This publication presents the outcome of an IAEA coordinated research project (CRP) on methodologies for assessing pipe failure rates in advanced water cooled reactors. The goal of the CRP was to provide Member States with a strong technical basis for establishing nuclear power plant piping reliability parameters. To meet this goal two parallel and interrelated activities were carried out. In a first CRP activity, the participating institutions performed a series of benchmark studies. These studies, as described in this publication, were formulated for the purpose of evaluating different methodologies when applied to a common problem. The results were compared, and the reasons for differences were identified. This publication provides a description of the benchmark studies, the participants' individual methodologies applied, and simulations and analyses carried out, an independent synthesis of the results, and the main insights and conclusions from the exercise.