L-097 Assessing Thermal Threats

December 2003
Frédéric Peugeot (Detonics and Ballistics)

Thermal threats to munitions lurk everywhere and a wide range of heating rates is expected in the actual threat environment. Wherever combustible materials and munitions are proximate, there is potential for fire and consequent heating of munitions, either directly or indirectly. Inflammable liquids, wood, steam, solar radiation and energetic materials are examples of potential heat sources.When assessing an ordnance life cycle, several cookoff scenarios can therefore be identified. The objective of this section is to identify, qualify and quantify credible thermal threats from malicious attack or accidents that may occur during the life cycle of a munition.

The information presented is a compilation of excerpts from studies done by A. Victor who conducted the THAs for THAAD, Patriot PAC-3, Advanced Rocket System (ARS), Advanced Bomb Family (ABF) and JSOW [4,5], studies done by participants to the 1993 NIMIC cookoff workshop [3,10,11] and other relevant sources dealing for example with shipboard fire [2,7,8,9] or the fire community. Classified data, such as the extreme temperature rates identified by Fontenot and Jacobson [1] or PAC-3 data [6], have not been included. It should nevertheless be mentioned that their work forms the basis for the heating rates used by Victor.

It should be noted firstly that because there is a requirement for both standardized heating rate tests1, and tailored tests2, it is not our intention here to question the credibility of the current slow and fast heating rates. Therefore, this section should be looked at as a resource document for determining appropriate heating rates applicable for a munition when performing a Threat and Hazards Assessment (THA) and more specifically a Thermal Threat Analysis.

It should be noted secondly that when defining a thermal threat, the heat source characteristics as delivered by the source or as seen by the energetic material inside the ammunition should not be confused. This section is therefore split into two parts. The first one, chapters 1.1 to 1.4, is dealing with the actual heat source characteristics, i.e. from the point of view of the threat. The second one, chapter 1.5, is dealing with the energetic material, i.e. from the point of view of the threatened.