Hey I am a math major looking to do an REU (and later a masters/PhD.) in nuclear engineering and I am interested in the field of reactor physics. I hear it tossed around a lot but I don't really know the definition of it. I'm taking a radiation physics class next semester at a separate technological university, but I think that it is more related to materials. Does the field of reactor physics cover both fission and fusion? I am guessing you deal mostly with the reactor core in this field. Mainly I want to be able to develop a strong mathematical background and apply my knowledge from linear algebra, functional analysis, and PDE's to some computational problems in Nuclear engineering.