In a 15,000-tonne capacity flat silo, fire broke out at 10 pm on 8,000 t of rapeseed being drained following a suspicion of heating. The transfer is proceeding via chain conveyor belt, fed by 2 hatches placed away from the suspected hot spot. Once the building access door is released, a loader is used to put in material through these 2 openings. The facility manager noticed flames upon returning from a 5-min break taken in the site offices with staff members. Municipal first responders are called; fire-fighters extinguished the blaze by 10:40 pm and then monitored the rapeseed stock with a thermal camera, for the time needed to devise a strategy to remediate this heating issue. The transfer of product not affected by the fire outbreak resumed at 11:15 pm using the chain conveyor belt combined with a systematic initial verification of seed temperature. First responders remained on-site through 10 pm the day after confirming the absence of residual risks. The burned rapeseed and immediately adjacent zones has been evacuated to the courtyard along with the loader at the beginning of the morning. The silos were completely drained over the subsequent days, with all merchandise being cleaned prior to shipment to customers (10 to 12 lorries/day). A conveyor belt located near the upper footbridge plus lighting and electrical cables have sustained damage. Two rows of the silo’s translucent roof tiles melted from exposure to the heat, and 500 t of rapeseed were lost.

According to the silo operator, this loss had been caused by self-heating of the rapeseed, whose humidity had led to the formation of seed columns beneath the conveyor belt shelf. The year’s odd weather patterns resulted in a harvest with differing maturity stages within a given parcel and higher impurity rates. Compliance with seed acceptance and processing procedures (cleaning and, if necessary, drying) made it impossible to avoid this heating phenomenon. The silo thermometer had failed to detect any anomaly, and staff had been alerted due to the smell of hot grains inside the silo. Running the ventilation for several nights, in order to cool the stored pile, had most likely accelerated the heating phenomenon that was already well underway.

The operator issued an in-house memo on the accident and reinforced the monitoring of storage areas at its other sites. A consolidation of rapeseed acceptance procedures, to address the case of unfavourable weather conditions, was also scheduled over the next few years. The inspection authorities for classified facilities asked the operator to: improve the site’s fire response protocol, introduce extinguishers into the flat silo and heed its obligations regarding accident/incident declarations.