O-034 Summary of 1997 NIMIC Workshop on Testing of Fast Heating, Slow Heating and Sympathetic Reactions: US Perspectives

A workshop on insensitive munitions (IM) test methodology was sponsored by the NATO Insensitive Munitions Information Center (NIMIC) on 20-23 May 1997 at NATO Headquarters in Brussels, Belgium. Approximately 75 experts from nine countries attended the meeting, covering disciplines such as systems safety, hazards testing and instrumentation, energetic materials characterization, and explosives safety. The meeting covered four full days and included a one and one-half day plenary session, two days of working group discussions, and a final half day concluding session.

The purpose of the workshop was "to write guidance on full scale IM testing in order to improve confidence in, and achieve international acceptability and broader applicability of, test results." A significant part of the meeting consisted of working group sessions covering issues such as: development of a logic protocol for IM testing, including influence of a threat/hazards analysis on test parameters; usefulness of small scale experimental explosiveness data and modeling to improve confidence in full scale test results; standardization of input (stimulus) and output (response) parameters and measurements to be employed in full scale tests; definition of appropriate quantitative hazard response descriptors and hazard levels useful for distinguishing the IM characteristics of a munition with respect to the surrounding environment; and evaluation of overlapping test requirements between IM and final hazard classification protocols, including the best features of each set of tests.

As an overall test policy, the argument was made that the purpose of IM testing should be to characterize the susceptibility of a munition for possible reaction mechanisms incurred from a given threat stimulus. Thus, fundamental mechanism testing, possibly modified to incorporate results of the threat/hazards analysis, may be appropriate. Realistic application of the IM test results then requires interpretation based on a systems (platform) hazard analysis and must also include results of small scale testing - that is generic testing, material characterization and modeling. This approach was deemed essential to an IM assessment, and coupled with design analysis may make full scale testing not required in some situations. As a result no IM assessment should be based solely on the results of full scale munition tests.

New ideas for characterizing the response of a munition in an IM test were also advanced. The new concept involves a set of quantitative response descriptors characterizing airblast, fragments, thermal flux, time-to-response (or no response), propulsiveness, toxic cloud dispersion, and secondary effects (such as terminal effects of firebrands). A yard stick for establishing thresholds for these descriptors should be based on the effects on personnel, evaluated against a set of defined hazard arcs. Values for these thresholds were proposed, and definitions for Type VI and VII responses were also suggested where the current type V criteria may not be stringent enough.

The meeting was the first in a two-part workshop. This first part focused on fast and slow cookoff (FH and SH) and sympathetic reaction (SR) testing. The second part will focus on bullet, fragment, and shaped charge jet impact testing and will be held the week of 17-21 November 1997 in Australia. This paper will summarize the findings from the first part held in Brussels. Proceedings of the first workshop are contained in Volumes I and II of the NIMIC IM Testing Report