Follow up question to "For the Greens"

[sd_matt]

Quick background: A couple pages in and my layman self was asking about the Elysium Molten Salt Reactor concept.

I forgot to cut to the chase by asking what you all think a MSR fleet would look like. The goals would be to 1. Close the fuel cycle. 2. "Burn up" our waste fuel.

What configuration(s) would you employ? What would be your development path? For example I think the Elysium concept would be a relatively easy way to develop and prove the feasability of the MSR. Of course if I was in charge I would concurrently develop Alvin Weinbergs original thorium configuration and boost support to fusion dark horse concepts like Polywell ect.

[KitemanSA]

IMHO, the goal of “burning up the waste fuel” is bound to be counter-productive. Assuming you think that fast reactors are the way to do it, the very small number of fast reactors that can be made, and the very slow core doubling time means we will still be working on SNF for many 1000s of years. It is far better to use fast reactors to breed U233 and use that to start up thermal spectrum breeders. The Th232/U233 cycle can then grow at a much faster rate, and that is the closed cycle you mentioned.

So, Path forward…

* Build out as many Pu based fast reactors as we have Pu to fuel (sadly very few). I would investigate the trade-off between Elysium’s big pot design and a stainless steel plate HEX core design where the fuel salt (Pu/U238 based) does NOT circulate except for processing. The blanket salt (Th based) would be the coolant salt and would be circulated as fast as needed the match demand. I think this would allow us to build more units off the bat.
* Use all breeding potential in said reactors (in excess of sustainment) to breed U233.
* Use graphite plate HEX style thermal spectrum reactors to sustain/breed for more reactors.

I estimated that after ~25 years, the GPHEX reactors would outbreed the fast reactors. From that point on, continuing to run the fast reactors was counter productive. You breed as much Pu as you burn and you also breed other nasty higher actinides. All you burn is fairly innocuous U238.

[sd_matt]

What does SNF mean?

As for our waste fuel rods do you see any paracical use whatsoever in a MSR of any type?

[KitemanSA]

“Spent Nuclear Fuel”

It is the legal term for the fuel rods that have too much fission products to retain reactivity. There is still ~97% UNSPENT fuel in them, but the legislation the was supposed to “solve” the waste problem just made it 100 times worse. It is illegal for the power plants that generated the SNF to do anything but store it because… they no longer own it. The FedGov owns it.

[KitemanSA]

As for our waste fuel rods do you see any paracical use whatsoever in a MSR of any type?

As I said, all the available Pu, including that in SNF, should be used to start up fast breeders for U233 production. In this case I mean something like the molten chloride salt fast breeder proposed by Elysium, but maybe with a different core design. It won’t “burn up” our stockpile since the fast breeders will be breeding as much as they consume.

Now, once we have enough THERMAL spectrum breeders going to take care of our needs, it would then be possible to slowly convert the fast breeder from the U/Pu cycle to the Th/U cycle, thereby burning off the Pu, but it reduces the efficacy of the fast breeder to breed excess U233.

[KitemanSA]

I keep forgetting this is the Polywell Forum. Perhaps you can get your question answered better at the “Energy from Thorium Forum”.

http://energyfromthorium.com/forum/sear ... be6a21b46a

Hope the link works.