qfmike737
Normal SOP would be for the Captain to advise the passengers that they were going to dump fuel in order to return and land at a reasonable weight. That there was no emergency, just a technical problem that made a return the safest option and that all passengers would be attended to and onward flights arranged with the minimum of delay.
It would be quite a busy time on the flight deck so announcements would be sufficient to calm any passengers fears, be factual and helpful but they would not get a running commentary!
The captain would call the senior CC to the flight deck and keep them fully up to date and informed of what was happening, in this case, since it is not an 'emergency' there would be no need to brief for an evacuation.