Nuclear Engineering Principles 7

Water moderator and coolant

Graphite moderator, water coolant

Graphite moderator, CO2 coolant

Heavy water moderator and coolant

No moderator, liquid metal coolant

Enriched UO2 (4-5%)

Low enriched UO2 (2-3%)

Pu or mixed fuels

Enriched U-235 to <20%

Natural unenriched U

To slow down fast neutrons

To speed up thermal neutrons

To act as a safety mechanism

To absorb neutrons

To prevent radioactivity release in an accident

To protect the reactor from terrorist attacks

To protect the reactor from natural disasters

To provide shielding to site workers

Boron

Cadmium

Hafnium

Steel

1

2

3

4

They have enhanced safety features

They are more expensive to build

They can be decommissioned in situ

They will use HALEU fuel

FNRs

PWRs

AGRs

HTRs

I

II

III

IV

They cannot be restarted when shut down if using liquid metal coolants

They can use molten salts as coolants

They are expensive to build

They can use a range of fuels