Energy Technology and Advanced Materials› Nuclear Energy: Fission, Fusion and Thorium
With reference to radioisotope thermoelectric generators (RTGs), consider the following statements:
- 1. RTGs are miniature fission reactors.
- 2. RTGs are used for powering the onboard systems of spacecrafts.
- 3. RTGs can use Plutonium-238, which is a by-product of weapons development
Which of the statements given above are correct?
Answer b.
Answer (b): statements 2 and 3 are correct. An RTG is not a reactor at all — it has no fission chain reaction, only passive radioactive decay feeding a thermocouple. A radioisotope thermoelectric generator converts the heat of natural radioactive decay — usually of plutonium-238 dioxide — directly into electricity using thermocouples exploiting the Seebeck effect across a hot-to-cold temperature gradient. There is no chain reaction, no criticality, no control rods and no moving parts, so calling it a miniature fission reactor is wrong in principle. Because RTGs run for decades without sunlight, they power deep-space and outer-planet missions — Voyager, Cassini, New Horizons, and the Curiosity and Perseverance rovers. Pu-238 is not found in nature; it is made by irradiating neptunium-237, which is itself recovered from reactor fuel and from the plutonium-production infrastructure built for weapons programmes, which is the sense in which statement 3's 'by-product of weapons development' holds.
Prepared with PrepKar AI and checked; it may contain errors.