Keywords: irradiation damage evaluation, neutron flux attenuation, reactor pressure vessels, RPV azimuth, experimental simulation, VVER reactors, nuclear power plants, nuclear energy, biological shielding, attenuation dependence
Neutron fluence attenuation through VVERs and mock-ups of reactor pressure vessels
The calculational results of neutron flux attenuation through the Reactor Pressure Vessel (RPV) of VVER type of reactors of Kozloduy NPP and their LR-0 mock-ups have been compared. The neutron flux with energy above 0.5 MeV has been considered. For the VVER-440 the neutron flux attenuation through the RPV and its mock-up has consisted within the calculation uncertainty. For the VVER-1000 the neutron flux attenuation through the RPV and its mock-up has consisted also within the calculation uncertainty except the region behind RPV where the attenuation difference has been significant. It has been demonstrated that this difference is due to the difference in the biological shielding materials. The mock-ups of VVER-1000 and VVER-440 types of reactor could be used for experimental simulating of the neutron flux attenuation in the nuclear power plants taking into account the existing peculiarity of the biological shielding and the attenuation dependence on the RPV azimuth.