PHYSICS · Single correct · A Level · Physics · Nuclear physics · Nuclear physics
Problem
In a pressurised-water nuclear reactor, inserting control rods between fuel assemblies rapidly reduces the reactor’s power output. Which of the following statements most directly accounts for this effect?
(a) The control rods absorb γ radiation produced in fission, thereby removing energy that would have maintained the chain reaction.
(b) The control rods slow down fast neutrons so much that the neutrons no longer have enough energy to induce fission.
(c) The control rods absorb free neutrons, lowering the probability that subsequent nuclei will undergo fission.
(d) The control rods reflect neutrons out of the core, so fewer neutrons strike other fuel nuclei and the chain reaction subsides.