Evaluation and optimisation of occupational exposures in the hall of experiments of the ‘Laser Integration Line’ at CESTA

In the framework of research on inertial fusion, experiments on a reduced-scale prototype of the future Laser MegaJoule (LMJ) are planned in the ‘Laser Integration Line’ at CEA/DAM/CESTA. By 2005, part of these experiments will involve Deuterium–Tritium targets in which fusion reaction will result in radiation—mainly in the form of neutron flux and photon radiation from activated materials—that constitute a source of radiological exposure at the workplace. At the conception stage, an evaluation of the radiological exposures of occupational workers was performed. Different options for reducing these exposures have been studied. Results show that by modifying the composition of the staff or delaying the interventions, a reduction of the individual doses to the most exposed categories of employees from 2 to 50% to a factor 4 can be achieved, without increasing the total collective dose which can be further reduced by 10–25%. This study is a good illustration of how the ALARA principle can be implemented at the conception stage of an installation. Due to the low individual and collective exposures, the different options to reduce doses are more closely associated with staff and planning re-organisations. These options are characterised by a rather low cost and limited constraints of implementation.