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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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Heat is generated in a nuclear reactor by
Fusion of atoms of uranium
Absorption of neutrons in uranium atoms
Combustion of nuclear fuel
Fission of 235U by neutrons
Fission of 235U by neutrons
Heat generation in a nuclear reactor is primarily a result of controlled nuclear fission of fissile isotopes, most notably 235U. When a thermal neutron is absorbed by a 235U nucleus, it splits into lighter nuclei (fission products), releasing a substantial amount of binding energy in the form of kinetic energy of fragments and heat, along with additional neutrons to sustain the chain reaction.
Heat generation in a nuclear reactor is primarily a result of controlled nuclear fission of fissile isotopes, most notably 235U. When a thermal neutron is absorbed by a 235U nucleus, it splits into lighter nuclei (fission products), releasing a substantial amount of binding energy in the form of kinetic energy of fragments and heat, along with additional neutrons to sustain the chain reaction.
E=Δmc2 — Mass-energy equivalence relation governing the release of energy
Q≈200 MeV — Typical energy released per single fission event of 235U
The process is governed by the mass-energy equivalence principle E=mc2, where the mass defect between the reactant nuclei and product nuclei is converted into energy. In a power reactor, the fuel rods undergo this controlled chain reaction, where the kinetic energy of the resulting fission products is absorbed by the surrounding coolant (water or gas) as thermal energy, which is subsequently converted into steam to drive turbine-generators.
Nuclear fission is an exothermic process involving the splitting of heavy atomic nuclei.
Moderators like graphite or heavy water are used to thermalize fast neutrons to facilitate fission in 235U.
Control rods (e.g., Boron or Cadmium) regulate the reaction rate by absorbing excess neutrons.
The kinetic energy of fission fragments is the primary source of thermal energy in the reactor core.
High energy density compared to fossil fuels.
Low greenhouse gas emissions during operation.
Radioactive waste management concerns.
High capital cost and complex safety requirements.
Base-load electricity generation.
Nuclear-powered marine propulsion (e.g., submarines, icebreakers).
Option A is incorrect because fusion involves combining light nuclei, not uranium.
Option B is incomplete because simple neutron absorption (radiative capture) does not necessarily trigger fission or yield the bulk of the thermal power.
Option C is incorrect as nuclear power relies on nuclear physical reactions, not chemical combustion.
D is correct — Heat in a nuclear reactor is produced by the fission of 235U nuclei initiated by neutron bombardment, which releases binding energy as heat.
Always distinguish between fission (splitting heavy nuclei) and fusion (combining light nuclei); fission is used in all current commercial nuclear power plants.