Nuclear fission is a process in which an atom splits and releases energy, fission products, and neutrons. The neutrons released by fission can, in turn, cause the fission of other atoms.

EO 4.1EXPLAIN the fission process using the liquid drop model of a nucleus.

EO 4.2DEFINE the following terms:

a. Excitation energy

b. Critical energy

EO 4.3DEFINE the following terms:

a. Fissile material

b. Fissionable material

c. Fertile material

EO 4.4DESCRIBE the processes of transmutation, conversion, and breeding.

EO 4.5DESCRIBE the curve of Binding Energy per Nucleon versus mass number and give a qualitative description of the reasons for its shape.

EO 4.6EXPLAIN why only the heaviest nuclei are easily fissioned.

EO 4.7EXPLAIN why uranium-235 fissions with thermal neutrons and uranium-238 fissions only with fast neutrons.

Fission

In the fission reaction the incident neutron enters the heavy target nucleus, forming a compound nucleus that is excited to such a high energy level ( > )that the nucleus "splits" (fissions) into two large fragments plus some neutrons. An example of a typical fission reaction is shown below.

A large amount of energy is released in the form of radiation and fragment kinetic energy.