The operations of decommissioning and repairing of installations are often difficult due to the lack of knowledge about the position of the contamination. In this sense, the gamma contamination is particularly difficult to define in a significant global background when the activities are relatively high. To be able to The operations of decommissioning and repairing of installations are often difficult due to the lack of knowledge about the position of the contamination. In this sense, the gamma contamination is particularly difficult to define in a significant global background when the activities is relatively high. able to