An attempt has been made to study bond strength history in Prestressed Concrete Reactor Vessels (PCRV) which house the Advanced Gas-cooled Reactors. Three-dimensional non-linear analytical model has been developed in which the effect of bond is included. A finite element computer program is written in which solid, membrane, line and bond-linkage elements have been used to represent vessel concrete, steel liner, pre-stressing tendons and bond (between steel and concrete) respectively. Concrete is assumed to be non-linear material in compression and linear brittle (tension cut-off) material in tension, and the steel as elasto-plastic material with strain hardening. Provision is also made for concrete cracking, crushing and visco-elastic creep. Two experiments have been carried out during this research. The purpose of the first experiment was to determine bond coefficients required for the analysis. This was achieved by pull-out tests on prestressing specimens using 5 mm and 7 mm diameter prestressing wires. The second experiment was performed on an octagonal prestressed concrete slab representing a top cap of a reactor vessel. The experimental results obtained from this slab are corroborated with the analytical results. A typical Prestressed Concrete Reactor Vessel with boilers and circulators housed within the vessel wall thickness has been analysed for bond strength under increasing gas pressure at suitable intervals of its 30 year life. A comparison is made between the unbonded and bonded vessels. All analytical results compare well with those obtained from the experiments and available published data.