[en] In US, and in particular for the DOE Yucca Mountain repository, monitoring is considered to be a significant element in the Performance Confirmation (PC) programme that focuses on the performance and functionality of the disposal system for the purposes of the licensing decision. Other testing and monitoring programmes may deal with other considerations such as increasing confidence or system optimisation aspects. The purpose of the performance confirmation is: - to develop a program of tests, experiments, and analyses to evaluate the adequacy of the information used to demonstrate safety, and - to demonstrate that the system and the sub-system components (i.e. barriers) are operating as anticipated. The performance confirmation activities are classified depending on their purpose e.g. engineering testing and evaluation (to verify the robustness and performance of engineered barriers), science testing and evaluation (to confirm modelling capacity, data etc.). For the license update to allow closure, there is a need to show that safety is still to be expected after closure, and that what has been said has been done. US-DOE has developed a decision analysis approach with aims as followed: - to provide a consistent and sound basis for evaluating and comparing performance confirmation activities; - to use a formal multi-attribute utility analysis in its first phase to develop test and monitoring 'portfolios' and in the second phase for management use. Phase one aims to assess the candidate activities against activity evaluation criteria (defined by the initial workshop participants consisting of technical investigators and performance assessment (PA) analysts and managers). During dedicated workshops, those participants estimate the utility of a specific activity, PA managers providing the necessary management value judgements by reviewing the overall utility. Phase two aims at developing and evaluating alternative portfolios (each candidate activity must demonstrate compliance with basic regulatory requirements and additional requirements such as cost-effectiveness, regulatory robustness and coverage). Phase three consists of selecting portfolios, and phase four consists of updating the program by, for instance, adding one or more activities on the basis of new information (flexibility principle). The performance confirmation activities plan will be regularly reevaluated and updated. Actually, from twenty activities, eleven were begun during the site characterisation (e.g. unsaturated zone testing) two of them will be carried out during the construction phase (e.g. seal testing) and seven activities will begin during operations (e.g. corrosion testing, drift inspection). The path forward for the Yucca-Mountain-DOE performance confirmation is mainly to define activities (what, when, where and how), to establish the expected baseline for performance confirmation activities (required by regulator), to identify and develop test plans and procedures, to develop an integration group to asses data as a whole, and to define process for defining, detecting and reporting variances and for deciding on the appropriate action