Quiet/Secluded Beach in Costa Brava/Catalonia

Good afternoon all,
My wife and I have never been to a nude beach and would very much like to try it out.  We are headed to Barcelona in mid-September and wondered if anyone could recommend a quiet/secluded nude beach anywhere between Valencia to the French border.
It's not that we don't expect to be seen, but rather that a quieter place would seem better to start.
Any suggestions are greatly appreciated.