Abstract
Magnetohydrodynamic (MHD) phenomena, due to the interaction between a magnetic field and a moving electro-conductive fluid, are crucial for the design of magnetic-confinement fusion reactors and, specifically, for the design of the breeding blanket concepts that adopt liquid metals (LMs) as working fluids. Computational tools are employed to lead fusion-relevant physical analysis, but a dedicated MHD code able to simulate all the phenomena involved in a blanket is still not available and there is a dearth of systems code featuring MHD modelling capabilities. In this paper, models to predict both 2D and 3D MHD pressure drop, derived by experimental and numerical works, have been implemented in the thermal-hydraulic system code RELAP5/MOD3.3 (RELAP5). The verification and validation procedure of the MHD module involves the comparison of the results obtained by the code with those of direct numerical simulation tools and data obtained by experimental works. As relevant examples, RELAP5 is used to recreate the results obtained by the analysis of two test blanket modules: Lithium Lead Ceramic Breeder and Helium-Cooled Lithium Lead. The novel MHD subroutines are proven reliable in the prediction of the pressure drop for both simple and complex geometries related to LM circuits at high magnetic field intensity (error range ±10%).
Highlights
It should be stressed that the HCLL Test Blanket Modules (TBMs) mock-up can be considered by all means a stateof-the-art scaled-down integrated effect test (IET) facility since it represented all relevant isothermal MHD phenomena but for a skewed magnetic field that, is unlikely to be achieved before the start of the experimental TBM phase in ITER
Considering that the RELAP5 Flow Channel Inserts (FCIs) model is based on experimental outcomes that usually include these contraction/expansion contributions, the discrepancy of ∆p3D with the experimental data in the present test case is because of the cross-section variation being taken into account twice by RELAP5: with the activation of the flow channel insert model and the cross-section restriction model
A new module for the best-estimate SYS-TH code RELAP5/MOD3.3 has been developed at Sapienza, University of Rome, allowing the program to model MHD pressure drop in liquid metal circuits
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Codes could enable the efficient and quick simulation of the blanket piping network level but, currently, they have limited or non-existent MHD capability This kind of codes are crucial for the assessment of thermal-hydraulics phenomena occurring within complex nuclear systems. Pursuing the quest for the realization of a MHD system-level tool, a novel code called MHD-SYS has been developed that features models for the simulation of multiple electrical-coupled ducts and heat transfer for basic layouts, whereas coupling with CFD codes is employed to supply the system code with reliable input data for the behaviour of the flow in complex geometrical elements [17]. The aim of this work is to present the first phase of the development of a comprehensive and robust numerical tool able to handle all the fundamental MHD effects occurring in a LM breeding blanket, ranging from pressure loss to mass transport, in order to support fusion reactor design. A verification and validation (V&V) procedure is reported to assess the confidence of our numerical method against the benchmark of high-quality numerical simulations and experimental data, as suggested by Ref. [20]
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