Surrogates based multi-criteria predesign methodology of Sodium-cooled Fast Reactor cores – Application to CFV-like cores

Abstract

The Sodium-cooled Fast Reactor (SFR) core predesign process is commonly realized on the basis of expert advices and local parametric studies. As such, in-deep knowledge of physical phenomena avoids an important number of expensive simulations. However, the study space is explored only partially. To ease the computational burden metamodels, or surrogate models, can be used, to quickly evaluate the performances of a wide set of different cores, individually defined by a set of parameters (pellet diameter, fissile height...), in the study space. This paper presents the development of a simplified neutronics ERANOS reference core calculation scheme that is then implemented in the construction of the Design of Experiment (DOE) database. The surrogate models for SFR CFV-like cores performances are developed, biases and uncertainties are quantified against the CFV-v1 version. Global Sensitivity Analysis also allowed highlighting antagonist performances for the design and to propose two alternative core configurations. A broadened application of the method with an optimization of a CFV-like core is also detailed. The Pareto front of the seven selected performance parameters has been studied using eleven surrogate models, based on Artificial Neural Network (ANN). The optimization demonstrates that the CFV-v1, designed using Best Estimate codes, under given performance constraints, is Pareto optimal: no other configuration is highlighted from the Multi-Objective Optimization (MOO) study. Further MOO analysis, including a specific study on impact of new degrees of freedom, such as five Pu enrichments compared to two, or different pellet diameters have been performed. Additional configurations are then found by the surrogate models, improving simultaneously all performances of the CFV-v1 configuration.

Analysis of the impacts of homogeneous minor actinides loading in low void effect sodium fast reactor cores

“…This could not have been concluded by considering only the Doppler feedback and total sodium void worth. These results are consistent with the findings in (Fabbris et al, 2016). It can be observed in Table 5 that these results do not appear to depend on the transient considered.…”

“…3. This approach was previously used in (Fabbris et al, 2016) in combination with the more detailed CATH-ARE code (Emonot et al, 2011) and it was shown to introduce limited errors on the temperature profile in the core (below 5°C). Doppler and sodium thermal expansion profiles were similarly averaged over each medium, with the sodium and plenum sodium thermal expansion being added in an extra mesh on top of the fissile stack with zero power generation.…”

An optimization methodology for heterogeneous minor actinides transmutation

“…This factor is a measure of how well the meta-models reproduce the variance of the actual model. A meta-model will be deemed acceptable if the Q 2 estimator is higher than 0.95 in this context [15]. As it is shown in Table 3, it can be observed that all the estimators studied here exhibit higher than 0.95 Q 2 values, thus validating their good behavior.…”

Preliminary lightweight core design analysis of a micro‐transportable gas‐cooled thermal reactor

“…18 Considering the computational burden of Monte Carlo calculations, surrogate models are generated for neutronic design evaluation during the optimization process. 19 Nevertheless, safety concerns like material structural feasibility are not considered, 20 and a significant discrepancy is found in the void worth prediction. 21 Meanwhile, direct Monte Carlo simulations are used for some core optimization studies, in which the optimization objectives and corresponding input parameters are relatively less.…”