Welcome to Science Buddies and thank you for the great questions. First, you should try and get as high grades as you possibly can. Regardless of your pursuits after high school, this can only help. High marks in high school will help when applying to any university. Although you want to focus on Math and Science and get as high of a grade as possible in these areas for a follow on to any Engineering program, many universities look for a well rounded academic resume for acceptance into the undergraduate student body...so don't slack off in your language arts and history classes either. Now as for the college, some universities offer Bachelors of Science programs specifically in Nuclear Engineering and Radiology (NER). However, some don’t, rather preferring to offer the specialty of NER studies at the Master and Doctorate levels. If the university you like doesn’t have an undergraduate NER program, don’t worry, take a Mechanical or Electrical Engineering track. These two tracks will translate and, if you do well, should transition into a Nuclear Engineering Masters program. Whatever engineering track you take, make sure the university and program you choose is Accreditation Board for Engineering and Technology (ABET) accredited. All accredited programs can be found on the ABET website: http://www.abet.org
The key to your questions is research. The link below provides some good information about the Nuclear Engineering career field and has a link to universities that have Nuclear Engineering programs either at the undergraduate, masters, and/or PhD levels. Go to the universities websites to see what the programs offer and require for entry. Also, don’t be afraid to call the university and talk to the admissions officer and departments you’re interested in. The link also has a list of professors who are active in this field. http://www.ans.org/pi/edu/students/careers/
I hope this helps.
"As the circle of light increases, so does the circumference of darkness around it."
~ Albert Einstein