[adamcanady]

To get this straight, when they indicate 96% utilization of the uranium, they don't mean converting 96% of the total energy to electricity, as it is assumed that some will be lost along the way, right?

If the above statement is true, what happens to the remaining 4% of the energy in the uranium? Is it just not effective to have it in the molten salt, so the entire batch is replaced? Or does this happen 'on the fly' so to speak?

[throwaway_yy2Di]

It means 96% of the uranium fuel undergoes fission (gets its nuclear potential energy converted to heat). When they separate out fission products (waste) by chemical processing, about 4% of the fuel gets dragged into the waste stream. It looks like a cost/benefit decision not to recover it:

    Of the 200 kilogram lanthanide mass removed by liquid metal
    extraction, we estimate that approximately 20 kilograms will
    be actinide contaminant with a longer half-life similar to
    SNF. It may be most practical to leave such a small quantity
    embedded in the ceramic granules, as it would be well
    distributed and would not materially extend the time for the
    overall waste form to reach background levels. If desired,
    however, the actinides can be further separated offsite with
    additional post-processing techniques.

[pdf] http://www.transatomicpower.com/wp-content/uploads/2015/04/t...

The mass flow is 500 kg/year fuel in, and 500 kg/year waste out -- of which, 20 kg (4%) is unrecovered actinide fuel.

[simcop2387]

I think it means that they'll be using up 96% of the uranium but the 4% is unusable with this method. That the concentration is down low enough that they're unable to extract energy from it at that point.

[alexhill]

96% of fissile material converted to non-fissile material, and that energy is then converted to electricity at normal steam turbine efficiency, 30% or something. This as opposed to less than 1% for Gen III reactors.

Edit: I posted that fuel handling is a batch process, not continuous – that might not be true for molten salt, not sure.

[JoshTriplett]

> that energy is then converted to electricity at normal steam turbine efficiency, 30% or something

It amazes me that we don't have a better way to use the power generated by nuclear fission or fusion than heating water.

[Turing_Machine]

Steam is actually a pretty good working fluid, although the fact that we have 200 years of experience with it undoubtedly plays a significant role.