Segments of a detonating cord exploded during destruction by burning. The well-experienced technician had visually verified the contents of the bags to be destroyed and ensured the absence of any tight knots on the detonating cord. No more than 3 bags were ever burned simultaneously. Burning was initiated by an electric lighter remotely controlled from a blockhouse. On the day of the accident, a few of the shorter detonating cord segments (70 g/m) stemming from the laboratory were burned. After a couple minutes, as the flames were starting to subside, the technician moved away from the blockhouse, protected nonetheless by the barricade all around the destruction zone. At this point, the remainder of the cord exploded, leaving a crater 2.2 m in diameter and 80 cm deep. It was possible that the aluminium covers had remained in place on a few cord ends, although the size of the crater is out of proportion with the equivalent PETN suspected: the initial detonation took place inside the cord, with transmission to products that would have infiltrated underneath the slab concrete. The burning zone was destroyed.

The operator separated burning zones depending on the type of explosive to be destroyed, with each concreted zone being installed on an impermeable layer in order to collect the burning residue and soluble products such as the oxidisers.