A priori prediction of phase stability of materials is a challenging practice, requiring knowledge of all energetically competing structures at formation conditions. Large materials repositories-housing properties of both experimental and hypothetical compounds-offer a path to prediction through the construction of informatics-based, ab initio phase diagrams. However, limited access to relevant data and software infrastructure has rendered thermodynamic characterizations largely peripheral, despite their continued success in dictating synthesizability. Herein, a new module is presented for autonomous thermodynamic stability analysis, implemented within the open-source, ab initio framework AFLOW. Powered by the AFLUX Search-API, AFLOW-CHULL leverages data of more than 1.8 million compounds characterized in the AFLOW.org repository, and can be employed locally from any UNIX-like computer. The module integrates a range of functionality: the identification of stable phases and equivalent structures, phase coexistence, measures for robust stability, and determination of decomposition reactions. As a proof of concept, thermodynamic characterizations have been performed for more than 1300 binary and ternary systems, enabling the identification of several candidate phases for synthesis based on their relative stability criterion-including 17 promising C15 -type structures and 2 half-Heuslers. In addition to a full report included herein, an interactive, online web application has been developed showcasing the results of the analysis and is located at aflow.org/aflow-chull .

While the ongoing search to discover new high-entropy systems is slowly expanding beyond metals, a rational and effective method for predicting "in silico" the solid solution forming ability of multi-component systems remains yet to be developed. In this article, we propose a novel high-throughput approach, called "LTVC", for estimating the transition temperature of a solid solution: ab-initio energies are incorporated into a mean field statistical mechanical model where an order parameter follows the evolution of disorder. The LTVC method is corroborated by Monte Carlo simulations and the results from the current most reliable data for binary, ternary, quaternary and quinary systems (96.6%; 90.7%; 100% and 100%, of correct solid solution predictions, respectively). By scanning through the many thousands of systems available in the AFLOW consortium repository, it is possible to predict a plethora of previously unknown potential quaternary and quinary solid solutions for future experimental validation.

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The main purpose of this benchmark paper is to study and compare point and spatial neutronic approaches used to calculate ULOF and UTOP transients in sodium cooled fast reactors. A second objective is to compare deterministic and Monte Carlo calculations with two different calculation codes. The first one is based on a deterministic (discrete ordinate S N) approach, using tabulated self-shielded cross sections, where the core reactivity and the power shape distribution are evaluated at each time step of the transient calculation. The second model relies on the Transient Fission Matrix (TFM) approach, condensing the response of a Monte Carlo neutronic code in time dependent Green functions characterizing the local transport in the reactor. This second approach allows a fast estimation of the reactivity and of the flux redistribution in the system during the transient with a precision closed to that of the Monte Carlo code. Both models have been coupled to the thermalhydraulics and applied on an ASTRID representative assembly. This application case is supposed to be sensitive to power redistributions. A second comparison between spatial kinetics and point kinetics calculations has been led to study this point. Finally we obtain a good agreement between spatial and point kinetics on ULOF and UTOP calculations, while some discrepancies are observed between the TFM and the S N approaches on the power level stabilization, due to difference on the feedback estimation in both models.

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