In this paper, the application of a nondestructive magnetic testing method is analyzed for neutron irradiation-generated embrittlement of nuclear pressure vessel materials. It was found that in spite of the big scatter of measurement points, the degradation of reactor pressure vessel steel can be successfully predicted by this technique. Furthermore, it turned out that the embrittlement highly depends on the local material conditions, which was found to be very different even within the same block of reactor steel material. This implicates different trajectories of their neutron irradiation induced degradation, as well as identifiable differences in the outcomes of their nondestructive evaluation. The magnetic descriptor results add reliable and precise determination of local embrittlement in the material than the traditionally used destructive mechanical parameters, so the results can be helpful for the future practical application of this technique for regular inspection of nuclear reactors.