Introduction

Having described the neutron physics of a fast reactor in Chapter 1 and the behaviour of the fuel elements in Chapter 2, in this chapter we discuss the engineering of the core of a power-producing fast reactor. The three following sections deal with heat transfer, materials and structure.

Heat transfer comes first because the dimensions of the fuel elements and of the core are determined mainly by the demands of heat transfer. The fuel elements have to be of the right dimensions to transfer heat to the coolant at the required rate without overheating. The core has then to be large enough to allow enough coolant to flow through it to take the heat away. This section deals mainly with liquid metal coolants.

Once themain dimensions are fixed the form of the core is determined by the properties of the materials of which it is made, and in particular by the way these properties are affected by neutron irradiation and exposure to the coolant. The structure of the core has then to be designed within these constraints to hold the fuel in place, to allow it to be changed when necessary, to distribute the coolant flow correctly, and to provide for the control rods.