Tolerance analysis for the outer-box of ITER feeder Coil Terminal Box & S-Bend Box

The ITER feeder systems connect the ITER magnet systems to the cryo-plant, power-supply and control system interfaces outside the cryostat. The main purpose of the feeders is to convey the cryogenic supply and electrical power to the coils as well as house the instrumentation wiring. The Feeder carries superconducting busbars, supercritical cryo-pipes and instrumental pipes from the CTB&SBB (Coil Terminal Box and S-Bend Box) to the coil. As one of the key components, the CTB&SBB houses the interconnection of the magnet systems with the cryo-plant, the power supplies, the data acquisition system and the local cryogenic components. So it is very important to keep enough installation accuracy for CTB&SBB key components. This paper presents the tolerance analysis of CTB&SBB box in three-dimensional model. The main objective of this analysis is to find out the critical dimension for the assembly requirements, evaluate the effect of design tolerance and limits of tolerance values for the key dimension of CTB&SBB box. The model and method do not only consider the assembly sequence as well as the assembly reference, also the sensitivity caused by different tolerance. Based on the results, the assembly performance of CTB&SBB box has been studied and tolerance values of detail design confirmed.