Two French ski guides were killed Friday in an explosion as they prepared to detonate dynamite to clear a potential avalanche from a slope in the French Alps, police said. The pair, a man and a woman, aged 39 and 33, were working at the La Toussuire station in Savoie to clear dangerous snow drifts before ski runs opened for the day. An inquiry has been launched to discover the cause of the blast. http://www.ottawacitizen.com/news/Explosion+kills+guides/2620588/story.html

All the other information I’ve thus found has been in French:

http://www.ledauphine.com/drame-a-la-toussuire-savoie-ils-voulaient-declencher-une-avalanche-deux-pisteurs-secouristes-tues-par-leur-charge-d-explosif-@/index.jspz?chaine=26&article=268198

http://www.ledauphine.com/la-toussuire-apres-la-mort-des-deux-pisteurs-secouristes-la-piste-des-cr-tes-restera-fermee-@/index.jspz?chaine=26&article=268634

http://www.ledauphine.com/le-declenchement-manuel-pour-securiser-les-stations-@/index.jspz?chaine=26&article=268191

The first Dauphine article states that a new system of explosive fuse called “Nonel” was being used, and that this is supposed to be safer than traditional slow burn fuses or electric fuses. Several other resorts in Savoie had called off manual charge releases Friday morning and were keeping pistes closed instead.

There are no firm details of the circumstances of the explosion, poor weather conditons quickly covered any evidence and forensic specialists were not able to access the scene due the danger of the situation. The pistes in this area of the resort remain closed whilst investigations continue.

Thanks for posting the links, it is a really horrible accident and highlights that a ski patroller’s life is both hard and dangerous at times. The Stéphane “Stif” Lacour was from the Pont de Vaux in the Ain (on the west side of the Jura). He had worked as a pisteur at Prapoutel just across the valley from me. His partner and girlfriend Laurence was from the valley.

They were setting off a 2.5kg charge using the new Nonel system which is supposed to be safer. I don’t know what the explosive was (the papers say a stick of dynamite) but Lacroix (http://www.lacroixds.com), who commercialize the Nonel system in France that you mention also sell a liquid explosive called Secubex. It is quite interesting, consisting of two clear liquids that are safe when stored separately but make a high explosive when mixed (2.2l of Secubex is the same as 1.25 kg of TNT). The liquids could be stored in drinks bottles and smuggled onto an airplane - which is probably why there has been a big panic about this kind of risk at airports. Lacroix also make avalancheur systems.

The big advantage of the Secubex system for ski areas are less regulation surrounding their storage as they are kept separate the the explosive is effectively manufactured on site. There have been problems with ETA terrorists obtaining mining explosives (indeed some ETA people were arrested recently in the Maurienne where this accident occured).

Nonel itself consists of a length of a hollow tube coated with explosive. When ignited it propogates a low force explosion which travels at around 2000 m/s along the length of the tube to trigger a detonator. It eliminates the problems of electrical systems and stray signals but in this case it would appear that either the charge autoexploded or the Nonex system was triggered before the pisteurs could get a safe distance from the charge.