Problem with the molten salt reactors at this time is FLiBe purity..I don't know a heck of a lot about the molten salt reactors but most seem to be leaning towards FLiBe as the coolant. Purity in terms of general purity but also the isotopic purity of the Lithium. It needs to be 99.995+% Li-7 as Li-6 is a neutron absorber. That is a tremendous purity level to achieve.
The problem is a combo of a few things...at least for the US (and most other countries):
1) Past process in the US used partioning into liquid mercury. Yes mercury. That site is one horrendous mess and the process is outlawed.
2) that process was never really used to reach that isotopic purity so there are no stockpiles of material (mercury process can only reach 99.9%)
3) the process is government controlled as the real reason for Li enrichment is for the Li-6 which is used in triggers for nuclear weapons.
4) the US government and other governments no longer actively enriches lithium and they have NO interest in doing so again.
5)Li-6 is the byproduct and of course a defense controlled item. Logistical hell.
There are believed to be 2 lithium enrichment facilities in the world that use the mercury process. YOu can't get to the purity and it's hard to argue the technology is green as long as the Li is coming from the mercury process. Lots of work still to be done for the molten salt reactors that we will continue to see the PWRs being built for the foreseeable future.
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