6 Transmission System Operators (Belgium, France, Greece, Norway, Portugal and United Kingdom) and CORESO, a TSO coordination centre, together with 13 RTD performers propose a 4 year R&D project to develop and to validate an open interoperable toolbox which will bring support, by 2015, to future operations of the pan-European electricity transmission network, thus favouring increased coordination/harmonisation of operating procedures among network operators. Under the coordination of RTE, new concepts, methods and tools are developed to define security limits of the pan European system and to quantify the distance between an operating point and its nearest security boundary: this requires building its most likely description and developing a risk based security assessment accounting for its dynamic behaviour. The chain of resulting tools meets 3 overarching functional goals: i) to provide a risk based security assessment accounting for uncertainties around the most likely state, for probabilities of contingencies and for corresponding preventive and corrective actions. ii) to construct more realistic states of any system (taking into account its dynamics) over different time frames (real-time, intraday, day ahead, etc.). iii) to assess system security using time domain simulations (with less approximation than when implementing current standard methods/tools). The prototype tool box is validated according to use cases of increasing complexity: static risk-based security approach at control zone level, dynamic security margins accounting for new power technologies (HVDC, PST, FACTS), use of data coming from off-line security screening rules into on-line security assessment, and finally security maps at pan European level. Dissemination is based on periodic workshops for a permanent user group of network operators invited to use modules to meet their own control zone needs and the ones of present or future coordination centres.