As an example of my thought process :-
"The first Rule with Health & Safety is to remove the hazard.!
Only if you are unable to remove or make safe the hazard do you resort to other "protective measures".
I think that same rule applies in this instance with your bees.
If the wasp nest (let's call it the the hazard) is removed you should not need to attempt other drastic actions to protect the Nuc (your persons at risk).
Although wasps have a place on the eco system and can be very beneficial in the garden, if there are too many of them and they are causing damage, they most definitely need culling.
I'm with Mr Wilco on this. Find that wasp's nest - there may be more than one.
Wait til dark and destroy it/them.
Your bees will be able to get on with surviving without being continually robbed.
Malcolm B.