Alain, so many things to reply on, but I'll pick a few:
Many nuclear plants similar to Garona have been licensed to operate for 60 years, so at 41 the plant is far from "old".
I would hardly trust financial claims by industry trade publications. If wind were cost effective without government subsidies then why have new projects gound to a halt since Spain stopped issuing new feed in tarrifs?
Every nuclear plant unit employs between 800 and 1000 full time employees. In addition, local skilled labor works to supplement full time staff for projects and during refuelling outages. Then there are jobs in local and regional businesses that provide materials, supplies, and parts. Finally there jobs created by the increase in economic activity in the communities around the plants when the plant workers spend their earnings. The eight nuclear plants easily produce tens of thousands of direct and indirect jobs.
Why will the loss of Garona's 446 megawatts result in an increase in coal or gas imports? Because Spain has no choice - nuclear is base load / always on energy that can not be replaced by renewables. They have to get the new base load energy somewhere.
Actually they do have a choice - their other option is to let the grid go dark when the wind isn't blowing or the sun is not shining.