In general, the trend has been for companies to move away from the huge all-encompassing sites and to "niche sites". Receiving 10,000 unqualified applications for a job (as has happened in the past to TVA and other large companies in areas where excellent jobs are scarce) is a huge waste of time. Advertising on the company website only reduces the number of applicants, but may miss many that are highly qualified and interested.
I don't think Entergy is advertising on Nukeworker today, but I bet they will be soon (and for good reasons).