  Since Reactor Pressure Vessel steels are ferromagnetic, they provide a
convenient means to monitor changes in the mechanical properties of the
material upon irradiation with high energy particles, by measuring their
magnetic properties. Here, we discuss the correlation between these two
properties (i.e. mechanical and magnetic properties) and microstructure, by
studying the flux effect on the nuclear pressure vessel steel used in reactors
currently under construction in Argentina. Charpy-V notched specimens of this
steel were irradiated in the RA1 experimental reactor at 275{\deg}C with two
lead factors (LFs), 93 and 183. The magnetic properties were studied by means
of DC magnetometry and ferromagnetic resonance. The results show that the
coercive field and magnetic anisotropy spatial distribution are sensitive to
the LF and can be explained by taking into account the evolution of the
microstructure with this parameter. The saturation magnetization shows a
dominant dependence on the accumulated damage. Consequently, the mentioned
techniques are suitable to estimate the degradation of the reactor vessel
steel.
