Objectives and status of the oecd/nea sub-group on uncertainty analysis in modelling (uam) for design, operation and safety analysis of sfrs (sfr-uam)

International audienceAn OECD/NEA sub-group on Uncertainty Analysis in Modelling (UAM) for Design, Operation and Safety Analysis of Sodium-cooled Fast Reactors (SFR-UAM) has been formed under the NSC/WPRS/EGUAM and is currently undertaking preliminary studies after having specified a series of benchmarks. The incentive for launching the SFR-UAM task force comes from the desire to utilize current understanding of important phenomena to define and quantify the main core characteristics affecting safety and performance of SFRs. Best-estimate codes and data together with an evaluation of the uncertainties are required for that purpose, which challenges existing calculation methods. The group benefits from the results of a previous Sodium-cooled Fast Reactor core Feed-back and Transient response (SFR-FT) Task Force work under the NSC/WPRS/EGRPANS.Two SFR cores have been selected for the SFR-UAM benchmark, a 3600MWth oxide core and a 1000MWth metallic core. Their neutronic feedback coefficients are being calculated for transient analyses. The SFR-UAM sub-group is currently defining the grace period or the margin to melting available in the different accident scenarios and this within uncertainty margins.Recently, the work of the sub-group has been updated to incorporate new exercises, namely, a depletion benchmark, a control rod withdrawal benchmark, and the SUPER-PHENIX start-up transient. Experimental evidence in support of the studies is also being developed

Current Status and Perspectives of the OECD/NEA sub-group on Uncertainty Analysis in Modelling (UAM) for Design, Operation and Safety Analysis of SFRs (SFR-UAM)

International audienceAn OECD/NEA sub-group on Uncertainty Analysis in Modelling (UAM) for Design, Operation and Safety Analysis of Sodium-cooled Fast Reactors (SFR-UAM) has been formed under the NSC/WPRS/EGUAM to check the use of best-estimate codes and data. This work comes from the desire to design reactors with improved safety performance while preserving a sustainable source of energy at a rather low cost. Two SFR cores are being studied a large 3600MWth oxide core and a medium 1000MWth metallic core. In order to assess tools being used for studying these cores, various sub-exercises have been set up for what concerns neutronics with cell, sub-assembly, super-cell and core benchmarks under steady state conditions either at BOL conditions or at EOEC. A sub-assembly depletion benchmark is being set up before going into full core calculations with depletion. Since the objective is to define the grace period or the margin to melting available in the different accident scenarios and this within uncertainty margins, uncertainties of different origins (methods, neutronics, thermal-hydraulic, fuel behavior) once identified and evaluated will be propagated through. In order to ensure validity to these exercises, the sub-group incorporates some experimental validations on neutronics, thermal hydraulics, fuels and systems. This will be done with experiments from IRPhE et ICSBEP, SEFOR, THORS and the SUPER-PHENIX start-up transient programme