Potential failures and hazards in superconducting magnet systems for fusion reactors

One of the major components in a fusion reactor for which a safety analysis must be carried out is the magnet system. An attempt is made to provide a systematic answer to the hazard potential of superconducting magnets for fusion. Event trees are developed, demonstrating the predictable behavior in all cases. It can be seen that usual failure events cause only a temporary shutdown of the magnet system without damage. Less likely accidental events will lead to single-current arcs with moderate internal damage of a single coil. Only sudden complete rupture of a turn can be followed by a multiple-current arcing resulting in a very high power arc with a certain probability of burning through the coil case, thus damaging other reactor components before extinction. Missile generation of winding parts can only occur in the very hypothetical case of simultaneous rupture of the winding at a sufficiently large distance apart. 19 refs