FUEL ELEMENTS: BASIC TYPES

Since the very beginning, different types of fuel elements have been developed. Over the years, for each reactor type a particular fuel design evolved which can be considered today as a standard fuel element.

The fuel elements of Pressurized Water Reactors PWR and Boiling Water Reactors BWR are heavy metallic constructions. The fuel is enclosed in thin-walled zirconium alloy tubes of about 4 m length and of 10 mm diameter, the so-called fuel rods.

The fuel elements of the heavy water reactor CANDU or the gas-cooled reactor AGR have a similar, but much shorter design.

In High Temperature Reactors HTR pebbles or cylindrical compacts are applied where the fuel is encapsulated in a graphite shell.

Even for complex constructions, the shape of the fuel containing components can be reduced to a few simple basic geometries

  • cylinders
  • spheres.

It is our objective to use the same simple geometries for complex fuel elements with ceramic cladding:

  • cylindrical compacts and small cylindrical capsules
  • pebbles.