Water plays a pivotal role in energy production, serving as a fundamental resource in various power generation processes. Fossil-fired power plants (FFPP)typically achieve thermal efficiencies of around 50% using supercritical water (SCW), whereas nuclear power plants (NPP) generally achieve efficiencies of about 35%. ECC-SMART aimed to assess the feasibility of a novel source of energy with efficiency above 40 %, combining extensive experience garnered from both FFPP operating under SC conditions and NPP employing water. In addition to larger nuclear units, interest in small modular reactors (SMRs) has resurged, successfully written into the project. Consequently, the European pre-concept of SCW-SMR was designed. While overcoming some preidentified knowledge gaps, the novel SCW-SMR pre-conceptual design arises from the previous EU´s project on supercritical water-cooled reactors. The project provided valuable insights into material behaviour under simulated SCW-SMR conditions, utilising advanced analytical tools to support the safety of future SCW-SMR systems. Improved models and methods for turbulent heat transfer and smooth and rough surfaces at SC conditions were provided and validated. The coupled analyses combining neutronics with thermal-hydraulic calculations were successfully conducted to optimize the core design of EU SCW-SMR. The project consortium has unified the strengths of European, Chinese, Canadian, and Ukrainian initiatives to develop safety criteria for the Small Modular Reactor (SCW-SMR) concept. This work builds on the science-based recommendations from the International Atomic Energy Agency and the Generation IV International Forum for Small Modular Reactors. Project approach includes the principle of defence-in-depth, which employs multiple safety layers, and a focus on physical protection, security, and non-proliferation to ensure responsible development. The guidelines for SCW-SMR safety demonstrations detail essential development stages, safety issues, specific requirements, and necessary experimental support. Additionally, these guidelines address the current legislative status regarding licensing, all of which are comprehensively outlined in the project Deliverables. Collaboration and resource sharing among partners across the world have advanced technology and accelerated project execution. Research under the ECC-SMART project, related to 4th generation reactors, supports the integration of nuclear energy into the energy mix by addressing safety, environmental, and economic factors, and builds on the natural evolution of light water reactors for future energy systems.
