UIUC Nuclear Physics Lab, University of Illinois, Urbana-Champaign
U of Illinois also has a very good nuclear engineering program. http://www.ne.uiuc.edu/
Purdue University's Nuclear Engineering department has a really interesting program in computational physics. They are working with Argonne National Laboratory on the next generation of reactor simulator.
Triangle Universities Nuclear Laboratory (Duke University / North Carolina State University / University of North Carolina ) NCSU has a good nuclear engineering program as well. http://www.tunl.duke.edu/ at Duke University