Alternative isotopes in RTGs? -Reply

[Charles Willis <CAW@nrc.gov>]

Don, 

As you can imagine, quite a number of nuclides have been seriously considered and
several have been used in RTGs.  Considerations include cost of production, power
density, shielding requirements, half  life and safety.   Back when I was involved in
these issues, U-232 looked attractive, despite having to deal with a number of
daughter products, but the feasibility  of production in the quantities needed had
not been fully demonstrated.  Every nuclide presents problems of one sort or
anoth.  Pu-238 consistantly has come out on top for a variety of applications.  Be
assured that people keep looking for something better, but it is not new ground.

Do you suppose that the critics would have been less critical if the fuel had been
U-232?  I have my doubts.

Charlie Willis
caw@nrc.gov