What is the most promising gen 4 or 5 design?

[kodama]

what is the most promising gen 4 or 5 nuclear reactor design?

i heard bill gates wants to invest in traveling wave reactor.

to limit the field, it has to use uranium, must be economical, must produce very little waste, must be safe, and it can be built with current technology.
built in a nuclear friendly nation (not sure which nations are nuclear power friendly - germany has a moratorium)

or what is your personal preference if you are a nuclear engineer

• 1 Reactor types
  • 1.1 Thermal reactors
    • 1.1.1 Very-high-temperature reactor (VHTR)
    • 1.1.2 Molten-salt reactor (MSR)
    • 1.1.3 Supercritical-water-cooled reactor (SCWR)
  • 1.2 Fast reactors
    • 1.2.1 Gas-cooled fast reactor (GFR)
    • 1.2.2 Sodium-cooled fast reactor (SFR)
    • 1.2.3 Lead-cooled fast reactor (LFR)

• Liquid-core reactor. A closed loop liquid-core nuclear reactor, where the fissile material is molten uranium or uranium solution cooled by a working gas pumped in through holes in the base of the containment vessel.
• Gas-core reactor. A closed loop version of the nuclear lightbulb rocket, where the fissile material is gaseous uranium-hexafluoride contained in a fused silica vessel. A working gas (such as hydrogen) would flow around this vessel and absorb the UV light produced by the reaction. This reactor design could also function as a rocket engine, as featured in Harry Harrison's 1976 science-fiction novel 'Skyfall'. In theory, using UF6 as a working fuel directly (rather than as a stage to one, as is done now) would mean lower processing costs, and very small reactors. In practice, running a reactor at such high power densities would probably produce unmanageable neutron flux, weakening most reactor materials, and therefore as the flux would be similar to that expected in fusion reactors, it would require similar materials to those selected by the International Fusion Materials Irradiation Facility.
  • Gas core EM reactor. As in the gas core reactor, but with photovoltaic arrays converting the UV light directly to electricity.[31]
• Fission fragment reactor
• Hybrid nuclear fusion. Would use the neutrons emitted by fusion to fission a blanket of fertile material, like U-238 or Th-232 and transmutate other reactor's spent nuclear fuel/nuclear waste into relatively more benign isotopes.

 

[etudiant]

It would be helpful if the priorities for the new designs were made explicit, is it increased efficiency, less waste product, greater reliability, lower capital costs or what.
Imho, one overlooked priority is to have the design very easy to operate and essentially idiot proof, somewhat like the TRIGA research reactors. I do not know if it is even possible, but the ideal would be something that has no moving parts.
The experience we have had with Chernobyl and with Julich in Germany ( where the operators mashed jammed fuel spheres into pieces with a broomstick, contaminating the site and the surroundings) suggests strongly that people will find ways to mess up almost anything. So we need designs that minimize the need for human guidance.

 

[DEvens]

It is too soon to pick a favorite. Several of these designs should be tested and research versions built. Several prototypes should be built and run for a few years to find out what the real situation is. No matter how careful you are, the design and the reality are always just a tiny bit different. And there are always things you overlooked or neglected in the design work. There are lots of designs that look great in a computer, then fail pretty savagely when they are built.

I like the idea of getting some kind of breeder working. Whether based on Thorium or Uranium I am not particularly sure. But to get more than 1% of the fuel would be pretty spiffy. It would reduce the waste per kWhr. The waste would be shorter lived, and the longer lived stuff could to some extent be reprocessed and used. It would, one hopes, reduce the net cost of electricity from nuclear. It would make it harder to redirect waste to bomb production, though not impossible. And it would massively extend the time that our nuclear fuel will last.

That should give us ample time to get something really long lasting going. Like fusion. Or space-based solar. Or something really far out that we have only wild-eyed fantasy to go on right now.