PEBBLE BED REACTORS
Pebble
Those reactors are fuelled and moderated by graphite fuel spheres each containing TRISO coated low enriched Uranium or Thorium oxide fuel particles. There are 15000 fuel particles per fuel sphere the size of a billiard ball. Each fuel pebble contains 9 g of fissile material.
Those reactors are fuelled and moderated by graphite fuel spheres each containing TRISO coated low enriched Uranium or Thorium oxide fuel particles. There are 15000 fuel particles per fuel sphere the size of a billiard ball. Each fuel pebble contains 9 g of fissile material.
Reactor
design
The concept of PBR has been developped in Germany (AVR reactor and
THTR). It
uses a Brayton closed-cycle gas turbine. The core design is
annular
with a centre column as a neutron reflector. In this reactor,
pyrolytic graphite is used to moderate the chain
reaction instead of water. The heat exchange fluid is an inert gas
like Helium, Nitrogen or Ccarbon dioxide which leaves the kernel at a
very high temperature and feeds the turbine..