Multi-solid multi-channel Mithrandir (M3) code for thermal-hydraulic modelling of ITER Cable-in-Conduit Superconductors

We present a new multi-solid multi-channel (M3) thermal-hydraulic model for the analysis of the International Thermonuclear Experimental Reactor (ITER) Cable-In-Conduit Conductors (CICC). The model discretizes the cross section of an ITER CICC into M current carrying cable elements (e.g., the six last-but-one cabling stages-the petals), coupled with N hydraulic channels (e.g., the six petals + the central channel) and K non-current carrying solid components (e.g., the jacket of the CICC), with M, N and K arbitrary integers. Along each of the M + K solid components a 1D transient heat conduction equation is solved, whereas along each of the N channels three Euler-like 1D equations, derived from the conservation laws for compressible He flow, are solved. The resulting quasi 3D model, in which 1D equations are coupled by heat and mass transfer between the different CICC components, is implemented in the M3 code and validated against experimental results from the ITER Good Joint sample and the ITER Poloidal Field Conductor Insert Full Size Joint Sample. The new code is able to reproduce with good accuracy the measured temperature gradients on the CICC cross section, provided sufficiently accurate input data are available