Processes and Tools to Manage CERN Programmed Stops Applied to the Second Long Shutdown of the Accelerator Complex

The preparation and follow-up of CERN accelerator complex programmed stops require clear processes and methodologies. The LHC and its Injectors were stopped in December 2018, to maintain, consolidate and upgrade the different equipment of the accelerator chain. During the Long Shutdown 2 (LS2), major projects were implemented such as the LHC Injectors upgrade and the LHC Dipoles Diodes consolidation. The installation of some equipment of the HL-LHC project took also place. This paper presents the application to the LS2 of the processes and tools to managed CERN programmed stops: it covers the preparation, implementation and follow up phases, as well as the KPIs, the tools used to build a coherent schedule and to follow up and report the progress. The description of the methodology to create a linear schedule, as well the construction of automatised broken lines and progress curves are detailed. It also describes the organizational set-up for the coordination of the works, the main activities and the key milestones. The impact of the COVID-19 on the long shutdown will be described, especially the strategy implemented to minimise its consequences.