What is the use of heavy water?

[amp_mcq option1=”It is used in nuclear reactors as a moderator” option2=”It is used in nuclear reactors as fuel” option3=”It is used in radiation therapy for cancer” option4=”It is used in water softening plants” correct=”option1″]

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UPSC Geoscientist – 2023

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Heavy water (D₂O) is deuterium oxide, where hydrogen atoms are replaced by deuterium, an isotope of hydrogen with one proton and one neutron. In nuclear reactors, heavy water is primarily used as a moderator. A moderator slows down the fast neutrons released during nuclear fission to thermal neutron energies, which are required to sustain a nuclear chain reaction, especially in reactors using natural uranium as fuel.

Heavy water acts as a neutron moderator in certain types of nuclear reactors, effectively slowing down neutrons without absorbing them significantly.

Besides being a moderator, heavy water can also serve as a coolant in nuclear reactors. Unlike light water reactors (using H₂O), heavy water reactors can often use unenriched uranium as fuel. While nuclear reactors produce radioisotopes used in cancer therapy, heavy water itself is not used directly in radiation therapy. Water softening typically involves removing hard ions like Ca²⁺ and Mg²⁺, not a function of heavy water.

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