Like other industrial plants, the infrastructure needed to operate CERN’s large accelerators emits noise, especially when the accelerators are operational or undergoing maintenance. The main sources of noise at CERN are cryogenic installations, transformers, compressors, pumps, cooling towers and HVAC systems.
In 2019, the Laboratory adopted an environmental noise reduction policy. The corresponding implementation strategy was agreed upon with the competent local authorities. This policy was established taking, as a baseline, the noise generated in 2018 by CERN’s installations. It also sets out both preventive and corrective measures to avoid exceeding the existing noise levels. Since the baseline was defined, CERN has carried out yearly noise measurement campaigns in the vicinity of some 120 locations, during both daytime and night-time, to verify that the noise levels remain within the limits set.
As part of implementing CERN’s environmental noise policy, a project called NuiSoCERN has been launched in collaboration with HEPIA in Geneva (Haute école du paysage, d’ingénierie et d’architecture de Genève). The project involves developing 3D acoustic models for each CERN site in order to study potential improvements and plan for the future.
For this purpose, sources of noise, such as existing noisy infrastructure and equipment, are characterised, based on the ISO 9614-3 standard. The noise source data is then processed by a 3D georeferenced modelling software, CadnaA, which computes CERN’s environmental noise footprint with respect to the nearest residential areas. Mitigation measures are defined where needed, based on the results of the modelling.
Priority is given to reducing the noise at the source, for example by modifying the installations or replacing noisy equipment with quieter equipment. Patrols are also organised to detect malfunctioning equipment early. Should it prove impossible to make the modification for technical reasons, CERN instead implements mitigation measures, such as noise barriers and silencers. An example of this is the installation of two large noise silencers on the cryogenic exhaust at LHC Point 2 in 2020 prior to the start of the cool-down of the accelerator. The efficiency of these measures was confirmed by continuously measuring noise levels during the entire cool-down campaign.
Similarly, acoustic screening solutions have been implemented on the outlet ventilations of the new data centres located at LHC Point 8 (see below).
An infographic about noise is coming soon. Stay tuned!
This article is about environmental noise. For information on occupational noise, please consult the General Safety Instruction for protection of workers against noise (GSI-SH-4).
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This article is a part of the series “CERN’s Year of Environmental Awareness”.