In a weapons and munitions plant, technicians remotely lit the “cord” of explosive shavings lying underneath the explosive block scheduled for destruction by burning. After a few moments, the combustion of a portion of the explosive produced a detonation.

The quantity of secondary explosives to be burned amounted to 48 kg (ten 1.4-kg blocks of hexolite + 33 kg of dust generated from machining hexolite + 940 g of hexocil shavings + 300 g of dust from machining aluminium tolite wax), i.e. nearly twice the mass authorised under the safety guideline for burning.

No human consequences were reported since both technicians were protected inside the control room at the time of burning. The burning platform was destroyed; moreover, chunks of the concrete slab were projected 4 m into the air, and 2 craters (measuring 20 cm x 30 cm x 3 cm deep) were observed at the site where the detonation occurred. The explosion also caused a polycarbonate glass sheet to be stripped from a door on a building located 100 m away as well as a light grating to fall in a building 450 m away.

Several hypotheses relative to the detonation transition were imagined:

– self-confinement of melted explosive that would have flowed into a crack in the concrete zone,

– self-confinement of hexolite dust that was not sufficiently spread over the burning platform,

– reaction of the tolite wax aluminium powder with humidity of the burning platform,

– detonation of explosive particles enclosed in the slag present on the platform.

The site operator reminded technicians of the importance of initiating ignition from the shelter in addition to strict compliance with guidelines and operating procedures: safety guidelines were to be reviewed at least once a year. The operator issued this information to the entire staff as well as the Corporate Committee for Hygiene, Safety and Working Conditions (CHSCT).

A tree analysis was also conducted of the accident causes and the following conservation measures were introduced in order to resume the waste destruction sessions:

– strict compliance with the maximum 25-kg quantity stipulated in the safety report and guidelines, using just a single line no more than 4 cm thick, as calibrated using a tool,

– separate burning for explosives containing metal powder,

– installation of a video recorder onto the existing camera: the objective here was to capture a view of the placement sequence followed for the products to be destroyed, with the precise position before initiation of burning, and the behavioural patterns during the destruction process,

– inspection by a hierarchical superior prior to initiating burning of the targeted explosives,

– creation of “waste orders” associated with each container (25-kg max) to improve knowledge of the total mass of explosives,

– search for a means to split the explosive blocks to be destroyed into smaller units,

– update of both the destruction and waste guidelines.