Consolidation of personnel safety systems at CERN

Personnel Safety Systems provide prevention and mitigation barriers to protect personnel, users, equipment, and the environment against the risks associated with the operation of the CERN Accelerators and Experiments, such as Radiation, Fire, Gas and Oxygen Deficiency Hazards. Due to the obsolescence or ageing of technology, evolutions of the facility and the Safety rules, it is now time to consolidate existing safety systems to prepare the CERN complex for the coming decades. A dedicated program has therefore been launched to refurbish the Fire, Gas and Oxygen Deficiency Hazard Detection Systems, and to implement a new Voice Alarm and Evacuation System in the Large Hadron Collider, among others. The paper provides insight into the methodology used to define the appropriate safety levels required to pragmatically ensure the Safety of personnel and the environment in the facility. Lessons learned from 20 years of operation, interpretation of the legal framework, and the process of risk definition and reduction through preventive and protection measures will be discussed. The main ongoing projects and the challenges ahead of the teams in charge will also be briefly presented.