L-099 Updated Review of Ignitions Mechanisms and Small-Scale Tests Related to CookOff

This report was originally published in December 2003 and some areas, testing in particular, have been updated in support of MSIAC‟s 2016 Atlanta Science of Cookoff workshop. A review of current knowledge in cookoff phenomena is proposed. Some key factors influencing pre-ignition, ignition and post-ignition phenomena, such as: confinement, heating rate and damage are discussed. This report reviews also the small-scale experimental capabilities being used to study these key factors and phenomena. A compendium of tests results and data related to over 20 small-scale tests, as well as bibliography sorted by nations and organisations is included.

Cookoff is a serious and costly hazard that has an impact over a broad range of disciplines, impacting munitions design, testing, transportation, and storage, as well as fire fighting response. Historically, the US Navy initiated Insensitive Munitions efforts after several fire related, high consequence, accidents on aircraft carrier decks during the Vietnam War (USS Oriskany in 1966, USS Forrestal in 1967 and USS Enterprise in 1969) and during the Libya Operation (USS Nimitz in 1981). The risk posed by fire involving munitions is one which is relevant to all nations and services and is ever present throughout the munition lifecycle; whether it is the primary or secondary threat stimulus (fire often results from munitions being subjected to external unplanned stimuli). The recent accident in Cyprus in 2011 is a reminder of the catastrophic consequences that can occur. In this incident, ignition of propellant due to stabiliser loss eventually resulted in 500,000kg of HD 1.3 material undergoing a mass detonation which tragically led to the loss of 13 lives and caused three billion Euros of damage1 . As a result, much effort has been directed towards understanding the behaviour of munitions subjected to cookoff. One of the last cooperative efforts is the “US Great Cookoff Challenge” initiated in 1995 in order to unite experimental and modelling efforts. Some other nations have also undertaken similar efforts. During the 12th International Detonation Symposium, August 11 - 16, 2002, Wyndham, San Diego, cookoff experts held a short meeting to discuss deficiencies in understanding and predicting cookoff. As follow-on to this meeting, MSIAC (then NIMIC) offered to prepare a cookoff report. In order to increase the relevance, completeness and accuracy of this document, it was also proposed to create an international Cookoff Hazards Working Group (CHWG, see Annex 4) that would, using the Internet as a communication means, periodically review and comment on the different sections of this document. The first version of this report, published in December 2003, summarises what was achieved by this e-group. In preparation for the 2016 MSIAC Science of Cookoff workshop parts of this report were updated by French ENSTA trainee Grégoire Jacquemin under the supervision of Dr Matt Andrews. This effort focussed on updating the Annex 2, „Compendium of Small-Scale Tests Dedicated to Cookoff‟. Significant additional data was added as well as descriptions of some additional tests. Updates have also been added to the introductory sections of this report. However, the workshop discussion should provide valuable additional input which could be added following the meeting.