Introductory Neutronics/Introduction

The subject of nuclear engineering is studied primarily by two groups of professionals:
 * 1) Radiation health physics professionals: those concerned with the medical applications of nuclear physics.
 * 2) Nuclear reactor physics professionals: those concerned with the physics of neutron, fission product, and radiation production and motion within nuclear reactors.

Radiation health physics is the broad term for the medical application of nuclear physics. Radiation health physics is also a science that does the following:
 * analyzes the effects of radiation on biological systems.
 * analyzes the use of radiation for the study of biological systems.
 * recognizes, evaluates, and controls health hazards to permit the safe use and application of ionizing radiation.

Nuclear reactor physics is the branch of science that deals with the study and application of chain reaction to induce a controlled rate of fission within a nuclear reactor for the production of energy. Nuclear reactor physics is usually shortened to reactor physics. Reactor physics covers the following:
 * the interaction of radioactive and non-radioactive inorganic substances.
 * is primarily focused on the inducing and sustaining of nuclear chain reactions.
 * is generally known as neutronics.
 * also covers the transfer of heat and fluid in reactor systems.

The transfer of heat and fluid in reactor systems are critical for maintaining both safety and the physical viability of a nuclear chain reaction. This field of study is generally known as thermo- or fluid-dynamics and is covered by several other texts on wikibooks.

The primary purpose of neutronics is the study and description of the characteristics and distribution of the neutron population within a given volume or system. Because the neutron population is so large, and because calculations and measurements are so crude, this group of particles is generally described in terms of a continuous vector field. This means that calculations in nuclear engineering give values in terms of the average number of neutrons.