Speaker
Description
One of the tasks of the Radiation Protection (RP) group at CERN is to provide forecasts on the radiological classification of the areas within the main LHC experiments (ALICE, ATLAS, CMS, LHCb) and forecasts on the residual dose rates due to the induced radioactivity from the proton-proton and ion-ion collisions. These forecasts can be performed due to a knowledge of the expected luminosity to be delivered. Therefore, the related irradiation profiles will contain real luminosity data from previous operation periods and forecasts for future operation periods.
These predictions are essential to organize in advance the activities in the caverns as the LHC detectors are being upgraded during the Long Shutdown 3 that started on June 29, 2026. These activities will require multiple and prolonged interventions in residual radiation environments and the handling of activated detector components of different nature. An optimization of the dose to personnel will be needed for each intervention.
The RP studies have in common that FLUKA simulations are employed, and there are times in which they can be time consuming. Different approximations on the irradiation profiles could have a significant impact on the radiological quantities but this is not necessarily the case. In order to assess the impact of such approximations on the quantities while avoiding to perform new simulations when the irradiation profile has been changed, the RP group has developed a tool with which the ratio of two radiological quantities is given for each contributing radionuclide when comparing the two irradiation profiles. This results in a set of scaling factors that can be applied for each radionuclide so that the radiological quantity in the new situation can be computed.
Examples of the application of the tool will be presented. These include assessments on proposed changes to the operational schedule of the LHC such as the High Intensity Test period in the 2 weeks before the start Long Shutdown 3 as well as scaling factors for gamma spectroscopy results of activation samples that have been installed in the LHC experimental cavern for a limited period of time in view of the radiological classification of detector or infrastructure components.
In this communication we will present the workflow followed by the RP when providing the irradiation profiles, their consequences in the RP studies and how the tool optimizes the general workflow.
In addition, the first results and observations from the first months of Long Shutdown 3 will be presented.
| Topics | T5. Induced radioactivity and decommissioning |
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