In the High Luminosity Large Hadron Collider (HL-LHC) era, the intensity of the circulating bunches will increase to 2.2e+11 protons per bunch, almost twice the nominal LHC value. Besides detailed studies of known and new failure cases for HL-LHC, it is also required to investigate failures beyond nominal design. A consequence of such failures can be the impact of a large number of high-energy particles in one location, resulting in a significantly increased dam- age range due to an effect called hydrodynamic tunnelling. This phenomenon is studied by coupling FLUKA, an energy deposition code, and Autodyn, a hydrodynamic code. This paper presents the simulated evolution of the deposited energy, density, temperature and pressure for the impact of the HL-LHC beam on a graphite target. It then computes the resulting tunnelling range and finally compares the outcome with previous studies using LHC intensities.

The Future Circular Electron-Positron Collider (FCC-ee) is CERN's leading proposal for the next generation of energy-frontier particle accelerators. To reach integrated luminosity goals, it aims to be operational for minimum 80 % of the scheduled 185 physics days each year. For comparison, the Large Hadron Collider (LHC) achieved 77 % in 2016-2018. There are additional challenges in the FCC-ee due to its size, complexity and ambitious technical objectives. Availability is therefore a significant risk to physics deliverables. This paper presents the framework used to analyse availability and luminosity in the FCC-ee. To showcase its capabilities, first, a top-level system deconstruction reveals several key relationships for the Radio Frequency (RF) system. Second, two proposed technologies are simulated to overcome constraints in the Z, W operation cycle. Of these, pre-polarised bunch injection (PPBI) shows tremendous advantage for shielding integrated luminosity from a challenging availability environment.