Thirty years of point group theory applied to reactor physics

A brief survey of applications of point groups to reactor physics is given. First, the general principles of applications of point groups are summarized, this is followed by a short historical review. Two instances of applications in reactor physics are mentioned: the analytical solution to the few group diffusion theory is given based on symmetry considerations. The analytical solution has made it possible to investigate Selengut’s principle and conclude that in general, in the solution process in region D it is not possible to replace a heterogeneous domain Dh ⊂ D by a homogeneous material so that the solution to the few group diffusion equation outside the replaced part, i.e. in D−Dh would remain unchanged.