The physics of deuterium-fueled tokamak reactors and a transport code, DDMAK, developed to model them are described. Two examples of work done with this code are presented. In the first, the possible temperature profile broadening effect of synchrotron radiation is examined quantitatively and found small. The second example is a study of the importance of nuclear elastic scattering (NES) in the context of a deuterium-deuterium reactor plasma. Although there are some differences in the DDMAK results due to NES, the overall effect is small. Still the calculational methods may be important for future, more demanding cases.