Articles techniques et présentations

A Radioisotope Thermoelectric Generator (RTG) is an electrical generator that uses an array of thermocouples to convert the heat released by the decay of a suitable radioactive material into electricity by the Seebeck effect. This type of generator which has no moving parts has been used as a power sources in satellites, space probes, and unmanned remote facilities. Most of RTGs use Plutonium-238 dioxide (PuO2) radionuclides as a heat source. The power conversion efficiency of RTG is limited upto maximum 15% due to lower thermoelement efficiency and high thermal losses in radionuclide enclosures. The heat source is enclosed in a graphite impact shell with carbon bonded carbon fiber sleeve. Recently researchers have published many novel Graphene based composite after discovery of the two dimensional material Graphene; a oneatom-thick, array of carbon atoms is one of the most promising materials. This graphene based composite has superior mechanical and thermal properties compared to graphite & carbon
bonded carbon fiber sleeve. This study deals with the replacement of the existing graphite impact shell and carbon bonded carbon fiber sleeve with Graphene based composite. The performance has been evaluated using COMSOL Multiphysics® software. The paper describes the practical feasibility study on replacement of Graphene based composite with respect to graphite impact shell used as a radionuclide heat source enclosure and carbon bonded carbon fiber sleeve. 
Also it has been evaluated the increase of overall efficiency using Graphene composite in
contrast to the existing graphite impact shell under equivalent temperature gradient & surface area of the heat source. Due to higher efficiency, this technique may open up an opportunity for the use of alternative low cost radioisotopes like Americium-241, which is present in high level radioactive liquid waste. This not only will replace rarely available plutonium-238 from today’s RTGs without compromising the power output and overall weight, but also will realise the strategy of “wealth from waste”.

Keywords: Radioisotope Thermoelectric Generator (RTG), Graphene composite, Graphene, Carbon bonded carbon fiber sleeve, Graphite impact shell