Study On Irradiation Damage Of AP1000RPV Based On Fast Neutron Flux

RPV (reactor pressure vessel) is the primary equipment which nuclear reactor isplaced and has to withstand the enormous pressure when the reactor is in operation. Itis also known that the reactor pressure vessel is the key equipment in the pressurizedwater reactor nuclear power plant, with manufacturing technology standard which isdifficult and cycles and long, and cannot be exchanged throughout the power plantdesign life. While it also has the function of preventing the radioactive material toescape which serves as a significant barrier in the nuclear power plant，and plays animportant role either in the plant economy or safety.The main objective of this subject is to extend the life of AP1000RPV. Throughthe analysis of influence of AP1000pressure vessel material life, the E>0.1MeVneutron flux of radiation damage caused by the pressure vessel, and E>1MeV fastneutron, so fast neutron flux in the E>0.1MeV and E>1MeV are the primary objectof this research. In addition, previous experimental studies have shown that thematerial from the inner surface of pressure vessels to the T/4(T is the thickness ofthe RPV) is much lower sensitivities than from that of the T/4to T/2. Therefore, thestudy of the fast neutron flux in thickness of T/4and the inner surface of PRV (0T)are necessary.About the program of calculations and database applications, this paper focuseson introducing determination programs DOORS3.2series of codes and MCNP5code,and comparing fast neutron flux between DOORS3.2codes and MCNP5code. TheBUGLE-80cross section library which was widely used in pressurized water reactorand the TEXT10cross section library were applied in the two-dimensional TORTDORT and three-dimensional TORT as cross-sectional data. Through the analysis ofPRV fast neutron flux, we can compare the results which were provided byBUGLE-80cross section library and TEXT10cross section library. About MCNP5,the neutron importance is significant in the calculation of large-scale core’s neutronshielding. By simple model experiments, a reasonable choice of neutron importance in different regions has a significant impact on the running time and the accuracy ofthe results.For the extension of AP1000pressure vessel life, measures can be take such asthe improvement of the core fuel management, installation of shielding and othermeasures which can effectively reduce the pressure vessel to accept the fast neutronflux. As for the core fuel management, calculation and analysis about the fast neutronradiation impact on RPV were performed by comparing the low leakage loadingmethod which was widely accepted currently with the Two First Cycle proposed byWestinghouse. The material TiHx, which is considered as high absorption crosssection and high moderator cross section, was inserted between the reactor coreand RPV, which the thickness and position were both the object of this study. Thoughthe Two methods introduced above, the conclusions were achieved.