The article discusses the motion planning strategies for radiation map building. The gradient-based Bayesian method is used to bias the search of particular areas of the map, in which there is a high radiation level. The other strategy is the sequential-based Bayesian method, in which the robot visits the area cell. It is cited that automated tools are needed for fast assessment of threats, with the geopolitical situation. It is mentioned that the methods are not only suited to nuclear forensics but also to the assessment of contamination due to a release of radioactive isotopes.