An explosion occured in the (detonator) cap loading line room in one of the buildings at Orica Sweden AB’s plant in Gyttorp. In the cap loading line room detonators are filled, and pressed, with explosives and delay composition. One operator was in the cap loading line room when the explosion occurred and the operator suffered fatal injuries. The accident took place at the time of a shift change, but there were no witnesses to the accident. There were no damages outside the cap loading line room. Orica Sweden AB in Gyttorp manufactures detonators and ammonium nitrate based explosives and emulsions for the mining industry and the construction industry. The plant in Gyttorp has approximately 270 employees. Orica is listed on the Australian Securities Exchange and has around 11 500 employees in total. The accident took place in the cap loading line room where detonators are filled and pressed with explosives and delay composition. The process is fully automatized and no operators are in the room when the process is in progress. The detonators moves automatically between different stations for filling, and pressing, of the detonators with explosives, PETN (pentaerythritol tetranitrate) and hexogen, and delay composition. The operators only intervene with the process to do tasks under controlled circumstances. The equipment in the room for filling the detonators is connected with the entrance to the room. When the door to the entrance is opened the filling process and equipment stops in a safe mode. The building where the room is located is constructed with thick walls and built to cope with possible explosions. According to the documented working instructions the equipment shall be emptied of explosives before any kind of cleaning or maintenance take place. The other operators in the building evacuated and called SOS. The emergency service was first on the scene of the accident at 0545. They entered the cap loading line room where they found the deceased. All work at the plant stopped after the accident. The building and the cap loading line room was shut down in order to secure the work environment and the forthcoming accident investigation. The police then took control over the building to investigate the accident according to the Penal Code and the Work Environment Act. Orica’s local crisis management team was mobilized immediately. Their task is to facilitate cooperation between the authorities and to support the staff and the society under such circumstances. Orica gathered a team of senior executives and technical specialists from other departments in Orica’s international organization. The accident investigation followed the Incident Cause and Analysis Method (ICAM). Based on evidence collected to date, it is believed from the company’s investigation that the most probable sequence of events was:

· Initiation: a friction event was caused by rotation of a bolt on PETN hopper flange using a steel spanner. This action is likely to have resulted in initiation of residual PETN.

· Propagation: the initiation propagated from the bolt area inwards towards the PETN hopper.

· Mass Explosion: PETN hopper had not been emptied of inventory prior to maintenance. It is estimated that mass of PETN in hopper was approximately between 250 and 750 grams. Propagation resulted in mass detonation of PETN in hopper. At the time of the explosion the process and the filling station wasn’t in progress. The logs doesn’t indicate that there were any problems with the filling station. Orica has focused the measures to make the handling of the explosives safer, improve the instructions and increase the staffs’ awareness of the importance to follow instructions and the possible consequences. Friction, Impact, Static, and Heat (FISH) events with sufficient energy to cause detonation need to be identified and eliminated. Note that energy from FISH events required to initiate primary and secondary explosives is significantly lower than that for Packaged Explosives products and intermediates. Energetic Material: All equipment that contains/has contained energetic material must be removed and cleansed of all energetic material prior to undertaking:

· any maintenance work on process equipment at all Initiating Systems (IS) plants; and

· hot work on equipment at any plant. This has for instance involved improvements such as:

· Changed metal parts on the equipment to plastic to avoid metal to metal.

· No tools are required to open, change or adjust the dosage of the explosives. It can be done with pinches. Independent verification and sign-off is required prior to commencing the work described above. Permits: Any work required on Initiating Systems equipment (whether by maintenance or operations) that contains/has contained energetic material, if that work could result in any FISH event (e.g. use of metal tools, any heat source), must be treated as ‘hot work’ and must be authorized through the site’s Hot Work Permit process.