THE QUELL EXPERIMENT AS A VALIDATION TOOL FOR THE NUMERICAL CODE GANDALF

One goal of the QUELL experiment is the validation of numerical codes for the simulation of thermo-hydraulic transients in Cable-in-Conduit Conductors with Central Channel (C-5). The validation of Gandalf has f ocused on 17 quench propagation runs. In general, the good global agre ement of the simulations with the experiments-the standard deviation i s in the range between 5% and 25%-as well as the good computer perform ance qualifies Gandalf as a reliable engineering tool. One limitation of the simplified two-flow model implemented in Gandalf is that it ten ds to overestimate the quench propagation, and hence the helium pressu re increase, in the initial phase of the quench evolution, and to unde restimate them in the final phase. In standard quenches this limitatio n can be overcome by full two-flow modeling (Mithrandir code). Two fur ther problem areas have been identified: the high sensitivity (in comm on with full two-flow modeling) to conductor parameters, if the coil i s operated at low temperature margin, and the lack of accuracy when us ing simplified hydraulic boundary conditions. (C) 1998 Elsevier Scienc e Ltd.