NEW CAPABILITIES OF CERES® CBRN-E DECISION SUPPORT TOOL IN THE FIELDS OF EXPLOSION MODELLING AND SOURCE TERM ESTIMATION Luc Patryl 1 , Emmanuel Lapébie 2 , Sarah Hank 3 , and Patrick Armand 1 1 CEA, DAM, DIF, F-91297 Arpajon, France 2 CEA, DAM, F-46500 Gramat, France 3 RS2N, F-83640 Saint-Zacharie, France Abstract: Developed at CEA since 2008, CERES® CBRN-E is a computational tool designed for crisis management in case of accidental, malevolent or terrorist releases of hazardous radiological, chemical or biological materials. More precisely, CERES® computes atmospheric dispersion in complex environments including buildings (industrial sites or urban areas), assesses the health consequences of the toxic releases on the population and first responders, and delivers operational results (e.g. danger zones, intervention zones...) in less than 15 minutes to rescue teams and decision makers. CERES® is a flexible modular platform, thus capable to integrate both simplified and advanced models adapted to the description of the scenario (leakage from storage, evaporation from a pool, fire…), the AT&D of the hazardous material and the CBRN impact evaluation. This paper aims at discussing two recent developments in CERES®. The first one relates to high-Mach source terms simulation in case of an explosion preceding the toxic dispersion. The near-field unstationary source terms generated by energetic reactions are included in CERES® using either analytical relations (gathered in the so-called D 2 R 2 modules) derived from multiphase pre-computations or a direct coupling between the pre-established transient results of the HI2LO code (a CFD model able to deal with the transition from high to low-Mach number flows) and CERES®. These models provide the source term geometry and the noxious material granulometry and spatial distribution after the explosion, taking into account the presence of the buildings in the simulation domain. The second development consists in the implementation in CERES® of a simple method for source term estimation using in-field sensors measurements. In a first step, retro-plumes are propagated individually from each of the detectors. In a second step, the possible locations of the source and associated releases rate are determined by retro-plumes overlapping. For both developments, the paper gives more details about the methodology and the validation of the new modules based on experimental data. Key words: CERES® CBRN-E, modelling and decision support, explosion modelling, high-Mach to low-Mach flow, source term estimation. INTRODUCTION CERES® CBRN-E is an operational computational tool devoted to hazmat atmospheric dispersion modelling and impact assessment, gathering several source term models, various dispersion approaches (from Gaussian puff to advanced 4D flow and dispersion computations) and health consequence modules adapted respectively to R-N, C or B noxious agents (Armand et al., 2013). CERES® is able to compute atmospheric dispersion in complex environments including buildings (industrial sites or urban areas), assess the health consequences of the toxic releases on the population and first responders, and deliver operational results (e.g. danger zones, intervention zones...) in less than 15 minutes to rescue teams and decision maker. This paper aims at di scussing two recent developments in CERES®. The first one relates to high-Mach source terms simulation in case of an explosion preceding the toxic dispersion. The second development consists in the implementation in CERES® of a simple method for source ter m estimation using in-field detectors measurements. HIGH-MACH SOURCE TERMS Transport and dispersion codes usually run under the assumption of uncompressible flows. This can be translated into maximum local Mach number requirements. The local Mach number of a flow is defined as us/as, us being the particle velocity and as the local sound speed. Rankine-Hugoniot formulas applied to blast waves (Dewey, 2006) provide a relation between the local Mach number of the flow and density ratios. This relation applied to air (gamma = 1.4) shows that a local Mach number of 0.1 (particle velocity of 35 m/s) corresponds to a density increase of 11%, which could be set as a reasonable limit for the uncompressible flow assumption. Other authors use a threshold value of 0.3 (local Mach number, the particle velocity being 109 m/s) which is arguable since it corresponds to a 36% density increase. On the contrary, many source terms begin with high Mach flows. This is obviously the case both for source terms involving high explosives (for instance air strikes on chemical facility targets, warheads with chemical or biological payloads, dirty bombs...) and also for many accidental releases from pressurized containers. It is thus not mathematically and physically correct to connect such source terms to uncompressible codes.