Google 'TVA HU Tools' and look at the top hits. Being able to weave things such as self-checking, procedure adherence, etc., into the interview would be a good thing.
This is a SUPER suggestion, and I'll even go a little further and post a link to what this guy is talking about.
http://multi.tva.gov/contractor/instructors/ATIS00076300/HU_Tools_Student_Handout.pdfThe STAR interview technique brought up by Papa Nuc is also a good bit of advice - have a story ready to tell about a problem you have faced in another job and how you resolved it. As specific as possible.
Dress code is 'business casual' for these interviews. Personally, I wore a long sleeve button down shirt with a tie, no sport jacket - but that was probably overdoing it. Google business casual for women if you want pics.
At the end of the interview there will be an opportunity to ask questions... DON'T pass this up! I was told at my interview that they were surprised (in a good way) that I had a few questions for them after it was all over. I guess no one else that day had thought to ask any. It wouldn't hurt to bring a small note pad and pen to take notes of their responses to your questions, to show that you are interested in what they have to say about the job. Don't ask too many questions though, one or two should suffice.
Congratulations on making it this far in the process. The last batch of interviews at my plant for this job was ~25 to 30 people. Don't be surprised if it takes some time after the interview before you hear anything back - for me it was 3 more months after the interview before I hired in.
Good Luck!