CiADS中LBE散裂靶的放射性核素研究

铅铋合金(LBE)作为中国加速器驱动系统(CiADS)散裂靶的候选材料，长期辐照使其具有很强的放射性。散裂靶放射性核素的研究仅考虑了质子束的散裂反应，而忽略了反应堆裂变中子的活化作用。本文采用FLUKA和MCNP耦合计算LBE和及其结构件的放射性产物。比较了裂变中子和高能质子在放射性产物的活度、主要放射性核素、毒性和衰变光子等方面的贡献。裂变中子的活化作用对主壳、导管和射束管有显著影响。当反应堆趋于临界状态时，裂变中子对LBE的活化作用是高于质子束流的。在LBE中，96.66%的 210Po是由裂变中子诱导的。这些结果表明，裂变中子在LBE及其结构部件的活化计算中是必不可少的。此外，本研究为CiADS的辐射防护提供了参考数据，也为ADS系统中散裂靶的放射性核素研究提供了更准确的方法。

Radionuclides Study of Lead-bismuth Eutectic Spallation Target in CiADS

Lead-bismuth eutectic(LBE) is the candidate material of spallation target for China initiative Accelerator Driven System(CiADS). Long-term irradiation makes the LBE highly radioactive. Most of the spallation target radionuclide studies focused on the effects of the proton beam and ignored fission neutrons from the reactor. In this paper, both the fission neutrons and the high-energy protons have been taken into account in the radionuclide calculations of LBE and spallation target structural parts by coupling codes FLUKA and MCNP. Contributions from the fission neutron and the high-energy proton have been compared in the aspects of the activity, main radionuclides, toxicity, and the decay photon of radioactive products. The main shell, guide tube, and beam tube are significantly affected by the fission neutron activation. When the reactor tends to be critical, the fission neutron-induced LBE target activations are even greater than that induced by the proton beam. In the LBE itself, 96.66% of 210Po is induced by the fission neutrons. These results illustrate that fission neutrons are also essential for the radionuclides calculation of LBE and its structural parts. In addition, this study provides reference data for the radiation protection of CiADS and a more accurate method for the radionuclides study of the spallation target in ADS systems.