control rod
noun
a neutron-absorbing material, as boron or cadmium, in the shape of a rod or other configuration, that can be moved into or out of the core of a nuclear reactor to regulate the rate of fission.
Origin of control rod
First recorded in 1940–45
Words nearby control rod
British Dictionary definitions for control rod
control rod
noun
one of a number of rods or tubes containing a neutron absorber, such as boron, that can be inserted into or retracted from the core of a nuclear reactor in order to control its rate of reaction