Methodology for the improvement of the AINA Code wall-model applied to DEMO WCPB blanket

Abstract The present work describes and supports the methodology for the improvement of the wall model developed in AINA and its specific application to the Japanese DEMO Water Cooled Pebbled Bed. The set-up and application of this approach aims to obtain robust models by estimating the behavior of the studied systems as accurately as possible. These systems are represented in a simplified way. This requires the computation of a 3D radiation transport which has been carried out by means of MCNP6.1, ADVANTG and thermal-hydraulic calculations using ANSYS ® Fluent ® . Several CFD mesh typologies and discretizations have also been employed to test the Richardson theorem. In addition, 1D simplified models have also been created and optimized for their usage in AINA code. The temperature distribution also shows good agreement (within 7%). In some cases the simplified models have not behaved in a conservative manner compared with the outcomes obtained for the 3D models. This observed absence of conservatism is intrinsic to the 1D approach. To cope with these effects, scaling functions have been determined as a ratio between the most conservative radial temperature distribution – computed by fully detailed 3D CFD – and the 1D simplified model. The scaling functions will be applied to the AINA computed wall temperature distribution. To conclude, the determination and coherence of the result obtained using independent tools and approaches, ANSYS ® Fluent ® vs AINA thermal-hydraulic routines, lead us to recommend the proposed methodology.