I recently learned about traveling wave reactors (TWRs) on the Netflix Bill Gates special, as an example of a cutting-edge technology Gates is funding which has the potential solve several environmental problems.
The TWR is a nuclear fission reactor which sounds a bit too good to be true (via Wikipedia):
- Uses spent fuel from other fission reactors, meaning it doesn't require mining of new uranium
- Consumes the spent fuel from these reactors, meaning it could be used to dispose of this nuclear waste
- Doesn't produce any of its own toxic byproducts
- Can run in containment for decades, with no need to add/remove fuel, reducing operational costs and risk to operators
So, what gives? Why don't these exist yet? The Wikipedia article (and the Netflix special) mention some political challenges that have delayed construction of a demonstration reactor, but I wasn't able to find any additional detail on technical challenges.
Like fusion reactors (which have both political and financial support, and never seem to get any closer to existing), I assume there must be some specific, unsolved technical challenges.