ABSTRACT
A reactor can be thought of as a nuclear furnace that transfers the heat it produces to the coolant that flows through the core. The flow of fluid within the core, within the pressure vessel, and within the plant as a whole is completely bounded by solid surfaces on all sides. The fluid particles move past each other in orderly layers that resemble the laminates used to cover some types of woods, metals, and plastics. When the velocity of a fluid becomes high enough, the motion of the fluid begins to become disordered, and the flow field that was initially laminar begins to develop small eddies and vortices in it. The flow of fluid through a reactor core can be either forced or unforced depending upon the circumstances that cause the fluid to flow. The fluid field must also be coupled to the heat transfer field, and both of these fields may change as a function of time.
