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.

Answer 1

The first statement is correct.

Control rods are lowered into the reactor to slow the chain reaction by absorbing neutrons. (Raising the rods reduces neutron absorption and increases the reaction rate.) Common control rod materials include boron, cadmium and hafnium.