The presented paper contains the evaluation of dynamic impact influence on integrity, fatigue and service life of highly loaded NPP piping. The analysis was performed on the base of on site measurements of piping operational vibration and strength study of phenomena by methods of fatigue and fracture mechanics. The 3D High Viscous Dampers (HVD) were successfully applied for protecting primary loop piping welding from flaw growth due to operational flow induced vibration as one of the flaw propagation sources, as well as many other primary and secondary part important piping systems were fully protected from hydraulic hammers, seismic excitation, shocks, two-phase flow excitation and other kind dynamic impact.