Question

Which statement describes the use of control rods?
Control rods are lowered into the reactor to slow down the reaction by absorbing neutrons.
Control rods are lowered into the reactor to speed up the reaction by releasing neutrons.
Control rods are raised out of the reactor to slow down the reaction by absorbing neutrons.
Control rods are raised out of the reactor to speed up the reaction by releasing neutrons.

Answer 1

Control rods are lowered into the reactor to slow down the reaction by absorbing neutrons.

Explanation: inserting (lowering) control rods increases neutron absorption, reducing the neutron population and slowing the fission chain reaction; withdrawing (raising) them decreases absorption and allows the reaction to speed up.