Supercritical CO2 Recompression Cycle for Nuclear Reactors

[Rennhack]

This is old news, but it is new to me.  I figure it will give us something to talk about other than Navy Nukes, PoliSci, or Karma for 5 min.

http://nextbigfuture.com/2009/06/supercritical-co2-recompression-cycle.html
http://nuclear.inl.gov/deliverables/docs/interim_report_300mwe_s_co2.pdf
http://www.ne.anl.gov/facilities/co2loop/
http://dspace.mit.edu/bitstream/handle/1721.1/17746/56504009.pdf


Skinny:  This high performance design achieves a thermal efficiency approaching 53%, which yields additional cost savings. [Current nuclear reactors are at about 35% thermal efficiency, and some newer designs will have 40-45%]

And the supercritical CO2 turbines are tiny:

[BetaAnt]

This passes the OOOHHH-AAAHHH test but, other considerations are not discussed. 

Fuel cycle and waste management (what are the isotopic and radiological dynamics?) and reactor design are not discussed (550C and using U233 or Thorium). I would like to see a workable prototype first. Otherwise the design reminds me of an HTGR without a moderator/reflector (the proposed size is so small that neutron propagation will leak out). The neutron cross section of CO2 has to be incredibly small.

Using Thorium would lend to a fast flux reactor (neutron embrittlement anyone). The compressor and generator are sealed into the vessel housing. Synthetic lubricating products tend to break down rapidly in a high flux environment. Looks good on paper and you can build a nice model but the starship Enterprise is a long way from her first voyage.

And, the best for last, sell the name "Supercritical" CO2 gas reactor to the NIMBYs. They would have a cow and a media field day with the name and the process. 

As for the design, its like new cars vs old cars. I can rebuild a carburetor or engine, gap plugs, and change out points and condensers but I sure as hell cannot figure out the new sensor and computer technology of today's cars. 

Nice discussion but will anyone byte? 

BA 

[HydroDave63]

Except that this super-small red gizmo hasn't been prototyped and proven, it's only theory. One could also do a theory run using a Tesla turbine and selected triple-point fluids and come up with good numbers.

From the nextbigfuture text:

The basic design achieves 45.3 % thermal efficiency and reduces the cost of the power plant by ~ 18% compared to a conventional Rankine steam cycle. The capital cost of the basic design compared to a helium Brayton cycle is about the same, but the supercritical COB2B cycle operates at significantly lower temperature. (In a reactor, that CO₂ will undergo neutron activation much more than helium) The thermal efficiency of the advanced design is close to 50% and the reactor system with the direct supercritical COB2B cycle is ~ 24% less expensive than the steam indirect cycle and 7% less expensive than a helium direct Brayton cycle.  It is expected in the future that high temperature materials will become available and a high performance design with turbine inlet temperatures of 700P o PC will be possible. This high performance design achieves a thermal efficiency approaching 53%, which yields additional cost savings. [Current nuclear reactors are at about 35% thermal efficiency, and some newer designs will have 40-45%] emphasis by Dave

[BetaAnt]

Using geologically deposited thermocouples has also been proposed (geothermal energy). Safe and green. Why not use that?

BA