Just thinking logically about a solution to protect against this type of event here.
There should always be two safety processes in place, this would allow for a back up. There should be the two vents one in the lower part and one in the roof to vent any gasses, in Ausie I would expect there to be a gause mesh over the vents to stop those scary spiders getting in. The second could be a blast release vent which would minimise the pressure in the event of a blast directing the blast through the roof.
I was at the local supplier only two weeks ago and as another fridgie came in he had just had a cylinder of nitro open up in the back of his ute. Just shows how we can make mistakes sometimes. There have been other reports of exploding refrigerants on this forum, not saying that in the last two cases there is refrigerant involved.