Energy From Thorium Discussion Forum

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PostPosted: Oct 15, 2014 9:09 am 
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file:///C:/Users/sony/Downloads/15-3023_Ehud%20Greenspan.pdf


if it works, it could burn the used fuel or be a thorium fuelled solid fuel system, a variation of BWR.


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PostPosted: Oct 15, 2014 9:50 am 
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I have been talking about this, in combination with ESBWR, for quite some time. 8)


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PostPosted: Oct 15, 2014 9:55 am 
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do you have a proper link, or upload of the file? That's pointing to your C drive.


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PostPosted: Oct 15, 2014 10:15 am 
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I think it' s this : Self-Sustaining Thorium Boiling Water Reactors. It didn' t impress me much...


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PostPosted: Oct 15, 2014 10:22 am 
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The RBWR is a subset of the wider Reduced Moderation Water Reactor that the Japanese have been working on for years.


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PostPosted: Oct 15, 2014 2:16 pm 
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The U/Pu version already achieves regeneration and negative void coefficient with well known MOX fuel.
I don't really see the need for thorium here.


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PostPosted: Oct 17, 2014 5:27 am 
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The existing MOX fuel concept goes only a short distance towards enhancing the power from the uranium mined. For still more power making fuller use of uranium you need more. Fast spectrum is one way. Reduced moderation also goes further than the MOX in current thermal reactors. Using thorium in combination with enriched uranium/recovered plutonium is an improved scheme in thermal reactors. A combination of both would be interesting.


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PostPosted: Oct 17, 2014 8:32 am 
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Quote:
The existing MOX fuel concept goes only a short distance towards enhancing the power from the uranium mined. For still more power making fuller use of uranium you need more. Fast spectrum is one way.


The U/Pu version is discussed in the link posted by E Ireland (Reduced Moderation Water Reactor). This version already achieves iso-breeding (what I called "regeneration") without Thorium. And it uses MOX (mix of oxides : UO2, PuO2, ThO2, ..., here I talked about (UO2, PuO2)) with an higher content of PuO2 than the MOX used in classic LWRs (more like the MOX used in Fast Breeder Reactors). Or I completely missed something.

If using thorium permits to increase the liquid-water-to-fuel ratio ( because there is very little volume for water in their core, but I don't know if it's a problem for safety since boiling is very efficient to transfer heat ) maybe it worths it.

Their core is very large (7.6 meters for diameter) and their vessel has an inner diameter of 8.9 meters which is bigger than the ABWR's vessel diameter (7.1 meters for inner diameter). If using thorium permits to diminish the diameter of the core it will be good for the fabrication of the vessel.

Otherwise reprocessing of (PuO2, UO2) fuel is well more mastered than (ThO2, UO2) fuel, if I'm not mistaken.

By the way, it must be difficult to prove that we can insure criticallity control in a big accident with a fast reactor in an environment full of water. Having the control rods inserted by the bottom of the vessel is an advantage here.


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PostPosted: Oct 17, 2014 9:04 am 
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In more recent studies they appear confident they can make a refitable drop in core for the ABWR


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PostPosted: Oct 17, 2014 9:38 am 
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In more recent studies they appear confident they can make a refitable drop in core for the ABWR


You mean that they can use the ABWR's vessel while conserving the same power and iso-breeding ? And they use thorium ?


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PostPosted: Oct 17, 2014 10:46 am 
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fab wrote:
Quote:
In more recent studies they appear confident they can make a refitable drop in core for the ABWR


You mean that they can use the ABWR's vessel while conserving the same power and iso-breeding ? And they use thorium ?


They can do the isobreeding and same power in teh ABWR vessel using Pu/U and apparently the U/Th cycle.
There has even been work on using nitride fuels to allow for a more negative void coefficient.


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PostPosted: Oct 17, 2014 10:57 am 
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Isobreeding has been demonstrated already, in the last core of the Shippingport reactor.

This RBWR concept requires a lot of reprocessing of thoria fuel which is very expensive but it may further the use of thorium fuel as a concept.


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PostPosted: Oct 17, 2014 11:37 am 
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More importantly, it allows us to commence build out of a proven design right now (ABWR, although ESBWR should work as diameters are similar and an RBWR core is even more pancake-like than the standard ESBWR core) and then switch to a closed cycle as and when required with midlife conversions.


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PostPosted: Oct 17, 2014 1:12 pm 
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Quote:
They can do the isobreeding and same power in teh ABWR vessel using Pu/U and apparently the U/Th cycle.
There has even been work on using nitride fuels to allow for a more negative void coefficient.


Thanks for the response.

Quote:
More importantly, it allows us to commence build out of a proven design right now (ABWR, although ESBWR should work as diameters are similar and an RBWR core is even more pancake-like than the standard ESBWR core) and then switch to a closed cycle as and when required with midlife conversions.


Yes, if we can use this in an ESBWR it is very good (or a Kerena design, the vessel has the same diameter than ESBWR and ABWR) and the ESBWR is already licensed but they will have to license the version with the new core. This seems a far better way to isobreeding than Sodium Fast Reactors. However the conceptors should prove that they will be able to control criticality in a big accident scenario (with all this water around this may be difficult, but here the control rods are under the core, that's good).

Quote:
This RBWR concept requires a lot of reprocessing of thoria fuel which is very expensive but it may further the use of thorium fuel as a concept.


If they can do isobreeding with the U/Pu cycle that's better. The burnup with the U/Pu version is 50 GWd/t which is similar to current LWRs, it's maybe no too bad economically. But they will have to reprocess a lot more Pu than current recycling. On the other hand they don't need natural uranium and enrichment.


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PostPosted: Oct 17, 2014 4:15 pm 
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RMWR likely won't work with natural circulation designs such as ESBWR, because of the much higher pressure drop cores employed in RMWRs. Need to push out all that moderator results in tight fuel pitch. It should work well with forced circulation Kerena reactor. But if the goal is to prove the concept in a modified BWR then ABWR looks the best candidate.


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