2018 International Explosives Safety Symposium and Exhibition
PHYSICAL EFFECTS AND CONSEQUENCES FROM DETONATIONS AND LESS
VIOLENT MUNITION RESPONSES – AN OVERVIEW
Martijn van der Voort, Ernie Baker, Christelle Collet
Munitions Safety Information Analysis Center (NATO), Brussels, Belgium
Abstract
An increasing number of warhead designs shows a less violent response than Detonation (type I) in cook off or
impact scenarios. In order to quantify the safety benefits, MSIAC is working on improvements in the risk
management of such munitions. For Deflagration (type IV) and Explosion (type III) reactions, only limited
quantitative information exists about the physical effects and consequences. This includes primary fragmentation,
internal pressure loads and projection of debris from storage structures, as well as external blast (or pressure) waves
and thermal effects. In storage conditions, the larger scale and confinement introduces additional complexities. This
paper discusses relevant data and presents a first step towards the development of models.
Due to the reduced reaction rate, fragmentation typically leads to larger strip-like fragments, but with a smaller
velocity. Trajectory calculations have been carried out to illustrate the influence on impact distances. Tests have
shown that impact distances can even increase due to a smaller deceleration by airdrag. The occurrence of a small
number of fragments with a large impact distance raises questions about appropriate definitions for safety distances.
Compared to detonations, break-up of storage structures will occur at higher loading density (NEQ per volume) for
less violent munition responses. Detailed knowledge about the storage construction and in particular vent areas, is
essential to determine the overall response. As for primary fragments, structural debris will increase in size and
reduce in velocity, however the debris throw may also become more directional. A number of adaptions to the
Debris Launch Velocity (DLV) equation are discussed to account for sub-detonative behavior. These are a reduction
in either the available energy for acceleration or a reduction of the effective acceleration path length. External blast
will reduce in strength, which can be represented with reduced TNT equivalencies, but more appropriate are models
that account for a lower reaction rate and lower explosion overpressures. The potential of the Multi-Energy method
(originally developed for gas-explosions) has been investigated.
We recommend that standardized IM tests are extended with a more detailed measurement of fragmentation and
blast for the purpose of model validation. The IM test standards could also specify more quantitative measures to
help define the munition response in terms of reaction rate. It is also recommended that the international community
focus on full scale testing of IM. CFD and engineering models could focus more on internal pressure development
and structural response for limited reactions rate. We hope that the findings in this paper will aid the development of
Quantity Distances (QD) and risk management of future munitions for a range of responses.
Introduction
An increasing number of warhead designs shows a less violent response than detonation in cook off or impact
scenarios. In order to quantify the safety benefits, MSIAC is working on improvements in the risk management of
such munitions.
The Insensitive Munitions European Manufacturers Group (IMEMG) has produced an overview of national and
international Insensitive Munitions (IM) requirements (Figure 1). This overview shows that for most standardized
threats as given in [AOP-39, 2010] the criterion is to have a response equal to or less than a Burn (type V),
Deflagration (IV), or Explosion (III).
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