"Plucky upstart Brit company Moltex Energy proposes to keep the fuel salt in fairly standard tubes "
Moltex have either moved, or are in the process of moving, to Canada.
Dr Ian Scott of the company said they could not get access to the UK nuclear regulator in the UK.
Basically they've applied high TRL elements to the idea of an MSR to deliver something which is stable by physics, not by having a very reliable control system, while bleeding off the main neutron poisons (like other MSR designs) but locking up the main human poisons, Iodine and Cesium.
IOW it's an MSR designed by adults.
Most amazing factoid? PWR steam turbines are 6-10x the cost of those used in all combustion driven systems (which run at c520 c, rather than the PWR standard of about 312c). The UK AGR designers were right. Targeting the design to match SOP for coal, oil and gas plants was the way to go.
Moltex's goal. Make coal obsolete as a fuel.
I think they might succeed. But not in the UK.