I.-In compliance with the principle of optimisation mentioned in 2° of Article L. 1333-2 of the Public Health Code, the employer shall ensure that, as far as possible, the exposure of workers involved in a radiological emergency is kept below the occupational exposure limit values set in 1° of Article R. 4451-6.
II -Where the conditions of intervention do not allow it, the employer shall ensure that their exposure is kept below the reference level set in I of Article R. 4451-11.
III -In exceptional situations, to save lives, prevent serious radiation-induced health effects or prevent the occurrence of catastrophic situations, the employer shall ensure that the individual exposure of the worker concerned remains below the reference level laid down in II of Article R. 4451-11.