Simplify the following text for a Grade 15 native English-speaking person.
Original: Nuclear engineering also includes the study of nuclear fusion , medical and other applications of radiation , radiation safety , heat transport , nuclear fuel and other related technologies , nuclear proliferation , and the effect of radioactive waste or radioactivity on the environment .
Simplified: The field also includes the study of nuclear fusion , medical and other applications of ( generally ionizing ) radiation , nuclear safety , heat\/thermodynamics transport , nuclear fuel and\/or other related ( e.g. , waste disposal ) technology , nuclear proliferation , and the effect of radioactive waste or radioactivity in the environment .