Calculation of Residual Dose Rates and Intervention Scenarios for the LHC Beam Cleaning Insertions - Constraints and Optimization

Abstract

Radiation protection of the personnel who will perform interventions in the CERN LHC Beam Cleaning Insertions is mandatory and includes the design of equipment and the establishment of work procedures. Residual dose rates due to activated equipment are expected to reach significant values such that any maintenance has to be planned and optimized in advance. Three-dimensional maps of dose equivalent rates at different cooling times after operation of the LHC have been calculated with the Monte Carlo code FLUKA. The simulations include a new method based on an explicit calculation of induced radioactivity and of the transport of the radiation from the radioactive decay. The paper summarizes the FLUKA-simulations for the Beam Cleaning Insertions and discusses the estimation of individual and collective doses received by personnel during critical interventions, such as the exchange of a collimator. The given example outlines the potential of the new doserate simulation method but also the potential and the need to optimize, in an iterative way, the design of components as well as the layout of the beam cleaning insertions. As result of a first benchmark test under realistic accelerator conditions measurements and simulations of residual dose rates for a collimator test recently performed at the SPS are presented.