In a nuclear reactor, the moderator is used to
Correct answer: B. slow fast neutrons so that they are more likely to cause further fission
- A. absorb excess neutrons and shut the reactor down
- B. slow fast neutrons so that they are more likely to cause further fission
- C. cool the reactor core
- D. shield the operators from radiation
Explanation
Graphite or heavy water slows the neutrons through repeated collisions, because slow neutrons are far more readily captured by uranium 235 and sustain the chain reaction. Absorbing surplus neutrons to control the rate is the job of the control rods, usually boron or cadmium. Confusing the moderator with the control rods is the standard error here.
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About Composition of Atomic Nuclei
Atomic nuclei contain positively charged protons and electrically neutral neutrons, collectively called nucleons. Questions use atomic number, mass number and nuclear notation to identify isotopes, isobars and isotones, and may connect nuclear composition with nuclear charge, mass defect, binding energy and the stability of the nucleus.
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