Insensitive Munitions for the Tactical Level
Introduction
While working on staff, most questions that come up related to ammunition are not that difficult and are usually repetitive regardless of assignment. To keep operational security, the abbreviated version of the request for information from our multinational partner was; What is Insensitive Munitions, and How does it relate to current operations? To my surprise, I went into a mixture of self-taught history lessons and current trends in munitions technology. Then ultimately, the writing of this article to share with the ammunition community.
Background
To understand the subject, we must define insensitive munitions (IM), which are munitions that are less vulnerable to accidental and combat propagation than the same type of munitions but still retain their performance capabilities for combat or training purposes. From this point on, the topic gets increasingly complicated and very much falls into the hazard classification and testing of munitions. With the United States (US) Federal Explosives Regulations, the United Nations (UN) International Ammunition Technical Guidelines (IATG), and the North Atlantic Treaty Organization (NATO) standardization agreements (STANAG) the cohesive standards for the introduction and classification of new munitions or explosives can be very complicated. The complication becomes increasingly apparent when the hazard classification tests and determination of a munitions’ IM characteristics do not align with each other. As such, NATO has created an Insensitive Munitions (IM) / Hazard Classification (HC) Harmonization Custodial Working Group in their AC/326 Ammunition Safety Group. To define the required policy hierarchy to enable IM/HC harmonization, which has been inactive over the past few years and to deal with today’s problems.
History
The history of insensitive munitions is explained thoroughly by Raymond L Beauregard at insensitivemunitions.org. He offers a first-hand account of Insensitive Munitions and how we got to IM today.
http://www.insensitivemunitions.org/
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I offer a synopsis that, with the advent of black powder, what was needed was the ability to handle explosives material safely. So the creation of better explosive material was introduced, such as unfamiliar dunnite (ammonium picrate), also known as Explosive D. In time, the more familiar TNT, RDX, Composition B, and Composition C-4 offered a safer alternative. It allowed for better handling of insensitive substances. While these composites offered a better alternative, the increase in technology and science has created the ability for explosives to be even more insensitive for greater safety in transportation, storage, and handling.
Current Munitions
The U.S. Army has replaced explosive TNT in artillery munitions. The replacement, now in production, is called Insensitive Munitions Explosives, IMX-101 produced by BAE Systems Inc. at Holston Army Ammunition Plant in Tennessee. The composition is an insensitive high explosive, which makes the munitions safer to handle and store, such as the M795 and M1122 Artillery rounds. Other compositions include IMX-104 as a Comp-B replacement for M888, M889A2, and M934A1 Mortar rounds. The United States is not the only nation moving towards insensitive munitions explosives. Another includes FOX-7 from Swedish National Defence Research Institute. The replacement of TNT and Comp-B with IMX-101 and IMX-104 is not a simple task that just gets accomplished with changing the explosives. Before using the new compound, required is a full range of extensive testing following MIL-STD-2105 and NATO STANAG. The available full list of tests is at the National Technical Systems website.
https://www.nts.com/services/testing/defense/insensitive-munitions/
Tactical Level
Now that I have answered the question of what insensitive munitions are, with the technical data. More importantly, how does it relate to current operations to the user in the field? The short answer, it does not change the current practice, but we may see changes in the future. For now, we must look into the past. Hazard Class 1 are Explosive Materials, has the most common divisions of 1.1 through 1.4, which describes the potential hazard posed by the explosive and are:
Division 1.1 Explosives (with a mass explosion hazard)
Division 1.2 Explosives (with a projection hazard)
Division 1.3 Explosives (with predominately a fire hazard)
Division 1.4 Explosives (with no significant blast hazard)
Now two that are not so familiar, but established since 1988, are 1.5, Very insensitive explosives, blasting agents, and 1.6, Extremely insensitive detonating substances.
Figure 1. Hazard Class 1 and Divisions.
The 1.5 is for blasting agents, which may be any material or mixture, consisting of a fuel and oxidizer, intended for blasting, not otherwise classified as an explosive. An example is inorganic nitrates (ammonium and sodium nitrates) and carbonaceous fuels. Adding an explosive ingredient turns a composition from a blasting agent into an explosive. For 1.6, Extremely insensitive detonating substances; the Defense Explosives Safety Board (DDESB) in Defense Explosives Safety Regulation 6055.09 Jan 13, 2019:
Hazard Class 1.6; as Ammunition Explosives (AE) that exhibits no reaction more severe than burning in the liquid fuel or external fire, bullet impact, and slow heating tests.
Along with these hazard divisions is storage Compatibility Groups (CG) that are assigned to ammunition based on the similarity of function, features, and accident effects potential. Compatibility Group N, ammunition/explosives contain only extremely insensitive detonating substances (EIDS). Currently, the 1.5 hazard division is mostly reserved for articles that are not explosives but make up the final explosives material. There are no US munitions that are classified as 1.6, even if the munitions pass UN and NATO IM testing.
Conclusion
While Insensitive Munitions makes military operations safer, the multiple levels of national and international regulations will have to catch up to technology. The creation of Insensitive Munitions / Hazard Classification Harmonization Custodial Working Group is the right direction to understanding where munitions that pass UN and NATO IM testing fits into the hazard classification. The updates may require updating definitions of Hazard Definitions and a combination of reviewing testing criteria for classification with updated UN and NATO regulations. As tactical level users, we must understand Insensitive Munitions Technology and how it relates to the multi-national and Joint Logistical Environment. We must also look beyond the 1.1 through 1.4 hazard divisions and prepare for how technology will develop munitions. Including how we in field Ammunition Supply Points will take advantage of the technology to win in large scale combat operations.