Fission Products: Harnessing Heat to Produce Electricity?

[maxverywell]

Fission products are unstable and generate a lot energy decaying to more stable isotopes. Why we don't use that energy (heat) to produce electricity instead of burying them as nuclear waste?

 

[Astronuc]

Fission products are unstable and generate a lot energy decaying to more stable isotopes. Why we don't use that energy (heat) to produce electricity instead of burying them as nuclear waste?

The heat is of very low quality (low power). A dry storage cask has a surface temperature of about 400 F. There is a thermal shield on some designs that allows the cask to be air cooled. I haven't seen a cask in the field, but colleages tell me that in winter, the snow does not accumulate on the casks. The lids are quite hot - like a normal kitchen oven.

For a reasonable Carnot efficiency - one wants a high temperature - otherwise the energy production rate is too low to cover the capital costs of the equipment.

One interesting possibility would be using the Kalina cycle.

The radiation coming off the spent fuel might be of use - if the fuel was reprocessed.

The spent fuel must be secure! So there are not a lot of options to using it as an energy source after discharge.

 

[minerva]

I'm sure that if you really wanted to, in practice, you could take a cask of radioactive used fuel or vitrified fission product waste and attach it to a Stirling engine or organic-Rankine engine, and use it as a very reliable source of a small amount of power - quite similar to the RTGs used on spacecraft , except with an engine for energy conversion, not thermoelectrics.

But I guess the stringent regulation of radioactive materials, and fear of nuclear technology, makes it economically unfeasible for a relatively small amount of energy.