Logo: to the web site of the Swedish Defence University

The clearance of unexploded ordnance (UXO) and other explosive remnants of war (ERW) containing shaped charge warheads poses a particular technical hazard to consider for EOD personnel. The wide use of light anti-tank weapons, such as rocket propelled grenades and the scattering of sub-munitions in different conflict areas have made the clearance of shaped charge ammunition a frequent task. However, unlike other hazards, for shaped charges, EOD personnel lack adequate means for the establishment of the maximum danger area and for the design of measures for hazard confinement against the shaped charge effect. This shortcoming limits the responsible EOD officer to rough estimates and guesswork without scientific support, in these safety-related decisions.

This paper is based on a SNDC military technology thesis, (1). In the thesis two different models, which together give guidance for protective measures during clearance of shaped charge ammunition, are suggested. The development of these models is based on their military utility, by consideration of the limited information availability, the short time frames, the working methods and the technology level that are characteristic for EOD operations.

The first model is intended for use in the design of measures for hazard confinement against jet penetration. The suggested model is derived from a combination of two existing models for the shaped charge effect. A model for shaped charge penetration in single layered media developed by the Swedish Defence Research Agency (FOI) is used as the basis for the model. This is then combined with a modified model that describes how the penetration depth decreases with an increasing stand-off distance. Together they give a simple model for calculating the minimum thickness of barricades and mounds to withstand the penetration of shaped charges at varying distances.

The second model is for estimation of the maximum hazardous area generated by the shaped charge jet. This calculation model is based on the trajectory of the most critical jet segment, i.e. the slug. By defining typical values for those parameters that EOD personnel normally do not have information about, this model can be described with a simple graph. The graph gives the maximum hazardous area based only on the calibre and the elevation of the ordnance. The slug may be stable or unstable in its trajectory - the former giving a significantly larger hazardous area. As the conditions for or the probability of which will apply in a particular case is, currently, not supported by adequate scientific data, figures are given both for a stable and a tumbling slug segment. The use of the figures for an unstable slug will lead to a smaller area at the expense of higher risk.

The two suggested models are developed further into a set of "tools" for the design of protective measures. These tools are adapted to the unique nature of EOD operations, and consist of a complete set of design rules giving a versatile tool to replace today´s rough estimates and guesswork.