Yeah I do mean energy. Indeed, nuclear energy is big in France and popular among the overall population.

Their stated goal is to eventually go full renewables (0% nuclear in 15-20 years). They want to stop building new plants and eventually close existing ones. Some of the stated reasons are waste, water, an inability to solve climate change, unreliability (such as in 2022 with heat and the war in Ukraine, adding that climate change compounds the heat issue), dangerous accidents, import issues (no uranium in France, therefore does not allow for energy independence), and cost. He's not bad on climate change generally though.

Those were the official reasons I was able to find, I couldn't tell you if there was some kind of ideological stance behind all of it or some kind of sociological explanation that explains their opinions.

He's not the only one, the green party is also against it (0% nuclear in 25 years). The communist party (not communist) likes nuclear energy, the socialist party (not socialist) is kind of split/unclear. The right-wing parties all like nuclear energy. One of the trotskyist parties, the NPA is also anti-nuclear (0% in 10 years), citing Fukushima, Chernobyl, military interventionism in Africa and Asia for uranium, waste, and also call it anti-democratic.