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| Hauptseite > Publikationsdatenbank > Analysis of postulated severe accidents in generic integral PWR small modular reactors in the frame of the Horizon EURATOM SASPAM-SA project |
| Hauptseite > Publikationsdatenbank > Analysis of postulated severe accidents in generic integral PWR small modular reactors in the frame of the Horizon EURATOM SASPAM-SA project |
| Abstract | FZJ-2025-01683 |
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2024
Abstract: Currently, there is a growing interest in Europe in the deployment of Small Modular Reactors (SMRs). One family of SMR,the Integral Pressurised Water Reactor (iPWR), is ready to be licensed as a new build. Despite the reinforcement of the firstthree levels of the Defence-in-Depth (DiD), a sound demonstration of iPWR ability to address Severe Accidents (SA) andhandle offsite protecting countermeasures in case of radiological releases should be carried out (DiD Levels 4 and 5). In thiscontext, the HORIZON-EUROPE project ‘Safety Analysis of SMR with PAssive Mitigation strategies - Severe Accidents’(SASPAM-SA), coordinated by ENEA and launched in 2022, aims at at investigating the applicability and transfer of thecurrent reactor safety knowledge and know-how for large Light Water Reactors (LWR) to iPWRs, in the view of theEuropean licencing needs related to SA and Emergency Planning Zone (EPZ) analyses.Elements not addressed in other on-going iPWR initiatives are the pillars of the project: a) identification and analysis ofpostulated SA scenarios; b) identifying the RPV and containment conditions characterizing iPWR SA scenarios that mightdiffer from large-LWRs; c) investigating existing experimental database for iPWRs and additional needs; c) capability ofEuropean and non-European (but widely used in Europe) codes for SA and radiological impact on-/off- site analyses iniPWRs.For maximizing knowledge transferability and project impact, two generic iPWR concepts are considered: ‘Design-1’ (60MWe) with a submerged containment; ‘Design-2’ (300 MWe) employing several passive systems and a dry containment.These two iPWR designs incorporate the main design features of the most promising designs ready for deployment in theEuropean market.This paper focuses on the activities of the ‘Input deck development and hypothetical SA scenarios assessment’ WorkingPackage (WP) 2, coordinated by KIT. It aims at assessing generic, but representative, SA and CFD codes’ input decks,analyzing the iPWRs’ behaviour in hypothetical SA conditions, and investigating the codes’ capability to simulate the dominantphenomena driving the scenarios. A set of Design Basis Accident (DBA) and SA scenarios are postulated and analysed. Itshould be noted that since no Probability Safety Assessment (PS) considerations are done in the project (generic designs areconsidered), the SA scenarios are analysed in terms of severity and not of probability to occur. Major outcomes will be theboundary conditions influencing accident management strategies, like In-Vessel Melt Retention and Filtered ContainmentVenting, and quantitative bases to estimate EPZs.In the paper, the results of the analyses of postulated DBA and SA scenarios in both iPWR designs performed by means of SA(AC2, ASTEC, MELCOR, MAAP, EDF-MAAP) and CFD (containmentFOAM, Ansys CFX) codes are discussed. Thepreliminary results have shown that SA codes (AC2, ASTEC, MELCOR, MAAP) can reproduce the main thermal-hydraulicsand in-vessel degradation phenomena during the scenarios, showing consistent values and trends in the primary variables ofthe sequences analysed, i.e. main events timing, hydrogen mass production, and corium mass.
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