Delphine Meyer

Fulvio Mascari

Luis E. Herranz

Olivia Coindreau

Sandro Paci

Sara Beck

Stephan Brum

Victor H. Sánchez

English

Victor H. Sánchez

Archivio della Ricerca - Università di Pisa

10/11/2021MUSA has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 847441.The MUSA Project: Halfway to the EndLuis E. Herranz (CIEMAT), Delphine Meyer (LGI), Sara Beck (GRS), Victor H. Sánchez (KIT), Fulvio Máscari (ENEA), Stephan Brum (JRC), Olivia Coindreau (IRSN), Sandro Paci (UNIPI)12Objectives and ScopeTo establish a harmonised approach for the analysis ofuncertainties and sensitivities associated with severeaccident (SA) analysis among EU and non-EU entities.To assess the capability of SA codes when modelling accidents• Identification and characterization of input & models uncertainties.• Adaptation of available UASA methodologies.• Application to postulated NPP scenarios.• Building recommendations on how to bring BEPU to SA analysis.Gen II, Gen III & Gen III+ // Reactor & SFP // Source Term Focused/ SAMs1210/11/20213Major Impactso A systematic assessment of the uncertainty band affecting ST in risk dominantsequences.o Guidelines to systematic conduct BEPU analysis in the SA domain.o A database with the characterization (U&LBs and pdf) of uncertainties in inputdeck parameters.o Insights into key elements affecting SAM implementation (i.e., timing).o Additional means/actions that might optimize the accident management, bothin reactors and SFPs.o Hands-on training & identification of major challenges of bringing BEPU into SAanalyses.4MUSA Structure & Governance3410/11/20215MUSA Internal Networking6MUSA Gantt Chart5610/11/2021MUSA and COVID-197Early monitoring of the effects on MUSA (CIEMAT and LGI) (mid 03/20)o MUSA partners surveyed: operational status and specific impact on MUSA?o Close follow-up by the ExB. Impacts translated in terms of:o Direct delays in ongoing, starting or under preparation activities.o Partners networking in face-to-face meetings.o “Remote” running of SA codes is far from being onsite running. EC PO officer informed, as of 09/20.Effective & sizeable impact on MUSA progress (weakening networking).8WPs Current Statuso WP1 - Fully implemented and operational.o WP2 - ST FOMs (+ add. Variables) determined.Directory being built with relevant phenomena for ST and characterizationof key input uncertainty parameters (LB;UB; PDFs). Critical review needed!Feedback from WP4, WP5 & WP6 just started.o WP3 - UQ tools reviewed provide the basic necessary capabilities.Being tested in WP4; getting ready for further use in WP5 and WP6.Recommendations.Issues: range of input uncertainty parameters, appropriate PDFs, Wilksapplicability in case of multiple FOMs, etc.7810/11/20219WPs Current StatusoWP4 - Application of the UQ methodologies and first report of UASA challenges.oWP5 - Four groups (BWR, VVER, PWR GEN II, PWR GEN III).Reference plant models developed.UQ just started (mostly training with the scenarios).High computing cost; solutions under discussion.o WP6 - FOMs adapted to the SFP scenarios.Transient scope limited to a moderate damage of spent fuel rods. Development of the reference case done (UQ under preparation).AM actions have been reviewed. o WP7 - Struggling with the current pandemic conditions. Moderate progress in D&C: a lecture; a fundamental journal article; several papers in intl. and natl. conferences.Production should rocket the coming year.10WP4 Bases: Documentation2nd General MUSA Project Meeting, 4. November 2021Specifications to apply UQ Methods against PHEBUS-FPT1 Data needed to develop an input deck and apply UQ.First two experimental phases (degradation and the aerosol phases )o Computational domain (temporal and spatial domains)o Geometry and material properties (material data, instrumentation)o Initial and boundary conditions• Nuclear power history• Power distribution (axial, radial)• Inlet steam flow history and pressure• Fission product inventory• Thermal boundary conditions• Initial composition of the atmosphere in the containment91010/11/202111WP4 Bases: FOMs• Release of iodine from top of the bundle [% of i.i.]• Release of cesium from top of the bundle [% of i.i.]• Cesium retention in the circuit [% of Cs released from the core]• Aerosol amount in the containment atmosphere [g] • Total gaseous iodine amount in the containment atmosphere [g] • Total iodine aerosols amount in the containment atmosphere [g]• Total deposited/adsorbed iodine amount in the containment [g]12WP4 Bases: Structure of UASA111210/11/202113WP4 Bases: Major Challenges• SA code and UT coupling (e.g., scripts);• Managing of failed calculations and debugging;• Post processing;• Implementation of the SA code and UT in computing clusters .14WP4 Challenges: Post-processing0.5 1 1.5 2 2.5 3Time (s) 104-0.8-0.6-0.4-0.200.20.40.6CHIGAMMAFSLIPSTICKTURBDSTKGOPFTHERMDELDIF131410/11/202115WP5: Grouping2nd General MUSA Project Meeting, 4. November 2021PWR Gen IIICNPRI5 partnersPWR Gen IIKIT10 partnersVVER/CANDUINRNE6 partnersBWRJRC5 partners16Best estimate base case calculations: 23/25 Code coupling and “proof of concept “: 15/25Scripting recommended (free statistics and post- processing). Some testing of methods undergoing: large number of uncertain parameters (u.p); correlation of u.p.; application to ex-V phase, …Current status - Description2nd General MUSA Project Meeting, 4. November 2021151610/11/202117Current status – iIlustration of results3/5ENEA: PWR 900 - MELCOR+DAKOTA - SBO2nd General MUSA Project Meeting, 4. November 2021Pearson’s coefficient. left f(t); right: at t | FOM(t) = max Pearson Correlation Coefficient SNERDI: CAP1400 - MAAP4+DAKOTA - SGTR Jacobs: ABWR - MELCOR+DAKOTA - CSGTR 18Large number (up to 35%) of code failureso No patterns between sampled parameters and failed runs reportedo Noise might have an impact.o How to treat failed runs?Prohibitive computing time for some codeso Acceptable tend? Challenges Identified2nd General MUSA Project Meeting, 4. November 2021► Identifying governing uncertainties (weak correlation with FOMs).Common standard for post-processing Develop a harmonised approach to UASAKeep the physical understanding as a priority171810/11/202119Summaryo Huge progress made in tough conditions for the “joint” work.o Need to enhance exchange to move MUSA to a different level.- Discussion of issues and challenges to overcome- Sharing expertiseo MUSA third year might lead to insightful outcomesMUSA has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 847441.Thank you!20192010/11/202121Contact us at: contact@musa-h2020.euFollow us on LinkedIn: MUSA h2020 projectVisit our website: http://musa-h2020.eu/Subscribe to our newsletter!21

The MUSA Project: Halfway to the End

https://arpi.unipi.it/bitstream/11568/1110732/1/MUSA-CRP-2021.pdf

The MUSA Project: Halfway to the End

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