There are many different thorium designs based on different objectives. The original designs assumed that we would run out of uranium so the primary objective was breeding. It is clear now that we have much more uranium than they thought.
We should start with an understanding of how much waste is there currently from today's reactors. Roughly one coke can would hold all the waste generated from one person's electricity (European standards roughly 1kW) for a lifetime.
We can reduce the volume of waste readily by removing the uranium and re-enriching it. This can be done with virtually all reactors including todays reactors. This will remove 90% of the waste volume but does nothing to reduce the hazards of the waste.
We can remove the elements that are heavier than uranium (transuranics or TRUs). This is the long term hazard. This material can be recycled into a reactor to be fissioned (destroyed forever not simply buried). This can be done to a very limited extent in some of today's reactors. But either IFR or molten salt reactors would really be the appropriate way to eliminate the long term hazards of nuclear waste. Such a process will be limited by our ability to separate the TRUs from the fission products. We expect to achieve around 99% separation so to reduce the long term hazard 100 fold.
The near term hazard comes from the fission products. These will decay in a reasonable time. Every 30 years the radioactivity will decay by half. So by 300 years you are back to roughly background radiation. 300 years is short enough we know how to build containers to last that long.
We should start with an understanding of how much waste is there currently from today's reactors. Roughly one coke can would hold all the waste generated from one person's electricity (European standards roughly 1kW) for a lifetime. We can reduce the volume of waste readily by removing the uranium and re-enriching it. This can be done with virtually all reactors including todays reactors. This will remove 90% of the waste volume but does nothing to reduce the hazards of the waste.
We can remove the elements that are heavier than uranium (transuranics or TRUs). This is the long term hazard. This material can be recycled into a reactor to be fissioned (destroyed forever not simply buried). This can be done to a very limited extent in some of today's reactors. But either IFR or molten salt reactors would really be the appropriate way to eliminate the long term hazards of nuclear waste. Such a process will be limited by our ability to separate the TRUs from the fission products. We expect to achieve around 99% separation so to reduce the long term hazard 100 fold.
The near term hazard comes from the fission products. These will decay in a reasonable time. Every 30 years the radioactivity will decay by half. So by 300 years you are back to roughly background radiation. 300 years is short enough we know how to build containers to last that long.