UPSC Prelims 2011·GS1·science-and-technology·nuclear technology

The function of heavy water in a nuclear reactor is to

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Last updated 23 May 2026, 3:31 pm IST
  1. ASlow down the speed of neutronsCorrect
  2. BIncrease the speed of neutrons
  3. CCool down the reactor
  4. DStop the nuclear reaction

Explanation

The correct answer is A because heavy water acts as a moderator in a nuclear reactor. In the process of nuclear fission, neutrons are released at very high speeds. For a sustained chain reaction to occur, these fast moving neutrons must be slowed down to become thermal neutrons, which are more likely to be captured by the fuel nuclei like Uranium 235. Heavy water effectively reduces the kinetic energy of these neutrons through collisions without absorbing them significantly, thereby facilitating the fission process. While water can also act as a coolant, its primary specialized function in this context is moderation.
science-and-technology: The function of heavy water in a nuclear reactor is to
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