SITEX aims at identifying the efficient means that should be developed through the establisment of a sustainable expertise function network within a European framework with the view to:- allowing mutual understanding between regulatory bodies, TSOs and waste management organisations (WMOs) on (i) the regulatory expectations at decision holdpoints and (ii) how the scientific and technical elements carried out by the WMOs comply with these expectations. In that perspective, the needs in clarification of existing regulatory guidance or in developing new guidance will be addressed. Exchanges with IGD-TP on that issues is favoured. In complement, role of expertise function and the needs for improving it will be discussed;- in coordination with or in complement to WMO's research program, defining TSO's R&D program that would ensure independent capabilities development for reviewing the Safety Case and assessing the scientific arguments provided by WMOs. TSO's R&D program and priorities will be adressed by favouring close interaction with IGD-TP and seeking for joined research activities with the WMOs in order to foster common understanding of technical key points for safety and avoiding undue duplication;- ensuring competence building of experts in charge of technical review and transfer of knowledge on waste safety and radiation protection; the needs in guidance development for harmonising the technical review activity and in dedicated training and tutoring for spreading the expertise culture and practices will be addressed;- sharing, where needed, expertise approach with various stakeholders, in a manner more integrated than when only communication or dissemination are envisaged. Compilation of past actions and learning of ways of implication of stakeholders in the process of technical review will be discussed.