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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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Deuterium oxide is used in nuclear reactors as
Fuel
Moderator
Shield
Regulator
Moderator
Deuterium oxide (D2O), commonly known as heavy water, is used as a moderator in nuclear reactors to slow down high-energy fast neutrons to thermal energies. This process increases the probability of these neutrons inducing fission in fissile isotopes like 235U.
Deuterium oxide (D2O), commonly known as heavy water, is used as a moderator in nuclear reactors to slow down high-energy fast neutrons to thermal energies. This process increases the probability of these neutrons inducing fission in fissile isotopes like 235U.
Ek=21mv2 — kinetic energy of a neutron
σs — scattering cross-section (which is high for D2O)
In a fission reaction, neutrons are released at high velocities. A moderator consists of nuclei with low mass numbers that absorb kinetic energy from neutrons through elastic collisions. Since the mass of the deuterium nucleus is close to that of a neutron, D2O is highly effective at moderating neutrons while having a very low neutron capture cross-section.
Heavy water (D2O) has an extremely low absorption cross-section for thermal neutrons.
It allows the use of natural uranium as fuel because of its efficiency as a moderator.
Used extensively in CANDU (Canada Deuterium Uranium) reactors.
Allows usage of natural uranium (non-enriched fuel).
High moderating ratio.
Excellent thermal properties for heat transfer.
High production cost of heavy water.
Requires high isotopic purity.
Research reactors.
Power production in CANDU-type nuclear plants.
Heavy water is chemically similar to ordinary water (H2O) but contains the isotope deuterium (2H).
Option A (Fuel) is incorrect; fuels are typically U235, Pu239, etc.
Option C (Shield) usually refers to concrete or lead structures used for biological protection against radiation.
Option D (Regulator) is a generic term not specifically used to describe a moderator's function.
B is correct — Deuterium oxide serves as an efficient moderator by thermalizing fast neutrons through elastic scattering collisions.
Remember that a good moderator must have a low atomic mass to effectively transfer energy and a low probability of neutron capture to ensure chain reaction sustainability.