A computational model for estimation of 226 Ra and 228 Ra concentrations in sludge from petrol exploitation, based on radiation-level measurements on stored packages

In the context of the naturally occurring radioactive material associated with petrol exploitation, it is important to determine the concentrations of 226Ra and 228Ra in contaminated sludge originated from this activity and stored in packages. Although measurements based on chemical analyses of samples from package content can be done, difficulties associated with the collection and analyses of samples may be avoided by employing theoretical models based on the emitting radiation levels from the mentioned packages. This article presents a methodology to estimate 226Ra and 228Ra concentrations in sludge stored in cylindrical drums, employing a model developed in the Mathematica software. The model takes into consideration the radiation levels measured at one meter from the top surface of the waste package containing the contaminated sludge. It also takes into consideration packaging dimensions, waste density, time of measurement, among other factors, and allows the determination of all radionuclides concentrations in the sludge, helping to minimize the costs associated with sampling and analyses. Moreover, this proposed model is an alternative solution to pre-existing methods and can also assist operators, regulators, and decision-makers in the prediction of short- and long-term radiological impacts on human beings and on the environment, due to the disposal of waste containing naturally occurring radioactive materials.