Unexploded ordnance (UXO) is explosive ordnance that was fired, dropped, launched or emplaced and failed to function as intended, and therefore remains liable to explode. Artillery and mortar shells, aircraft bombs, rockets, grenades, submunitions, mines and chemical munitions persist in soils, river beds and seabeds long after a conflict ends. DEMINETEC assesses, detects and clears UXO before and during construction, infrastructure and energy projects in France and abroad; its subsidiary SEMTEC covers underwater sites.
UXO, AXO, ERW, MNE, REG: definitions
| Term | Meaning | Scope |
|---|---|---|
| UXO | Unexploded ordnance | Ordnance primed, fuzed, armed or prepared for use, fired, dropped, launched or projected, which failed to explode. |
| AXO | Abandoned explosive ordnance | Unused ordnance left behind or dumped by a party to a conflict and no longer under its control: abandoned depots, buried caches, munitions dumped at sea. |
| ERW | Explosive remnants of war | UXO + AXO, as defined by Protocol V (2003) to the Convention on Certain Conventional Weapons. Mines are excluded from this definition. |
| MNE | Munition non explosée | French equivalent of UXO. |
| REG | Restes explosifs de guerre | French equivalent of ERW. |
| EO | Explosive ordnance | Generic mine action term covering mines, cluster munitions, UXO, AXO, booby traps and other explosive devices. |
On site these distinctions do not change the level of precaution: a fired shell, an abandoned bomb and a mine are all handled by qualified EOD personnel. They matter in international contracts, in reporting to national mine action authorities and in information management systems such as IMSMA, where each item is recorded in its category. DEMINETEC reports in English and French using both terminologies.
Where UXO comes from
In Western Europe, contamination mainly derives from the 1870-1871 war, the First World War front lines (northern and eastern France, Belgium), Second World War bombing of ports, railways and industrial sites, the 1944 landings and the retreat battles, as well as former military training areas, ammunition depots and post-war disposal sites. Elsewhere, more recent conflicts leave mixed contamination of mines, cluster munition remnants, artillery and mortar UXO and abandoned stockpiles. Even a small proportion of fired ammunition failing to function leaves large quantities of UXO on former battlefields.
Main families of ordnance encountered
Artillery and mortar projectiles
High-explosive, shrapnel, smoke, illuminating, incendiary and chemical shells, fitted with impact, time or proximity fuzes. Fuze condition determines whether an item may be moved.
Aircraft bombs
General-purpose and armour-piercing bombs from a few kilograms to over a tonne. In soft ground, WWII bombs can penetrate several metres, which requires borehole magnetometry ahead of piling or deep foundations.
Mines, grenades, rockets and submunitions
Anti-personnel and anti-tank mines, hand and rifle grenades, rockets and submunitions with high failure rates. See mine clearance and demining.
Chemical munitions
Munitions filled with sulphur mustard, phosgene or arsenical agents. Their discovery stops operations and triggers a specific procedure with the competent State services.
Underwater ordnance
Sea mines, torpedoes, depth charges, bombs dropped on harbours and bridges, and munitions dumped at sea after the World Wars. These are handled by SEMTEC underwater UXO clearance.
Why old ordnance remains dangerous
Explosive fillings such as TNT, amatol or picric acid remain energetic. Picric acid in contact with metals forms picrates that are highly sensitive to shock and friction. Corrosion can expose the filling or jam a fuze in an unstable position, and clockwork or chemical delay fuzes can be disturbed by vibration. For these reasons UXO is never moved without assessment by a qualified EOD operator, and construction machinery must stop as soon as a suspect item appears.
From risk assessment to clearance certificate
- Desk study / historical UXO risk assessment: archives, aerial photographs, records of previous finds; output is a zoning of the hazard by area and depth. See pyrotechnic risk management.
- UXO survey: magnetometer and electromagnetic surveys, borehole magnetometry for deep targets, anomaly picking and target listing. See UXO survey and detection.
- Intrusive investigation and clearance: excavation of targets, identification, render-safe or removal, destruction in compliance with safety distances. See UXO clearance and EOD.
- Construction support: EOD watching brief during earthworks, dredging and drilling. See pyrotechnic safety for construction.
- Deliverables: as-built anomaly maps, clearance report and certificate stating areas and depths cleared.
Standards and regulatory frameworks
In France, UXO clearance linked to construction works is governed by decree 2005-1325 as amended: the pyrotechnic safety study (ESP), prepared under the clearance contractor's responsibility, is submitted by the project owner to the DREETS, which obtains the opinion of the explosives inspectorate. Pyrotechnic activities in industry fall under articles R.4462-1 et seq. of the French Labour Code (decree 2013-973). Internationally, work follows the International Mine Action Standards (IMAS) and their national derivatives, and the International Ammunition Technical Guidelines (IATG) for stockpiles. See pyrotechnic regulation.
Frequently asked questions about unexploded ordnance
What is unexploded ordnance (UXO)?
Unexploded ordnance is explosive ordnance that has been primed, fuzed, armed or otherwise prepared for use, and has been fired, dropped, launched or projected, but has failed to explode. It remains liable to function. The French term is munition non explosée (MNE).
What is the difference between UXO and ERW?
Under Protocol V (2003) to the Convention on Certain Conventional Weapons, explosive remnants of war (ERW) means unexploded ordnance (UXO) plus abandoned explosive ordnance (AXO). Mines are regulated by other instruments and are excluded from the ERW definition. The French terms are MNE for UXO and REG (restes explosifs de guerre) for ERW.
Can a WWI or WWII munition still explode?
Yes. Military explosives remain energetic for decades and ageing can increase sensitivity: corrosion of the casing and fuze, exudation of the filling and formation of shock-sensitive compounds. Age is never a safety criterion.
How do you know whether a site contains UXO?
By a desk study (historical UXO risk assessment) that reconstructs combat, bombing, military use and previous finds, followed by a geophysical UXO survey (magnetometry, electromagnetic induction, borehole magnetometry) and intrusive investigation of selected anomalies.
Who is responsible for UXO clearance before construction?
The project owner commissions the risk assessment and clearance from a specialised contractor. In France, clearance linked to construction works is governed by decree 2005-1325 as amended, with a pyrotechnic safety study submitted to the regional labour authority (DREETS). Abroad, work follows the national mine action authority's standards, generally derived from IMAS.
Does DEMINETEC work underwater?
Yes, through its subsidiary SEMTEC, which performs underwater UXO survey and clearance in harbours, rivers and offshore areas, as well as general commercial diving works.
See also the UXO and EOD glossary. To discuss a project, contact DEMINETEC.