UPSC Prelims 2024 · GS Paper I
Question 31: Science and Technology
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 ?
AnswerUPSC’s answer is (b).
A radioisotope thermoelectric generator turns the heat from the natural decay of a radioactive isotope into electricity using thermocouples. It has no chain reaction, so it is not a miniature fission reactor. It powers spacecraft that fly far from the sun, such as Voyager and the Mars rovers Curiosity and Perseverance. Plutonium-238 is a common fuel and is produced as a by-product of the nuclear weapons programme.
- 1. RTGs use heat from radioactive decay; there is no fission chain reaction.
- 2. RTGs power spacecraft instruments and systems far from the sun.
- 3. Plutonium-238, a by-product of the weapons programme, is used as RTG fuel.
How you could have got this
- If you were sure statement 1 is not correct, (a), (c) and (d) go: each of them includes 1.
What you needed to know: RTGs use heat from radioactive decay; there is no fission chain reaction.
Only (b) is left. You didn’t need statements 2 or 3.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) Wrong: statement 1 is false, since RTGs use decay heat, not fission.
- (b) Right: RTGs power spacecraft and can use Plutonium-238.
- (c) Wrong: it accepts the fission claim and drops the spacecraft use.
- (d) Wrong: statement 1 is incorrect.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2024, General Studies Paper I, Series A. The paper on upsc.gov.in.