# A New Radiological Risk Containment Procedure in Potentially Contaminated Areas
## 2 Materials and Methods  
### Background and Methodology  
The origin of a radioactive contamination is an aspect of extreme importance, that also influences the methods of carrying out the investigation. Its knowledge, in fact, often allows us to know, or hypothesize with reasonable certainty, the radiometric characteristics of the contamination itself [16]. However, it is difficult to make an exhaustive list of the various possible sources of radioactive contamination of a generic site. In many cases, the origin of the contamination is not known and it is indeed the investigation itself that must help to understand it. In a situation in which it is assumed or has been ascertained an unlawful activity regarding the dumping of waste, the origin of a radioactive contamination can be linked to one or more of the following causes:  
* Trafficking or disposal of real radioactive sources, i.e., metal objects, sealed, even very small in size but with very high radioactivity values, possibly still contained within metal shields;
* Traffic or disposal of radiocontaminated materials, that is, bulk material of various origins (metal pieces, foundry slag, demolition rubble, medical waste, etc.) that at different moments of its production cycle came into contact with unsealed radioactive materials;
* Traffic or disposal of products or residues deriving from particular work activities involving the use of radioactive materials of natural origin (NORM);
* Traffic or disposal of nuclear fuel cycle materials. In addition, the identification of the involved radionuclides is, from a technical point of view, the main question to define when planning. The nature of the radionuclides themselves, as well as their physical state, decisively influence the carrying out of the investigation. As a matter of fact, the sampling protocols, the choice of measurement techniques to be used, as well as the overall rating criteria depend on it. The innovative radiological risk containment procedure reported in the present paper is based on the preventive verification of environmental radioactivity levels through measurements of the absorbed dose rate, with the aim of:1. Estimating the environmental radioactivity background level in the area of interest, through absorbed dose rate measurements performed at a height of 1 m above the ground level. For this purpose, the portable battery charged pressurized ion chamber survey meter, LUDLUM 9 DP, 0-50 mSv/h dose rate range, 60 keV-1.25 MeV energy range, was employed [17]. All readings, at a distance of 1 m from each other, were performed through a transect that covered the region of interest. Ten readings, of 600 s each, were taken at each point of the transect and the average was recorded [18]. 2. Assessing the presence (if any) of hot spots, by recording radiometric anomalies. In particular, the radiometric anomaly, \(\Delta\), is defined as a significant increase in the environmental radioactivity background level, outside the acceptability value of the absorbed dose rate given by [19]: \[\Delta\ \left(nGy\ h^{-1}\right)=\dot{D}_{\mathit{bkg}}+3\ \sigma_{\mathit{bkg}}\] (1) where \(\dot{D}_{\mathit{bkg}}\) is the average value of the environmental background dose rate and \(\sigma_{\mathit{bkg}}\) its standard deviation. 3. Performing gamma spectrometry measurements to identify the radionuclides that generate those anomalies. For this aim, the portable Canberra InSpector 1000 NaI spectrometer was employed [20]. It is a high-performance detector, designed to be used in all types of environmental conditions, with a high-resolution LCD color display, clearly visible from bright sunlight to night conditions. For applications requiring flexible positioning of the detector relative to the object being inspected, the detector can be detached from the instrument body and placed in any position or narrow gap. This greatly increases the probability of detecting small amounts of radiation and precisely locating sources by reducing the measurement distance.