Speaker
Description
The CERN Neutrons to Gran Sasso (CNGS) facility was installed at CERN in 2002-2005 and operated from 2006-2012, sending a total of 18 E19 400GeV/c protons on target. The high dose rates expected in the target cavern, even years after the end of operation, several beamline elements were designed for remote handling. After installation and before the start of operation, the most critical handling and dismantling procedures were defined, performed on non-radioactive items, and documented to ensure the final dismantling would be “ALARA” concerning Radiation Safety, i.e, make dose to personnel as well as radioactive waste created As Low As Reasonable Achievable. At the end of operation, the CNGS target area was blocked off from the rest of the facility by an airtight shielding wall.
In 2025, to make space for the extension of the proton-driven wakefield acceleration (AWAKE) project, installed just upstream of the shielding wall, the CNGS Target Area Dismantling (CTD) works started. The CNGS target was removed in February 2026, and works will continue until the end of 2026, when the emptied, decontaminated CNGS target area will be handed over to the AWAKE project, allowing the start of the installation of AWAKE’s extended facility.
This paper shows the “ALARA” design and operational decisions made at the start and end of CNGS, and shows how they reduced dose-to-personnel and radioactive waste during the actual dismantling. We show the lessons learnt from the dismantling of CNGS’s most radioactive items, giving useful input to the design of future irradiation facilities and the procedures to dismantle them at end-of-life.