Mont Louis

The incident

On 25 August 1984, the Mont Louis, transporting 30 drums of uranium hexafluoride, was northbound in the English Channel shipping lane, bound for Riga in Latvia. That day, mist came down, severely reducing visibility. A collision occurred off the coast of Ostend (Belgium) between the Mont Louis and the German ferry Olau Britannia. The bow of the Olau Britannia became deeply embedded, by over six metres, in the side of the Mont Louis. Water poured into the ship’s engines. The crack was so wide that the Mont Louis was at risk of capsizing if the Olau Britannia were to be pulled away. Indeed, when the two hulls were separated, the Mont Louis began to list, tipped onto its side, and finally sank in waters 14 metres deep. This incident was a major concern as the ship was transporting a hazardous substance: uranium hexafluoride. This is an intermediate substance in the process of uranium enrichment. A month after the collision, all 30 drums of uranium hexafluoride had been recovered.

According to investigations and witness accounts, the French vessel was entirely responsible for the collision. The commanding officer and his first lieutenant were accused of having cut in front of the German vessel and having left their radar set to 3 miles rather than 6, which would have alerted them as to the danger earlier.

Response

To respond to the oil from the ship’s bunker tanks which had partly been spilt into the sea, the Belgian Navy sprayed 28,000 litres of dispersant.

Impact

After this collision, no increase in the level of radioactivity was reported in this area. In point of fact, uranium hexafluoride is a non-toxic, crystalline chemical in the state in which it was transported in the drums. It is only when exposed to humidity that the chemical gives off a toxic cloud of acid which can prove lethal within a radius of 150 m.

Sources:

- HOOKE, Norman, 1997, Maritime Casualties 1963-1996, second edition, LLP Limited, Londres
- T.G. Jacques and F. Delbeke, 2008, Accidental marine pollution in Belgium: The emergence of repose strategies
- Cedre, 1984, Rapport annuel
- Yves van der Mensbrugghe Yves, L'affaire du Mont-Louis - Une cargaison dangereuse, une épave gênante. In: Annuaire français de droit international, Volume 30, 1984. pp. 853-863.