Accurate assessment of neutron fluence at reactor pressure vessels and other internal components such as core shrouds is a crucial component of radiation damage studies, which are of fundamental importance in determining plant life. In recent years the Monte Carlo calculation method has become recognized as an accurate tool for such assessments. AEA Technology, through its development of the MCBEND Monte Carlo code in collaboration with BNFL, has been a key innovator in the development of the Monte Carlo method and in making these developments easily accessible to the user. Recent developments aimed at fluence modeling include a source processor, a point energy adjoint capability and geometric sensitivities. The code has been applied to fluence modeling in Magnox gas cooled reactors and PWRs for a number of years : with the work described in this paper it has now also been successfully applied to BWR fluence analysis.