Concept:Control rods absorb excess neutrons to regulate the fission chain reaction, but they cannot change the natural speed of neutrons produced by fission.
Explanation:In a controlled thermal fission reactor, control rods are made of neutron-absorbing materials.
By absorbing neutrons, they reduce the rate of neutron production and slow down the chain reaction.
This directly affects the rate of energy generated and the amount of radiation produced in the reactor.
However, the speed of the neutrons released during the fission process depends on the fission event itself, not on the control rods.
Therefore, control rods do
not affect the speed of the neutrons released on fission.
Answer:C. speed of the neutrons released on fission.