea is interesting, but not as passively safe as a pool type reactor of this design. They could solve the water space problem with a plenum and tubesheet approach and vertical orientation, offline refuelling.


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PostPosted: Aug 17, 2013 12:48 am 
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Has anyone considered moderator tubes of Beryllium metal or oxide, cooled with boiling water? The tubes would be thick to meet moderation requirements and could be shaped on outside to design right gap for coolant.
Alternately it could be a cylindrical block of solid moderator with perforations for fuel and coolant channels. Graphite block reactors are in use but BeO would be fire resistant and more dimensionally stable..


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PostPosted: Aug 17, 2013 12:52 am 
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Has anyone considered moderator tubes of Beryllium metal or oxide, cooled with boiling water? The tubes would be thick to meet moderation requirements and could be shaped on outside to design right gap for coolant.
Alternately it could be a cylindrical block of solid moderator with perforations for fuel and coolant channels. Graphite block reactors are in use but BeO would be fire resistant and more dimensionally stable.
BeO blocks could be lined with salt resistant material like SiC and used with molten salt too.


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PostPosted: Aug 17, 2013 4:09 am 
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Has anyone considered moderator tubes of Beryllium metal or oxide, cooled with boiling water? The tubes would be thick to meet moderation requirements and could be shaped on outside to design right gap for coolant.
Alternately it could be a cylindrical block of solid moderator with perforations for fuel and coolant channels. Graphite block reactors are in use but BeO would be fire resistant and more dimensionally stable.
BeO blocks could be lined with salt resistant material like SiC and used with molten salt too.


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