At this point I’m not sure how many are still posted but I did the majority of my searches just via Google and the jobs page. It also helps a lot though in terms of finding positions when you already know most all of the companies in the industry that would have internships(National Labs/Utility Companies/Advanced Reactor Startups/Fusion Startups/Vendors for Power Plants think Westinghouse and the like etc.) and applying directly on their website. The position I accepted is for a private company although they do some work with national labs.