The buffer store accepts freshly discharged fuel as­semblies whilst their fission product heat generation decays to a rate compatible with the cooling arrange­ments at the irradiated fuel disposal facility (IFDF). It consists of a number of water-cooled pressure tubes, known as buffer tubes, within which the fuel assemblies are placed and cooled by the natural con­vection of heat to the pressure tube walls by pres­surised carbon dioxide.

Only eight buffer tubes were provided initially at Hinkley Point В but a further 14 were subsequently added. The decision to extend the facility resulted from operational experience of part load batch refuel­ling which had not been originally envisaged as a normal operational route. At Heysham 2, the fuel route was designed from the outset to permit a 28 day cooling period for all fuel assemblies prior to transfer to the irradiated fuel disposal facility, as a means of easing the duty on the cooling system for that cell. In consequence, the buffer store at Heysham 2 contains 32 buffer tubes.