Question 93 from UPSC CSE 2024 - Current Affairs (S&T)

Question

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?

IASCODEX · Accepted Answer

Correct Option: B. 2 and 3 only

Strategy: -   Reject statement 1: RTGs use radioisotope decay, not nuclear fission.
-   Confirm statement 2: RTGs are standard power sources for spacecraft, based on past space missions.
-   Validate statement 3: Plutonium-238 is the common RTG isotope and is produced as a by-product of specific nuclear processes.

Key Info: ## Radioisotope Thermoelectric Generators (RTGs)

RTGs are power sources that convert heat released by the radioactive decay of isotopes directly into electricity using thermoelectric materials.

### Key Characteristics:

*   **Mechanism:** RTGs rely on the steady decay of radioisotopes, primarily Plutonium-238 (Pu-238), rather than nuclear fission or chain reactions, which distinguish them from nuclear reactors.
*   **Primary Isotope:** Pu-238 is favored for its high power density, predictable heat output, and relatively low gamma radiation.
*   **Pu-238 Production:** It is produced as a by-product in nuclear reactors from Neptunium-237, often associated with processes linked to military plutonium production.

### Applications & Advantages:

*   **Deep-Space Missions:** RTGs have been crucial power sources for deep-space missions like Voyager, Cassini, New Horizons, Curiosity, and Perseverance rovers, especially where solar power is impractical.
*   **Reliability:** NASA and other space agencies prefer RTGs for their long operational lifespans, reliability in harsh environments, and lack of moving parts.
*   **Other Uses:** They are also pivotal in remote applications such as Arctic/Antarctic stations and some lighthouses.

**Note:** Miniature fission reactors, such as Kilopower, operate fundamentally differently by sustaining controlled fission chain reactions.

IASCODEX · Answer

Option A: 1 and 2 only

IASCODEX · Answer

Option C: 1 and 3 only

IASCODEX · Answer

Option D: 1, 2, and 3