LZH develops underwater laser method for defusing explosive ordnance in the sea

Together with project partners, the LZH is developing a process to defuse world war ammunition under water using a laser. The goal: to affect the ecosystem as little as possible while saving time and costs.

In the North and Baltic Sea, approximately 1.6 million tons of war ammunition lie on the seabed. The danger of unforeseen detonations is not the only problem. Over time, the water causes the steel shell of the explosive ordnance to corrode, releasing the explosives into the sea - with significant consequences for humans, animals and the entire ecosystem. Removing explosive ordnance, however, is a challenge: blasting underwater is not only dangerous, it also creates significant pressure waves and affects the sea dwellers that live there. Also, unreacted, environmentally harmful explosives can spread in the sea after detonation. In the project UNLOWDET, scientists of the LZH are working on a solution together with the companies LASER on demand GmbH and EGGERS Kampfmittelbergung GmbH: They are researching how to defuse explosive ordnance underwater remotely controlled by a laser. Thereby, the impact of the blasting on the environment shall be reduced.

Laser-induced detonation for more efficient defusing
The LZH has already developed a new method for defusing unexploded ordnance on land based on laser technology in the project DEFLAG. (Photo: LZH)
For this, the project partners are following the approach of a "Low-Order Detonation", in which, in contrast to the "High-Order Detonation", only a small part of the explosive is reacted. In the  first step, a laser beam is used to make a defined joint in the explosive ordnance, thus weakening the shell. In the second step, a Low-Order Detonation is then to be triggered with the laser beam, so that the detonator is removed and the ignition chain is interrupted. Since the system technology is to be positioned at the explosive ordnance with a diving robot, the process can be controlled from a distance.

This method makes the process of defusing not only safer but also significantly more efficient: For example, the time-consuming and cost-intensive application of bubble curtains, which are usually used for noise protection during blasting, can be dispensed with. At the same time, the risk of unreacted explosives spreading in the sea after detonation is minimized.

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