DOI: 10.5061/dryad.sqv9s4n91
title: Increased impact sensitivity in ageing high explosives: Analysis of Amatol extracted from explosive remnants of war

description: Millions of tonnes of explosive remnants of war remain in nature, and the
 volume is continuously growing. The explosive legacy of wars represents an
 increasing threat to the environment and to societal safety and security.
 As munitions continue to deteriorate, harmful constituents will eventually
 leak into the environment, poisoning ecological receptors and
 contaminating the surrounding soil and groundwater. Deteriorating
 munitions may also become increasingly sensitive to external stimuli and
 may be susceptible to accidental detonation. To thoroughly assess how to
 address these ageing munitions, we must first establish certain threshold
 values for the safe and secure handling and final disposal of the
 explosive ordnance. One key factor is to establish how the impact
 sensitivity of the explosives evolves over time. In the present work, we
 investigated the high explosive substance Amatol extracted from ageing
 explosive remnants of war. The results obtained in the analysis indicate
 that the high explosives in the examined specimens generally were much
 more sensitive to impact than previously assumed. Furthermore, the
 analysis revealed that the standardised methodology of impact sensitivity
 testing was insufficient for estimating the sensitivities in question, and
 a more careful statistical analysis was required.
description: In this analysis the OZM BHF 12 BAM impact apparatus was applied.
 The tests were performed in accordance with the requirements of the test
 procedure decribed in NATO STANAG 4489, Annex C; BAM impact
 machine.
description: # Increased impact sensitivity in ageing high explosives; analysis of
 Amatol extracted from explosive remnants of war Data from impact
 sensitivity tests using the BAM Impact Apparatus, demonstrating that
 Amatols extracted from ERW, with the expected exception of the sample of
 high moisture content, are still sensitive to impact. For only one of the
 samples studied, the impact sensitivity coincided with what is recorded in
 the literature as expected values for Amatol. All the other samples
 studied were on the other hand significantly more sensitive to impact. In
 the most extreme case, namely substance B, the substance was more nearly
 than four times more sensitive than expected for Amatol (the estimate
 value of  being only 7.52 J, which is nearly less than a quarter of the
 expected value of 30 J). Note also that for this substance, we observed
 reactions with impacts as low as 6.18 J. The study therefore shows that
 the impact sensitivity of Amatol high explosives extracted from ageing ERW
 are suasible of becoming increasingly sensitive to impact. ## Description
 of the data and file structure The impact sensitivity of an explosive
 substance is its susceptibility to detonation under impact. This parameter
 characterises the safety of explosives in handling and transportation. To
 determine the impact sensitivity of a substance, a type of device known as
 a fallhammer apparatus is normally applied. There are several versions of
 these types of devices, but the United Nations recommends the
 Bundesanstalt für Materialforschung und -prüfung (BAM) fallhammer, which
 has also become the most frequently used standard impact sensitivity
 measuring device, however, the various apparatuses all operate on the same
 principle: A  sample of assorted sizes of the tested explosive substance
 are subjected to the impact of falling weights, and the researcher
 estimates the sensitivity of the explosive based on which heights resulted
 in explosions. Depending on the characteristics of the tested explosive
 substance, the mass of the drop weight and the drop height (the combined
 product of which is the impact energy), the sample may or may not initiate
 upon impact. In judging the results, a distinction is made between *no
 reaction*, *decomposition* (without flame or explosion) and *explosion*
 (with weak to strong report or inflammation). When assessing sensitivity,
 our primary interest is in quantiles such as h<sub>50</sub>,
 which is the height from which there is a 50% probability of a reaction
 occurring. We used the existence of a bounded 95% confidence interval (CI)
 for h<sub>50</sub> as a necessary criterion for terminating
 our fallhammer experiments. As repeated drops from the same height in a
 fallhammer will not invariably yield the same result (reaction versus no
 reaction), the impact sensitivity of an energetic material must be
 estimated statistically. Hence, the weight is dropped repeatedly from a
 range of (log) heights, and for each drop, we observe a binary outcome,
 recorded as a "1" if a reaction occurred and
 "0" otherwise. The dataset contains the full data from the
 impact sensitivity tests using the BAM Impact Apparatus. The main results
 are as follows: * For substance A<sub>1</sub>, we initially
 aimed to obtain a single reaction with a 5 kg weight, but when this was
 not achieved, we proceeded to drop a 10 kg weight to increase the impact
 energy. After the first five drops, we still had no reactions, and we
 therefore decided to execute 10 drops from the maximum height of 100 cm
 with the 10 kg weight. Out of these, only a single drop caused a reaction.
 * For substance A<sub>2</sub>, we did not obtain a bounded
 95% CI for h<sub>50</sub> after the first 30 drops, and we
 therefore increased the number of drops in increments by 10 at a time
 until a valid confidence interval was achieved. This happened after
 70 drops. * For substance B, we decided to stop the experiment after
 30 drops, since this proved to be sufficient for obtaining a bounded 95%
 CI for h<sub>50</sub>. * For substance C, as with substance
 A<sub>2</sub>, we had not achieved a bounded 95% CI for
 h<sub>50</sub> after the first 30 drops, and therefore decided
 to augment the dataset by increments of 10 drops until this was achieved.
 After 50 drops, we had a 95% CI for h<sub>50</sub>. * For
 substance D, since we had not obtained a bounded CI for
 h<sub>50</sub> after 30 drops, we increased the number of
 drops by increments of 10 until this was achieved. This happened after
 70 drops. * For substance E, since 30 drops were not sufficient for
 obtaining a bounded 95% CI for h<sub>50</sub>, we increased
 the number of drops by increments of 10 until a valid CI was obtained,
 after 70 drops. <br>