N12: Reactor Thermal Hydraulics


Fundamental to the design and safety of a nuclear reactor is the ability to remove energy safely from the core. This module therefore aims to describe the thermal hydraulic processes involved in the transfer of power from the core to the secondary systems of nuclear power plants. The principles of single phase and multiphase fluid dynamics and heat transfer will be studied and applied in the context of a range of different reactor types. The techniques developed will allow you to make assessments of various reactors against thermal limiting criteria.

On completion, students should have obtained:

  • An understanding of the heat transfer mechanisms in reactor systems
  • An understanding of fluid flow mechanisms in reactor systems
  • An appreciation of the limits on safe power removal from reactor cores
  • An appreciation of computer codes used to assess limiting power
  • An understanding of the influence of power conversion methods on reactor design.
  • The ability to perform basic calculations of thermal hydraulic quantities in core channels.


This module is split into two parts and comprises of the following topics:

  • Introduction to Reactor Thermal Hydraulics.
  • Heat transfer in fuel elements.
  • Heat transfer by convection.
  • Boiling heat transfer.
  • Hydraulics of reactor system loops.
  • Hydraulics of heated channels.
  • Thermal hydraulic design.
  • Steam and gas power cycles

For the second part of the module the student will be working on an assignment. This will be to produce the first iteration of a Thermal Hydraulic design for a reactor plant required to supply 1000 MW electrical power, examining aspects such as choice of reactor type, power conversion efficiency, thermal limits on reactor core power, coolant circulation, and heat transfer from the primary circuit.