Study On The Effect Of Irradiation Cavity Swelling In SIMP

Structural materials used in future advanced nuclear facilities have to withstand harsh environment,such as strong radiation damage,high temperature,stress and high He accumulation leading to radiation swelling,precipitation,embrittlement and other behaviors affecting the safety and reliability of materials.Materials with excellent performance are desired to meet the safe and efficient operation of the advanced reactors.Due to their high resistance to radiation swelling and creep,low thermal expansion coefficient and activation,F/M steels proposed as promising candidate structural materials have been recognized internationally.Therefore,it is of great significance to study their resistance to irradiation,especially the resistance to irradiation swelling for their application in future advanced nuclear energy system.This work used He/Fe ions beams provided by both 320KV multidiscipline research platform for highly charged ion and low energy accelerator facility to irradiate four types of steels(SIMP,T91,MA956 and Eurofer-ODS)at different temperatures regimes.Through the transmission electron microscope(TEM),optical metallographic microscope(OM),nano indentation technique(NIT),systemic research for the microstructure evolution of material surface and radiation damage zone,radiation hardening behavior,as well as the resistance to irradiation swelling of these steels are given.1.Voids swelling in SIMP and T91 steels under high dose Fe ion irradiation(100appm He and 0ppm He)was investigated.The results showed that the swelling was significantly promoted by the pre-injection of He,and the swelling changed with temperature as follow:S_440?>S_450?>S_460?>S_420?.The irradiation induced peak temperature of void swelling of two steels is about 440?.When the temperature increased to 470?,the irradiation induced the formation of high-density rod-like precipitates,but no cavity was formed.In general,the resistance to swelling of SIMP steel is more excellent than T91 steel.2.The irradiated swelling behaviors of SIMP,Eurofer-ODS and MA956 steels implanted with He ions were studied.Compared with self-ion irradiation,the temperature range of swelling by He ions irradiated is wider,and the incubation period of irradiated swelling reduced,moreover,the peak temperature of irradiation swelling moved to a higher temperature.Under the condition of 1×10¹⁷ions/cm²He injection,S_600?>S_500?.At 600?,large voids and cracks appear in SIMP steel.When He implantation dose increased to 2.5×10¹⁸ions/cm²,large voids and cracks appeared in all three steels.3.The hardening behavior of Fe ion-irradiated SIMP and T91 steels(100appm He preimplantation and no preimplantation)was studied.The irradiation induced hardening has been found in the two steels.The relationship between the hardening with temperature is:?H_450?>?H_460?>?H_440?.In addition,the irradiation hardening trends of the pre-injection He samples is similar with that of non-injection He.