Ensuring diver safety during munitions recovery
A new research project has been launched to develop safety systems for divers tasked with salvaging wartime munitions that have been dumped at sea. Sensors alert the divers to acute levels of TNT and other hazardous substances, and an alarm system shows them the source of danger in real time by means of an augmented reality display inside their goggles.
Kiel: Vast quantities of munitions from the two world wars lie at the bottom of the North and Baltic Seas off the coast of Germany. Current estimates put the amount of chemical warfare agents at around 220,000 tonnes. Recovering them from the seabed is not only complex and therefore expensive, but also dangerous. The shells, which are mainly made of metal, have gradually been corroded by salt water over the decades. As a result, hazardous substances have increasingly seeped into the surrounding waters and polluted the seabed. This poses a danger not only to the environment, but especially to the professional divers, who – despite technological progress and the increased use of underwater vehicles – are still at the sharp end of any salvage operation.
Innovative sensor technology for enhanced safety under water
Against this background, a consortium of companies and research institutes in northern German has set up the TOxAR project. The aim is to develop an all-round occupational safety system for underwater operations. It is based on a series of new sensors that detect and measure both the waterborne components of conventional warfare agents – primarily TNT – and chemical substances such as mustard gas or arsenic degradation products. The latter can cause skin burns on contact and are suspected of being carcinogenic. The danger for divers and diving crews who handle the source of these substances directly or with contaminated diving equipment is extremely high.
Detecting and communicating in real time
In the future, divers on a mission to salvage discarded munitions may be able to scan the search area with sensor lances beforehand. This is the technical basis for the crucial element of the safety system, namely real-time communication. The instant transfer of measurement readings is a much greater challenge under water than on land. The lances therefore fulfill the dual role of carrying sensors for warfare agents with an arsenic content and chemical contamination of the sediment as well as being navigation/communication nodes. The precise position of the diver under water is determined, an escaping plume of contaminants is analyzed and a potential hazard is immediately identified. Cable-free, digital acoustic communication has to be established not only between lance and diver, but also with the ship and/or land-based monitoring and control team. It is essential that this communication is reliable at all times for purposes of risk assessment and navigating in poor visibility.
Diving goggles with AR
The swirling of sediment during the examination of objects causes the water to take on a cocoa-like consistency, which always presents a challenge for divers. When recovering warfare agents, a sudden reduction of visibility to a few centimeters quickly constitutes a threat. This is why Fraunhofer IGD is developing an augmented reality system for diving goggles as part of the TOxAR project. Divers can see the contaminant level in the water and sediment as measured by the sensor system together with its exact location on a display inside their goggles or on a wrist-mounted device. This makes it possible to withdraw to a safe distance much more speedily than before in the event of danger from pollutants, and precautions to contain the danger can be initiated immediately. In addition, other relevant information for the dive, such as compass headings, undersea charts or position, can be communicated to the diver. During the development of the display, special care was taken not to distract the diver or unnecessarily restrict the field of vision.
The project team, led by MacArtney Germany GmbH based in Kiel, will advance development to the point where a demonstrator can be put through its paces. Fraunhofer IGD at Kiel is working in collaboration with various partners, including the Hamburg University of Applied Sciences, EvoLogics GmbH from Berlin, Miprolab Mikrobiologische Diagnostik GmbH and the Institute for Nanophotonics IFNANO e.V. from Göttingen. They are receiving additional support from Baltic Taucherei- und Bergungsbetrieb Rostock GmbH, HCG Hazard Control GmbH and Nationales Informationszentrum Chemische Kampfmittel e.V.
The TOxAR project is set to continue for the next 2½ years and is funded by the German Federal Ministry for Economic Affairs and Energy (BMWi).