At around 7:30 p.m., two explosions occurred at a wood panel manufacturing plant. The first occurred in a half-filled 230 m³/30 -m-high silo and the second was triggered in a screener. The wood treatment facilities then caught fire and the flames spread to a second silo. The site’s emergency services and automatic fire suppression system extinguished the fire on the screener. The silos were flooded with water and then drained, but the fire rekindled. However, the spray pipes soon froze and stopped supplying water. The emergency services lost control of the fire. Firefighters, alerted at around 11:00 a.m., cooled the silo and emptied its sweep auger. The 20 employees present were evacuated. A 50 m cordon was set up. The below-zero temperatures caused the site’s fire suppression system to freeze up and created black ice that further hampered operations. The firefighters finished emptying the silo and extinguishing any remaining hot spots at around 3:45 p.m.

The material damage was extensive, affecting the explosion vents, components of the mechanical conveyors, and valves. The site was shut down for nine days. Material damage amounted to €15,000 and operating losses amounted to €800,000.

The explosion was caused by a spark inside the crusher. The spark detection systems downstream of the crusher and upstream of the silo, and which are synchronised with the conveyance speed of the wood chips, were incapacitated by the freezing temperatures. This caused wood chips to build up in the conveyance pipes downstream of the crusher. It modified the speed of the air and wood chips, desynchronizing the detection and suppression system and allowing sparks to pass before water was automatically piped in. A spark then spread to the silo where the first explosion occurred. Flames subsequently travelled up the mechanical conveyor and on to the screener, where the second explosion took place. The fire spread to the second silo via the second mechanical conveyor. The screeners and silos are items of ATEX equipment.

Since the accident, the operator has taken the following actions to improve its response capabilities: it updated its internal emergency plan, it installed an auger under the silo, and it insulated pipes and valves. The operator also plans to overhaul its GreCon system and install an additional detection and suppression system under the screener.