Reply To: turn heat into electricity

[delt0r]

The huge advantage of homogeneous reactor design, That is designs where the fuel is mixed with the coolant is that it is very easy to avoid hot spots, keep reactivity predicable and even, and maintain a positive void coefficient and a negative temperature coefficient. You also get perfect even burn for free. These things are all hard to achive with solid fuel designs and tyically require a fairly compilcated fueling schedule for even burn at least. These things are all even harder to achieve with fast reactors.

For thermal designs with water and dissolved salts they have the lowest fuel inventory required by a long shot, and for fast reactors they are one of the surest ways to maintain stable reactivities with passive control. Other practical issues is you don’t need to validate fuel element design which is still a very large cost (time as much as money). Then there is a few unvalidated at this point ideas, of continuous in situ processing, which add a lot of other advantages to the complete fuel cycle. Also this can reduce the decay heat quite a bit too since thing don’t accumulate and some wastes can be pulled out when a more favorable isotope is produced. Further you can degauss it and keep out neutron poisons especially Xe which makes the designs capable of load following, or more importantly easier to make load following… ie capable of peek power production.

On planet earth keeping water out is a exercise in futility when the unexpected happens. Say like a giant wave of … Water! Note that the water in air can set liquid Na on fire. The problem is that we either have salts that are not stable with water when molten, or tend to be soluble in water when not (Chlorides). As for liquid metal designs i can’t see what we gain with Na that something like lead/Bismuth doesn’t give us? Add that the later can have enough heat capacity to passively deal with decay heat.