Design and Analyses

Competences

The core design and analyses competence in the DAF is built upon the development of in-vessel components for magnetic confinement fusion (e.g. tokamak and stellarator), in particular the breeding blanket system (see Fig. 1). This system is in charge of breeding sufficient tritium (a virtually inexistent element in nature, which is one of the 2 elements of the fusion “fuel”, together with the naturally abundant deuterium), to ensure the tritium self-sufficiency in a nuclear fusion reactor. Not only that, the breeding blanket is in charge as well of the power production and extraction, which is later used to produce electricity and as first shielding element, protecting key systems behind it (mainly the superconducting magnets and the vacuum vessel.

The design and analyses expertise in the DAF group is focused on high temperature gas cooled core systems, in particular pressurized helium in the range 300 °C-600 °C. In this regard, the most common breeding blanket architecture developed in DAF for the EU DEMO has been the so-called Helium Cooled Pebble Bed (HCPB) breeding blanket, which features solid functional materials for tritium breeding (ternary lithium ceramics) and neutron multiplication (beryllium and beryllium alloys). However, the group competences has been extended to other alternative coolants (e.g. CO₂ and water) and different kinds of tritium breeder (many types of ternary lithium ceramics) and neutron multipliers (molten lead or lead alloys or solid lead alloys for high temperatures). Other than breeding blankets for fusion power plants, the group has decades of experience in design development and testing of Test Blanket Modules for ITER, in particular the HCPB-TBM.

Therefore, the multi-physics, multi-scale problem in the design development of a breeding blanket require a wide set of competencies in different engineering areas and the use of several computer numerical tools for fluid dynamics (CFD, e.g. ANSYS CFX) and finite element structural mechanics (FEM, e.g. ANSYS Mechanical). A simplified workflow is shown in the following picture. Starting from a set of functional and interface requirements for the system and some other boundary conditions (such as e.g. manufacturing, industrialization feasibility and costs), a first 3D model of the component to be analysed is built via CAD tools (i.e. CATIA V5) and imported in the computational tools used for the numerical analyses for the quick search of feasible configurations, as part of the first agile design cycle. After some first inputs from neutronics (Serpent, MCNP) analyses, fluid dynamic, thermal and mechanical analyses are performed by means of Finite Volume and Finite Elements codes. Once a sound, promising configuration is found, a detailed design cycle is performed with the objective to determine the key performance figures of the system. Here, and after neutronic inputs from MCNP analyses, massive thermal, thermo-hydraulic and thermo-mechanical analyses are performed. After obtaining the stress state of the system under several selected loading combinations, the mechanical compliance of the system is assessed in detail with selected nuclear Codes and Standards (RCC-MRx, SDC-IC, DDC-IC, ASME or the like). Both elastic and non-elastic design routes are employed for the determination of the fulfilment of the Codes and Standards.

The group is also involved in the engineering design and construction of complex experiments involving validation of predictive tools, proof-of-concept, feasibility and functional / manufacturing qualification testing of prototypical mock-ups.

Projects

The DAF team is strongly involved in the frame of the EUROfusion Consortium for the development of the so-called Helium Cooled Pebble Bed (HCPB) Breeding Blanket for the EU DEMO fusion power plant (Fig. 3-top), as well as in the ITER’s HCPB Test Blanket Module (HCPB TBM) development activities (Fig. 3-bottom). Also, the involvement in the EUROfusion Consortium

Since the establishment of the EUROfusion Consortium, an intense technical collaboration has been carried out together with the Budapest University of Technology and Economics (BUTE, Hungary), the Wigner Research Center for Physics (Wigner RCP, Hungary), the Research Center Řež (CVŘež, Czech Republic), The Institute of Plasma Physics of the Czech Academy of Sciences (IPP.CR, Czech Republic), the Research Center for Energy, Environment and Technology (CIEMAT, Spain) and industrial partners. For the HCPB-TBM development, KIT keeps a close colboration with the European Union domestic agency managing the European contribution to ITER, Fusion for Energy (F4E, Spain) and also industry.