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The PASTELS project will demonstrate how innovative passive safety systems can support modernisation and optimisation of the European nuclear industry

The overall objective of PASTELS is to improve the ability of European nuclear actors to design and deliver innovative passive safety systems – which are particularly promising as they do not rely on power supply or human intervention – and simulate their behaviour to support the safety demonstration.


PASTELS will make significant progress in the study of two specific passive systems, the Containment Wall Condenser (CWC) and the Safety Condenser (SACO) by: • Building on and leveraging existing available computational codes to simulate the relevant thermal-hydraulic phenomena, • Developing a robust, validated, multi-scale simulation methodology of passive systems, • Performing new experimental studies to obtain the relevant validation data. The project will deliver extensive methodology guidelines as well as a roadmap to achieving the licensing and implementation of these innovative passive system technologies in future European Nuclear Power Plants (NPPs). The PASTELS project has obtained the NUGENIA label on 23/09/2019 (Certificate number: 2019NUG0076). Project context Safety issues are at the forefront in the design of nuclear power plants. The Fukushima Daiichi nuclear accident in 2011 showed the vulnerability of NPPs to the loss of electrical power and the heat sink events that ensued. During the accident, the insufficient performance of the heat removal system resulted in a core meltdown and the spreading of radioactive material into the surroundings with several hundred billion dollars’ worth of damages being caused according to the Japanese government. Prevention and mitigation strategies for these events were analysed and have led to the need for safer and more reliable residual heat removal solutions. Among the possible solutions, innovative passive systems have the intrinsic advantage of not being dependent on energy supply and being able to operate autonomously for a long time without any intervention of a human operator to fulfil their function. Passive systems are an additional option given to nuclear power plant designers independently of the generation of the reactor. They form the basis of many Small Modular Reactors (SMR) and are considered as one of the “most promising emerging technologies in nuclear power” according to the Atomic Energy Agency (IAEA). At an international level, outside the European Union, innovative passive systems have been chosen as parts of several nuclear power plants and in many recent designs of GEN III reactors. However, European manufacturers have little first-hand experience of thermal-hydraulic behaviour of these systems, while the implementation of efficient passive systems is considered as an important option for the improvement of the safety. In-depth analyses and studies are still needed to properly evaluate the benefit of such systems and identify, if any, the drawbacks when used in European nuclear power plants. Partnership PASTELS brings together eleven European organisations with complementary skills and expertise which, by combining altogether, will make significant progress in the study of passive systems: • Electricité de France (France) • Agenzia nazionale per le nuove technologie, l’energia et lo sviluppo economico sostenibile (Italy) • Commissariat à l’énergie atomique et aux énergies alternatives (France) • Framatome GmbH (Germany) • Gesellschaft fur anlagen und reaktorsicherheir GmbH (Germany) • Universität Stuttgart (Germany) • Institut de radioprotection et de sûreté nucléaire (France) • Lappeenrannan-Lhaden teknillinen yliopisto LUT (Finland) • Paul Scherrer Institut (Switzerland) • ÚJV Řež (Czech Republic) • ARTTIC (France) The PASTELS consortium is supported by an Advisory Board composed of experts who will provide regular feedback and advice to the project on compliance to regulations as well as scientific excellence. Project website :


energy, nuclear energy, nuclear industry, safety