Schleswig-Holstein.NABU.de Natur vor Ort Meeressäuger Symposium Ammunition Removal

Underwater Explosion - An incomplete Combustion Process

Underwater Explosion - An incomplete Combustion Process - Which critical Substances end up in the Sea?

Summary of the lecture and presentation by Fritz Pfeiffer, Büro für Umweltgeologie und Sicherheitsforschung (Office for Environmental Geology & Security Research), Marburg, at the symposium “New methods of ammunition removal in the North and Baltic Sea“ held in Kiel on 19 October 2007

Explosives can be converted in different ways:

• exothermic destruction through detonation or deflagration.
• endothermic destruction through catalyzed conversion reactions

The quantity and composition of the reaction products is mainly determined by the way of conversion. High order detonations result in conversions with very high energy density, the shock wave, however, is also extremely strong. Charge transformation is almost complete.

Low order detonations or deflagrations do not cause strong shock waves, but because the charge is dispersed, large amounts of critical substances such as explosives or reaction products from incomplete combustion are released.

Especially in the case of old explosives, detonation does not guarantee complete conversion. For submersed aged explosives in particular, complete detonation (high order) can not be taken for granted.

Follow-up monitoring is necessary, i.e. targeted search and appropriate analyses (system equilibria as well as water, sediment and organism samples). When destructing (decomposing) the explosives, the site and possible exposure paths (enrichment in the sediment or via the food chain) need to be monitored.

Unfused torpedo heads do not have to be exploded or recovered via the water surface (i. e. exposed to air). Deactivation and destruction are possible under water (e.g. feeding into a detonation chamber via wet well or photolytic ammunition removal).

Shooting wool “Schießwolle” 39/39a has nothing to do with gun cotton: it is a highly explosive (HE-)composition and does not contain any nitrocellulose stabilizers. Moreover, its sensitivity does not increase significantly when getting in contact with sodium chloride solutions such as sea water (subject to data from on-site samples). The naval explosives discussed in this presentation do not have anything in common with the research presented by Bohn (2007) which refers to gun cotton & TNT-NaCl mixtures.

Bibliography
Bohn, M. A. (2007): Wenn Explosivstoff älter wird, wird er auch gefährlicher? (Do explosives become more dangerous with age?) - Ammunition removal and the time aspect. Analyses of changes in sensitivity. Symposium “ammunition removal” held by the association of German explosive ordnance specialists in Bad Kissingen from 12 to 13 February 2007.

Contact
Fritz Pfeiffer, geologist
Büro für Umweltgeologie und Sicherheitsforschung
Office for Environmental Geology & Security Research
Am Glaskopf 8
35039 Marburg
Tel. +49-6421-309432
projectfritz@web.de

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Presentation “Underwater Explosion - An incomplete Combustion Process” (pdf; 0,5 MB)

 

 

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