Mercury and Radioisotope Thermalelectric Generators Country:
United States Date: Spring 2010 Why was mercury used in some
radioisotope thermalelectric generators (RTGs)? After some
extensive searching, I was unable to find a single reference to
the use of mercury in a Radioisotope Thermoelectic Generator. Do
you have any concrete examples of this? The only use for mercury
I can imagine, is to act as a circulating cooling fluid. The
metal mercury was used in a Rankine cycle generator on the
SNAP-1 RTG to make electric power. It was never deployed. Later
RTG's seem to have used thermoelectric methods to generate the
electricity. The Rankine system is similar to a steam power
plant, but mercury metal is used instead of water. Mercury was
found to be the best working fluid under the conditions and
temperatures that space RTG systems operate. NASA tech note TN
D-5092 has useful information how to make a mercury boiler for
use in space. Nuclear reactors have also been used to generate
power in space using a mercury