Again, "back in the day", a high school diploma and passing the POSS got you in. We have some 45 year old operators with those qualifications. But not anymore.
All of our new hires at Exelon have at least the equivalent of an Associate's degree, or are ex-Navy nukes.
My son, with a B.S. in Biology and some post-graduate credit hours, passed the POSS and was interviewed along with 25 other people for 10 NLO openings. My fingers are crossed! So the degree and POSS are not a sure thing, but they open the door.
Our last NLO class had 1 Chemist, a Mechanical Engineer, a Biologist, an Astronomer, a guy with a degree in Animal Husbandry (yep, a B.S.) and 5 ex Navy Nukes in it. The class before that was similar, with the only person without Navy or degree was 1 semester short of a BS in Physics.
There are some 2 year programs that are tailored to the industry. Linn State in Missouri has some programs for Operating, RP and Maintenance. There's a college near Toledo Ohio that partners with Davis-Besse.
As an NLO, you are in the licensing path at most utilities. It costs $500K to $1M (depending on who you ask and how they do the accounting) to license each person. We choose our license candidates carefully these days! If you aren't academically inclined, you may want to reconsider your career path. NLO training lasts about a year, License training takes nearly 2 years, and you are back in Training every month and a half for a week of continuing training as an NLO or RO. Lots of studying, lots of tests.
Call the HR department or the Training Department at Commanche Peak or South Texas Project, since you are interested in a Texas utility. Ask them what their requirements are. I think you'll find you need an education. Pretty much any BS technical or science degree, or an Associates that is a good fit. Or the Navy, but that's a whole different story!