It's... complicated, but in a nutshell, yes, it's unpopular . The closest thing we have to data would be polls [1], which shows that the view is now positive only for a minority (although the ratio is 47 / 53, so you might say it's "slighly" unpopular.)
It's clearly became a purely political and partisan topic though ; the right-wing, older and upper class will be more favorable than the left-wing and youngster.
The French Green party, the most "visible" NGOs, left-wing press and public media are (rather) openly against nuclear.
Right-wing press and the industry is only slighly more favorable. Quite surprisingly, even the far-right movement is going "full nuclear" those days.
A large part of the population is concerned by security and the handling of nuclear waste ; and too many believe that our nuclear plants are contributing to global warming [2].
The debate is not going to get better any time soon, as we're about to reach both the end-of-life of the 40-year-old plants, and... an electoral year.
> Quite surprisingly, even the far-right movement is going "full nuclear" those days.
Just to clarify, it's "surprising" because they can be quite sceptical about science (the leader of the "main" far-right party has made comments about covid vaccines that borders on conspiratism ; the "smaller" far right parties are crossed the border a long time ago. )
They're trying something that is being more "anti-wind" than "pro-nuclear", which makes sense as they want to gather votes from the southern countryside with is heavily biased against wind turbines.
We'll see how that fares next year when they have won the election.
If I'm parsing this correctly, you mean that nuclear power is unpopular in France?