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?

Radioisotope Thermoelectric Generators (RTGs) are lightweight and compact power systems used in spacecrafts, known for their reliability.

RTGs generate electricity from the heat produced by the natural radioactive decay of plutonium-238 (in the form of plutonium oxide). The temperature difference between the hot fuel and the cold space environment is used to generate an electrical current via thermocouples.

Statement 1 is incorrect. RTGs are not fission reactors. They rely on radioactive decay, not nuclear fission.

Statement 2 is correct. RTGs are indeed used to power onboard systems of spacecraft. NASA has been using this technology since the 1960s.

Statement 3 is correct. Plutonium-238 (Pu-238) can be used in RTGs due to its relatively low half-life. It is a by-product of nuclear activities and although it can be related to weapons development, its use in RTGs is distinct.

Hence, statements 2 and 3 are correct.

Sources:

• NASA - Radioisotope Power Systems
• World Nuclear Association - Radioisotope Thermoelectric Generators (RTGs)