KitemanSA wrote:

I was thinking more like, twice the volume of salt at $X/in3 vs. one unit plus cost of extract holdout system (both of which have been shown to result in the same breeding ratio with the optimal %age of U232....what, you mean they haven't... then modify the designs...). You know, THAT kind of design optimization routine, with numbers. :shock:

The cost of the NaF/ThF4 eutectic is low enough that it doesn´t matter. I didn´t do the sort of optimization that you had in mind, but was simply pointing out the other advantages of going for a bigger blanket.

But, doing a quick check, 400 cubic meters blanket salt/GWe, 22.5% ThF4, this is 90 cubic meters ThF4. At a density of ThF4 of around 5 or 6, let´s take 6, this is 540 tonnes ThF4 containing 407 tonnes Th. At $100-kg high purity Th it is $41 million. Chump change for a multi billion dollar powerplant. Prices will likely be much lower once a big market is established. Cost of NaF is at least one order of magnitude lower, feel free to ignore this.

Now, you might be able to build a still for less than $41 million. And you could save a bit off the vessel cost as well. But you won´t get the thermal storage benefit, and have to bother with large ThF4 additions with an operating reactor...