Nuclear Reactors

Some of the key components of a nuclear reactor in terms of chemistry are the fuel, the moderator, the control (or poison), and the coolant.

• The fuel is any fissionable nucleus; for conventional nuclear power this means an isotope of uranium or plutonium.

• The moderator—water, heavy water (D2O), or graphite—is the material within the reactor core that reduces the energy of the bombarding neutrons through elastic and inelastic collisions. A moderator is needed for the suc­cessful operation of thermal reactors, as we will see in the next section.

It should not be a good neutron absorber lest the chain reaction be slowed too much.

• The control is a material that is a good neutron absorber—this material absorbs neutrons as needed to keep the reaction rate under control.

• The coolant is exactly what one would expect: some fluid that can act as a heat sink to carry excess heat away from the reactor core. In conventional nuclear reactors the coolant is water, but for advanced reactors operating at very high temperatures a molten salt or molten metal may be necessary.

Table 9.2 summarizes most of the nuclear reactor designs including those in use and those in the design and development phase (Generation IV). The pressurized light water reactor will be described in some detail as a basis for understanding other types of nuclear reactors.

Updated: September 25, 2015 — 1:44 am