In France, on the news, we have had Gérard Feldzer (retired air france captain and director of the bourget air and space museum) who have given this explanations for the fire absence :
- Wings didn't separate from the fuselage, so no leak of fuel
- Pilots certainly had done their emergency checklist before the crash and shutoff the fuel levers.....
Shuting off both fuel levers is done in a predicted crash just before touching down, but I don't think that in this case, they have had the time to do this procedure........