Assessment of ASTEC Thermal-Hydraulics against Plate Compact Steam Generator Experiments

Resumen

Small Modular Reactors (SMRs) are receiving important attention due to the increasing demand for clean, reliable and cost-effective energy solutions. SMR designs incorporate compact features, inherent safety through passive cooling systems and lower core inventories compared to conventional power plants. Among the different components of SMRs compact steam generators play a key role since they are devoted to the heat transfer from the primary to the secondary circuit. The use of a plate-type steam generator in an integral SMR offers the potential advantage for high-power transfer in an extremely compact configuration. While the technology of plate heat exchanger is not new, its integration within SMRs, including its coupling with a passive secondary loop and condenser to ensure reliable cooling in accidental conditions, is innovative. Therefore, careful studies and tests are necessary to meet the nuclear safety standards. Considering this, the EU-funded ELSMOR (towards European Licensing of Small Modular Reactors) project (2019-2023) aimed to improve the European capacity in evaluating and developing novel SMRs. As part of ELSMOR, an extensive experimental campaign was performed at a facility operated by SIET (Società Informazioni Esperienze Termoidrauliche, Italy) to assess the Emergency Heat Removal System of an experimental SMR. The facility consisted of a natural circulation loop connected to a primary side by a plate-type Safety-Compact Steam Generator (S-CSG), transferring heat to a water pool using a vertical tube heat exchanger. To evaluate the validity and performance of the European reference severe accident code ASTEC (Accident Source Term Evaluation Code), developed by IRSN (France), for SMRs, an ASTEC representation of the natural circulation loop and the S-CGS of the SIET facility has been developed and assessed in the framework of a KIT, IRSN, and JRC collaboration. The results of the verification phase against key and representative experiments are presented and discussed. ASTEC v3.1 results show a satisfactory agreement against the experimental data.