Energy From Thorium Discussion Forum

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PostPosted: Apr 20, 2015 7:20 pm 
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alexterrell wrote:
Right - so Xenon and a bit else out, as enriched as possible/allowed Uranium in. Fresh Thorium in as well?

After 30 years it's clogged up with other fission products and 240 and 242Pu.

The thorium inventory is added at startup.
The only addition will be enriched uranium and potentially some of the diluent salt.


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PostPosted: Apr 23, 2015 10:36 am 
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Well if you trade off a bit more neutron economy (you still come out far ahead of the LWR in terms of uranium consumption) you can go for a 60-year fuel salt life.

Which seriously reduces the amount of plutonium and heavier actinides that make it out of the reactor.
Most of the 241Am production is avoided as the 241Pu gets burned as it gets formed in the reactor and there is very little (proportionately) around at any one time.

You can then fluorinate to pull out the (still enriched) uranium and the neptunium, then use a lead glass-making process to convert the rest directly into an appropriate glass form.
If you use my preferred salt, NaRb, you can use the salt itself as a large part of the glass matrix and reduce the wast efraction substantially.


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PostPosted: Apr 24, 2015 9:29 am 
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Right now there are two problems holding up the nuclear technology in old user countries of W Europe and N America.
Stocks of used LWR fuel.
Comparative economy of gas (in US only).
For an acceptable way out, you may be required to
Use FNaBe as carrier salt.
Use water as moderator. You could run it in tubes like a boiler to keep it away from fuel salt.
Terrestrial Energy are close but are still using low life graphite to make it low pressure. Thorium as part of fertile may be useful due to superior fissile 233U created by irradiation.


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PostPosted: Jul 19, 2015 4:58 am 
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Reprocessing of used fuel is getting back on agenda
http://www.washingtontimes.com/news/201 ... p-fuel-in/
Naval fuel will give much more fissile for burning thorium than the commercial reactor fuel. It could get a burner LFTR going. On one hand it will help burn the transuranics with thorium and on the other hand use the HEU blended to 20% for similar use. Just use easily available salts and produce with a generation of burner reactors. The breeders can be the next generation using the 233U produced in the first thorium generation.


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PostPosted: Jul 19, 2015 3:38 pm 
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This is a good thing. A new facility built by government money will allow new technologies to enter the nuclear realm. The control systems of today are very much changed from the 1950s and 1960s technology of some of the stuff in Idaho (and Hanford). I'm sure the advancements in other technologies can also be applied. It might even be a fun place to work.


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PostPosted: Jul 23, 2015 5:48 am 
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Thorium based LWR is already known. It could be tuned to a regular reactor system.
Initial supplies of 233U can be obtained by using a Th Pu M O X as Norvegians are trying out.


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PostPosted: Sep 08, 2016 4:51 pm 
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My take on all of this starts with a few benchmarks. Firstly you have to match the light water reactor on technical terms in order to even be in the game. Then you have to beat fossil fuel power plants on price. Some considerations might be listed as follows:-

1. On safety is your design no worse than a LWR.
2. On nuclear waste is your design no worst than a LWR.
3. Does your design deliver energy significantly cheaper than fossil fuels.
4. Can you get to market quickly.

That is the primary benchmark against which I would judge a reactor design. There are other wonderful benefits that can be had from Thorium and molten salt designs. However they are cream on the cake as far as I'm concerned. If they compromise on any of the items above I'd say they are probably misguided.

Being much better than the LWR on safety and waste tells a good story. And it's a good thing. But IMHO it won't influence the bulk of the public much. Most will either not care either way or else they will demand impossible perfection which you can't achieve anyway.

If forced to only improve safety or only improve waste I'd go with safety. I think the safety story bothers people more than the waste story.

Is my list the right list? Of course it's ultimately for regulators, investors and utility customers to judge. I'm not an investor. I'd like to be an investor but the option does not seem to be there. And I'm not either of the other two.


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PostPosted: Sep 10, 2016 4:40 pm 
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Cyril R wrote:
Kirk Sorensen wrote:
Two-fluid thorium reactors have a much easier time keeping neutron flux off the reactor vessel wall.


Not really an advantage, it is a disadvantage. You're throwing out a non-problem (all reactors manage this today) for a very serious barrier fluence issue. You cut reactor vessel fluence from a 1-2% or so value to 0.1% but in return you have a two fluid barrier vessel which has to take 50% of the core flux. That's one step forward, ten steps back.
I suspect Kirk's response would be that since the inter-fluid barrier is the graphite moderator which already takes the fluence it is thus not an issue.

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