PREPARE. UPGRADE. VERIFY. COMMISSION. – YETS 2025 – 2026

By Kristiane Bernhard-Novotny

Today marks the beginning of the Year-End Technical Stop 2025–26 (YETS), a period in which CERN’s North Area shifts from high-intensity operation to an equally intense phase of maintenance and renewal. During the YETS, the North Area fills with activity: the only moment in the year when deep technical work, inspections and safety upgrades can be carried out without the constraints imposed by beam operation. Under the North Area Consolidation programme NA-CONS, specialists from across CERN now begin a carefully sequenced set of interventions designed to make the North Area safer, more reliable and better prepared for Run 2026 and the years that follow.

A major part of this winter’s work centres on safety, with the installation of the first fours fire-resistant partitions. These structures mark the beginning of the compartmentalisation of the North Area, creating safer zones, shorter evacuation paths and barriers that prevent smoke from travelling through tunnels, galleries and the tall shafts that connect the underground to the surface. Their purpose is simple: to give people time and space to evacuate, and to give firefighters a more controlled environment in which to intervene if it ever becomes necessary. The new fire doors, aspirating detection pipes and alarm speakers being installed across the complex complement this effort. Throughout the winter, tests and commissioning will verify that the new systems behave as intended, forming the backbone of a modernised safety architecture.