Nuclear Power facilities....
Monocock,
I dont know if this is of any help - and Id like to point out that I dont know the specifics of any zones in Cherbourg - but I do know that as of a few weeks ago, there are now new 5km radius and 3300ft high exclusion zones around most (I think all) Nuclear Power facilities in France. There were definitely NOTAMs for the two in my area at Blaye on the Gironde estury and Bague just south of Bordeaux.
Regards, SD..