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The torodial‐field (TF) magnet coils for ITER are made by superconducting cable in conduit conductors (CICC) using 316LN for the conduit. Compaction of the conduit and heat treatment to react the Nb3Sn material are one of the main steps during manufacture of this type of conductor. Therefore a systematic investigation was done to examine the influence of compaction and heat treatment on the mechanical behavior of this material. Several 316LN tubes were deformed to smaller radii to obtain different stages of compaction, followed by a heat treatment. From these tubes flat specimen were made by electron‐discharge‐machining (EDM) for tensile tests. The results are reported and compared to former tests on samples either compacted or heat treated.

Several prototype Cable‐In‐Conduit‐Conductors (CICC) for the superconducting EDIPO (Efda DIPOle) revealed a degradation of their critical current (Ic) increasing with each loading cycle. The strong Lorentz‐forces during operation in combination with the limited support of the single strands against these forces are thought to be the cause of the permanent degradation of the brittle Nb3Sn superconductor from which the multi‐stranded CICC are made. In summer 2006 EFDA started to explore the possibility to remedy the Ic degradation by solder‐filling the conductor in order to mechanically stabilize the twisted‐strand cable inside the conduit. This solution was not considered as the main one, but as an emergency solution to be applied to the completed magnet, should every other option fail. The solder‐filling approach was previously applied with success in some cases. Some issues, however, needed to be clarified before this solution could be proposed for the EDIPO project. The most important among them are the choice of solder material, details of the solder filling process, and the thermo‐mechanical implications of a solder‐filled, high‐field, high‐current cable. This work, being reported here, made use not only of simulation but also of experiments, such as the mechanical testing of solder filled cables at cryogenic temperatures.