Nuclear risksDetecting carriers of dirty bombs

Published 5 September 2017

The threat of terrorism in Europe has been on the rise in recent years, with experts and politicians particularly worried that terrorists might make use of dirty bombs. Researchers have developed a new system that will be able to detect possible carriers of radioactive substances, even in large crowds of people. This solution is one of the defensive measures being developed as part of the REHSTRAIN project, which is focused on security for TGV and ICE high-speed trains in France and Germany.

For a long time, experts have been warning of attacks using dirty bombs, where terrorists mix radioactive material into conventional explosives such that it is scattered by a subsequent explosion. This is a real danger; ISIS, for instance, claims to have access to radioactive material. Security agencies are aware of the threat: last June, a U.S. port terminal in Charleston was evacuated and closed for several hours following a warning that a dirty bomb was on board a ship moored there. Once the all-clear was given, security personnel stated that they were being deliberately overcautious and had reacted accordingly.

Fraunhofer notes that dirty bombs are not a form of nuclear weapon, since they do not rely on a nuclear chain reaction occurring after they have been set off. The radioisotopes needed to make dirty bombs, such as cesium-137, cobalt-60, americium-241 or iridium-192, are easier to get hold of than fissile material for nuclear weapons; they are used in many nuclear medicine departments at hospitals and in research centers, but also for materials testing in industry. “Five grams of cesium – scattered by a couple of kilograms of explosive – is enough to cause billions of dollars’ worth of damage, to say nothing of the psychosocial effects and the impact on health. People who want to build these bombs are risking death through exposure to radiation – but that is unlikely to deter terrorists,” says Prof. Wolfgang Koch, a mathematician and physicist who heads the sensor data and information fusion department at the Fraunhofer Institute for Communication, Information Processing and Ergonomics (FKIE), based in Wachtberg, Germany.

Fraunhofer FKIE has developed an assistance system capable of detecting radiological threats in a stream of people and warning security personnel; this is the institute’s contribution to the Franco-German REHSTRAIN (Resilienz des Deutsch-Französischen Eisenbahn-Hochgeschwindigkeitsverkehrs) project, which is researching the vulnerability of ICE and TGV high-speed trains. Fraunhofer FKIE is developing the system as a subcontractor to Hochschule Bonn-Rhein-Sieg.