In a nuclear materials processing plant, the recovery operation on a set of old cylinders containing fluorine was ongoing; their contents were intended for inerting along with cylinder disposal. An ignited fluorine gas leak occurred on a manual valve of the product return system and burnt the hand of the technician handling it. A second plant technician, who intervened with a fire extinguisher to put out the blaze, experienced irritation in the throat. The occupational medical service took care of the 10 workers present in the vicinity of the installation who had likely inhaled fluorine. The operator estimated the amount of fluoride released into the atmosphere at 5 kg. The valve and a section of the pipeline were destroyed.

This type of accident had already occurred on the site, and the operator offered two hypotheses: an inerting malfunction of the pipes and valves of the recovery system and/or a far too high speed of fluorine gas likely to breakdown the passivity of the metal and make a hole in it causing an ignited leak. The operator considered the second hypothesis more plausible.

The Classified Facilities Inspectorate and Labour Inspectorate visited the site on 14th December and found that the risk of fluorine leakage and induced thermal effects, although well known to the operator, had not been sufficiently taken into account: the existence of a manual valve, even though a pneumatic valve was recommended; no protective screen between the valves, pipes and technicians; non-fire-proofed gloves distributed to technicians; respiratory protection equipment not worn; no system for directing and capturing any accidental leaks for which the maximum potential consequences have not yet been assessed; and the document indicating the principles for handling such an operation failing to meet quality criteria. The operator was therefore required to interrupt the recovery operations for inerting until submitting the findings of its investigation into the causes of the incident and to correct the malfunctions observed, notably by implementing action systems and remote viewing, and installing a ventilated anti-contamination tent over the entire return circuit to collect any toxic gas leaks and channel them to an appropriate waste destruction system, etc.