Integrated performance assessments (IPAs) of radioactive waste repositories deep underground are made at different stages of repository development in order, for example, to allow full-scale development, to provide feedback to R&D, and to test and develop review capability. IPA studies must be acceptable to a wide range of stakeholders and are one of the bases for dialogue amongst regulators and implementers of disposal facilities.

The goal of the IPAG-2 study was to examine the experience of regulatory reviews of IPAs, from both the implementer and regulator points of view. Ten implementer and seven regulatory organisations participated. This report presents the lessons learnt from their review experiences, and provides recommendations to aid future regulatory decision making.