Abstract of PARSUM4C Project

HLST resources are requested to parallelize from scratch and optimize the Cryogenic Circuit Conductor and Coil (4C) code, recently developed at Politecnico di Torino, Italy. According to the literature, 4C is the most widely and successfully validated code available at present for the analysis of thermal-hydraulic (TH) transients in a tokamak superconducting magnet system and related cryogenic circuit.

The 4C code includes a cryogenic circuit module (Modelica language), a module for the coil casing (FreeFem++ environment) and two modules (Fortran) for the winding and the casing cooling channels, respectively. As profiling shows that the bottleneck is in the Fortran modules, we especially aim at parallelizing those to reduce the execution time, at optimizing the solver routines and at reducing the memory needs of the code.

The potential impact of this project on the European fusion program is at least twofold:

1. Fast (and reliable) TH system codes could improve and extend the scope of the assessment of the compatibility of any desired plasma scenarios with the safe and efficient operation of the magnet system. In the present option, low critical temperature superconductors cooled by supercritical helium will be used for the DEMO magnets, as it is already the case for several existing and future fusion experiments (e.g., ITER, JT60-SA, KSTAR, EAST), but heat loads, e.g. of nuclear origin, may erode the very small temperature margin (0.7 K in ITER) available between the operation temperature (~4.5 K in ITER) and the current-sharing temperature, where the superconducting properties start to be lost and the quench of the magnet is initiated with potentially serious consequences if unprotected.
2. The proposed parallelization and optimization of the 4C code, originally developed in the framework of an EFDA contract, could consolidate the European leadership in the field of TH modelling of the tokamak superconducting magnet system.