Figure 1. The CRANEbot system, developed at CERN, lifted a prototype VAX M1 module and installed it into a mockup of the forward shielding in the ATLAS cavern, testing for the real manoeuvres that will take place during Long Shutdown 3. Credit: BE-CEM-MRO team.
By Oliver Boettcher, Sergio Di Giovannantonio and Florence Thompson (CERN)
A remote-handling test of the VAX M1 vacuum module has been successfully carried out in the ATLAS cavern using the CRANEbot robotic system, developed at CERN.
The VAX is the vacuum system for the beamline of the ATLAS and CMS experiments and will enable vacuum to be maintained during HiLumi operation. It is formed of three modules: two sector valve modules called M1 and M3, with a pumping module called M2 in the middle.
In Long Shutdown 3, a period of time when the LHC will be switched off for a number of years, the VAX modules will be installed for the first time, inside the forward shielding sitting around 18 metres away from the collision point at both experiments.
Due to the radiation and tight space limitations in this region, every VAX module developed for the HiLumi LHC is specially designed to be installed and removed remotely. Engineers have developed, repeatedly tested, and improved dedicated remote handling equipment and methods to perform all required manoeuvres effectively for the installation and maintenance of these modules.
Following an extensive surface test campaign and subsequent developments for the installation of all VAX modules, the operation has now taken place in the cavern itself, marking the first remote installation and removal test of M1 in the real ATLAS environment.
To closely replicate real maintenance scenarios, a reduced test environment, involving a mock-up of the ATLAS shielding space, focusing on M1 remote operation was brought from the surface to the ATLAS cavern. The mock-up was inclined with 0.7° angle to mimic the real forward shielding position.
Figure 2. The test simulated the installation of the VAX M1 module into the forward shielding, and its connection to the beam line. Credit: BE-CEM-MRO (left) and Dusan Soskic / CERN (right).
The entire operation was remotely controlled in close coordination between robot and crane operator from a restricted-view area of the ATLAS cavern, deliberately chosen to replicate the conditions of a potential radiation-safe control location. This approach enabled engineers to rigorously test the required remote operation for M1 under realistic cavern constraints, which was a key requirement for all future VAX maintenance interventions.
Figure 3. Engineers operated the CRANEbot from a platform in the ATLAS cavern, to simulate remote operation. Credit: Florence Thompson / CERN (left), BE-CEM-MRO team (right).
For the first phase of the test, the CRANEbot system was connected to the hook of the cavern’s overhead crane and engineers used the guidance of two movable cameras extended from the CRANEbot to carefully lift the vacuum module and precisely install it onto its support within the mock-up structure. This manoeuvre only allows 3 mm deviation in the horizontal plane from the centre position to correctly position the guidance pins into their spheres; extremely precise considering that CRANEbot and M1 were hanging 20 metres below the crane.
Figure 4. Robot camera POV during M1 positioning onto its support. Credit: BE-CEM-MRO team.
In the second phase of the operation, lifting spreaders were removed and the CRANEbot was placed very close over M1. Using a specially designed tool (the VAX screwdriver) the robot manipulated several mechanisms to correctly position the M1 flange and to tighten the chain clamp of the module simulating the full operation of connecting M1 to the beamline.
The entire installation sequence was subsequently repeated in reverse to reproduce the module removal procedure.
Figure 5. M1 chain clamp tightening using the VAX screwdriver installed on the CRANEbot. Credit: BE-CEM-MRO team.
Despite the confined space, limited visibility, and crane-induced oscillations, targeted developments to the robot and operating methodology enabled smooth and reliable performance. Custom-designed tooling, together with purpose-built user and robot interfaces, provided precise control of the robot and ensured the required installation accuracy.
Similar manoeuvres and testing will take place in CMS but adapted to its specific needs. Last year, during the end-of-year shutdown, a different robotic solution was deployed there to perform in-situ machining of the rotating shielding, creating the additional space required to accommodate the vacuum modules.
This successful test represents a significant step forward for remote maintenance in high-radiation environments and highlights the strong collaboration between robotics, vacuum, survey, and transport teams, within the framework of the HiLumi LHC Project Collider-Experiment Interface and Vacuum and Work Packages.
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