Investigation Of Radiation Effects In Beam Window Materials For Use In ADS Spallation Neutron Source System

Radiation effects have been investigated up to -30 dpa by the heavy ion irradiation simulation and positron annihilation lifetime techniques in the home-made modified 316L stainless steel and the commercially available stainless steel and tungsten, which are used as the beam window materials for the spallation neutron source in Accelerator Driven Radioactive Clean Nuclear Power System (ADS). Their radiation resistance properties are compared.It would take several hundred days to reach such a high dose by using currently available proton and neutron sources, while only several hours to several ten hours by the energetic heavy ion irradiation. Therefore, the heavy ion irradiation simulation is adopted in the present experiment. In order to verify the reliability and validity of the heavy ion irradiation simulation of neutron and proton irradiations, radiation damage and its thermal annealing behavior in a-Al2O3 irradiated at the equivalent dose by 85MeV 19F ions and by En> 1 MeV neutrons, respectively, are studied. The experimental results show that the produced radiation damage and its thermal annealing behavior are the same for both irradiations in a-Al2O3, and that the heavy ion irradiation can well simulate the neutron and/or proton irradiation.Heavy ion irradiation of 80 MeV 12C or 85 MeV 19F is used to simulate the proton and neutron irradiation of the beam window materials for ADS. The irradiation effects are examined by the positron annihilation lifetime technique. The experimental results show that the large-size voids are created in tungsten irradiated to 20 dpa, the 10-vacancy voids are observed in the commercial stainless steel irradiated to 22.8 dpa, and the 5-vacancy voids are detected in the home-made modified 316L stainless steel irradiated to 30 dpa.A comparison of radiation resistant properties for the home-made modified 316L stainless steel and the commercially available stainless steel and tungsten demonstrates that the radiation resistant property of stainless steel is much better than that of tungsten, the stainless steel is a good choice for the beam window material of the ADS, and the modified 316L stainless steel is the best choice.