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The purpose of this paper is to assess the expected response of conventional and non-conventional quench detection sensors proposed for the ITER coils, and to be tested in the QUELL experiment in SULTAN. The assessment is based on simulation of thermohydraulic transients in the ITER coils for various operating conditions, and a tentative definition of the transfer functions of each sensor concept. It is shown that, for the investigated conditions, the co-wound voltage taps are more accurate than hydraulic systems and conventional voltage balance methods. The additional complication associated with the insertion of taps in the conductor is well offset by the low sensitivity to external disturbances.

This paper gives a brief description of the model commonly used to simulate thermo-hydraulic transients in Cable-in-Conduit Conductors (CICC's), in particular quench initiation and evolution. A discussion on the mathematical and physical characteristics of the system of equations is the starting point to assess the difficulties and advantages of methods used for the numerical solution of this class of problems. The crucial points in the simulation of quench are highlighted, they are associated with the fluid flow and the presence of moving boundaries. The implications for a selection of an optimally suited solution method are discussed.

Experiments on stability and quench propagation were performed on a NbTi hollow conductor test module allowing heat conduction only between adjacent layers, while the turns in a layer are thermally insulated (2-D winding). The measurements performed over a wide range of operating conditions were used as the experimental data-base for the comparison with the results of the simulations done using the quench analysis code SARUMAN. In the paper the experimental results are compared with the predictions of a 2-D version of SARUMAN, which show that the simulation is able to reproduce the general features of the quench propagation experiments.