Advanced Gas Cooled Reactors

Fuel – Uranium Dioxide with 3% 235U enrichment
Cladding – stainless steel
Moderator – graphite
Coolant – CO2 gas
Control – boron steel rods
Shield – reinforced concrete

The AGR's higher thermal efficiency compared to Magnox reactors required higher temperatures which required stainless steel cladding which has a higher neutron capture cross section leading to enriched fuel. 

UK AGR Reactors

Dungeness B in Kent, 2 units Connected in 1983 and 1985
Total 1110 Mwe

Hartlepool in Durham, 2 units connected in 1983 and 1984
Total 1210 MWe

Heysham 1 and 2 in Lancashire, 4 units connected in 1983, 1984 and 1988
Total 1150 and 1250 Mwe

Hinkley Point B in Somerset, 2 units connected in 1976
Total 1220 MWe

Hunterston B in Ayrshire, 2 units connected in 1976 and 1977
Total 1190 MWe

Torness in East Lothian, 2 units connected in 1988 and 1989
Total 1250 MWe