Disaster Risk Reduction (DRR) within a society and Business Continuity Management (BCM) within a company are only possible if its known how to act in extraordinary situations. Today where everything is possible, where a lorry can have used as a deadly weapon it is time to understand more about dirty bombs with Cs-137 ions and how fast they migrate under different conditions into the built environment. To know more about migration of 137Cs-Ions would enable us to know how fast we have to react after an nuclear incident or terror attack. To react a society needs to know more about reliable tools like detergents or methods to decontaminate the surfaces. This research will test the common available NATO approved detergents as close as possible to real scenarios and the test setting will give information’s about real migration velocity into concrete, roof tiles and two classical sandstones under different weather conditions and orientations. Working with Cesium137 is not easy and would be highly restricted due to its long half-life of 30 years and its strong radiation. Therefore, the work was carried out with the common Cs-134 with the identical chemical properties but without the danger of radiation. Two methods of contamination were tested and compared: blasting up a real dirty bomb producing a fine aerosol and controlled application of a solution by drops on the surface. Measurements showed that the Cesium ions remains more than expected on the surface and that beside commercial OCTAN approuved products tap water worked as well.