Quality Assurance of the 13-kA Superconducting Magnet Circuits Consolidation of the LHC at CERN

The Large Hadron Collider (LHC) is designed to operate at a nominal energy of 14 TeV in the center of mass. Following the incident that occurred in 2008, LHC operated at intermediate energies ranging from 7 to 8 TeV to avoid any further risk of failure. The first long shutdown (LS1) of the LHC machine started in February 2013 and was mainly triggered by the consolidation of the 13-kA superconducting magnet interconnections. The key element of the consolidation consists of adding copper shunts on the LHC splices to ensure the electrical continuity in the 13-kA resistive part of the circuits. The consolidation work was organized in the form of a “train” of specialized teams working in sequence, altogether consisting of about 100 technicians, including production, supervision, and quality assurance. A Large Magnet Facility Quality Assurance (LMF-QA) team was created in the beginning of 2012 to overview, plan, and organize the quality management of the consolidation train for LS1. For 1695 interconnects, each containing six 13-kA splices, of which two belong to the main dipole circuit and four to the main quadrupole circuits, almost 14 000 interventions and quality checks were planned and performed for the 10 170 magnet-to-magnet splices. This careful monitoring of the performance indicators allowed a constant improvement of the production quality. The final analysis confirmed that the collected data are in a confidence interval of 99.5 ± 0.3 with a confidence level of 99%. With the LMF-QA data analysis and the Electrical Quality Control contribution, the LHC splices are fully characterized at room temperature. This paper presents a general overview of the quality assurance activity and provides a concise description of the method adopted by the LMF team throughout the LS1 project.