Recently, a number of creep cracks have been found in complex pipe to pipe intersections, referred to as bifurcations in the boilers of the UK¿s Advanced Gas Cooled Reactors (AGRs). The purpose of the present experiment is to quantify the distribution and magnitude of residual stresses present in mock-up bifurcation components in order to predict the remaining life of other bifurcations and to underwrite future safe operation of the plant at reduced load. The measurements will be used to validate predicted stresses from a state of the art finite element (FE) model being used to simulate the complete fabrication process and cyclic service load-history. Measurements of axial, radial and hoop stresses will be made using 1mm and 3mm, collimators at locations indicated by the FE results as being of primary interest.