My experience with headhunters was they mostly do not get used for maintenance and operations positions at nuclear utilities. I know that my utility doesn't use them for those positions, though they will for HR and administrative positions. When I was getting out 5 years ago, I used Orion etc and went to several job fairs. The companies present were a beer bottling company out of Atlanta, a paper mill, Wal-mart, a biochemical plant... Things like that.
What I did was to get a list of every nuclear plant in the country (
www.nrc.gov) and find out their websites, or the sites they used for hiring. (IE, Wolf Creek at that time didn't post on their home site, but rather on Kansasjoblinks.com) Then , I set up a rotation where about every 2 weeks I would have cycled through every web site, and kept a kind of ledger of what resumes and cover letters I had submitted, watching for when the postings were closed, and a log of all phone calls I made, and any other contact.
Now, one of those head hunters did turn me on to Westinghouse outage support group, out of PA, which was prob the closest to a nuclear facility that I came to. Lots of travel with that job, though.
Best of luck with your search!
Bill