NDA (I) 2024 General Ability Test · Question 125 of 146

Correct — C, a mechanism to reduce CO2 emission. A nuclear reactor makes power by nuclear fission, which splits heavy nuclei and releases heat without burning any fuel — so it produces no carbon dioxide at the point of generation and needs no device to cut CO2. The other three are genuine parts of a nuclear power station: the reaction chamber (the core or reactor vessel) is where fission occurs, a heat exchanger transfers that heat to water to raise steam, and the steam spins a turbine that drives the generator. The odd one out is therefore option (c).

• (a)A turbine — The heat from fission boils water into high-pressure steam, which drives a turbine coupled to a generator to make electricity — a turbine is a core part of the plant.
• (b)A heat exchanger — In most reactors a heat exchanger (the steam generator) passes heat from the reactor coolant to a separate water loop to produce steam; it is a standard component.
• (d)A reaction chamber — The reactor core or vessel is exactly where the controlled fission chain reaction takes place, so it is central to any reactor.

A nuclear power plant turns the heat of nuclear fission into electricity. The reactor core (reaction chamber) heats a coolant; a heat exchanger transfers that heat to make steam; the steam spins a turbine linked to a generator. Because fission does not burn carbon, the process releases no carbon dioxide at the point of generation.

The trap is that CO2-reduction sounds environmentally relevant and so seems to 'belong'. But CO2 capture is a feature of fossil-fuel plants that burn coal, oil or gas. A reactor emits no CO2 while running, so it has nothing to reduce — which is what makes option (c) the misfit.

• Nuclear reactors generate heat by fission of nuclei such as uranium-235, releasing no carbon dioxide at the point of generation.
• The reactor core (reaction chamber) houses the fuel rods and the controlled chain reaction.
• A heat exchanger, also called the steam generator, transfers heat from the coolant to produce steam.
• The steam drives a turbine connected to a generator, the same electricity-producing stage as in a thermal power plant.

• Assuming every power plant needs CO2 controls — only fossil-fuel plants emit CO2 while running.
• Confusing the heat exchanger (which raises steam) with the turbine (which spins to generate power).
• Thinking the reactor makes electricity directly, rather than first producing heat that raises steam.

An odd-one-out on reactor parts — recall the core to heat-exchanger to turbine chain and that fission emits no CO2.

• practice — not a real PYQ

  In a nuclear power plant, the device that converts the energy of steam into mechanical rotation to run the generator is the:

  • (a)Reactor core
  • (b)Turbine
  • (c)Control rod
  • (d)Moderator

  Answer(b) Turbine — high-pressure steam spins the turbine, which is coupled to the generator.

• practice — not a real PYQ

  Compared with a coal-fired plant, electricity generation in a nuclear reactor:

  • (a)burns fuel and releases CO2
  • (b)releases no CO2 at the point of generation
  • (c)needs no turbine
  • (d)produces electricity without any heat

  Answer(b) releases no CO2 at the point of generation — fission produces heat without burning carbon.