【作者】 陈伟；

【导师】 李智慧；

【作者基本信息】 四川大学 ， 核能与核技术工程， 2021， 硕士

【摘要】 乏燃料后处理工艺中萃取剂及其萃取体系的α辐照稳定性研究,对核能的发展和乏燃料再利用具有重要意义。基于粒子加速器产生α辐照源是常用方案之一,其优势是引出束流稳定、连续。四川大学拟建造的α辐照装置,要求将回旋加速器引出的流强为20μA、能量为30 Me V的α束流降低到9 Me V,降能器上沉积的束流功率为210 W。同时为了保证实验终端维持较低的辐射剂量,以便于实验人员随时进行操作,在降能器之后,还需要进行约十米的传输并且对束流能散进行限制才能到达靶室。降能器系统不仅降低束流能量,也会使得束流能散和发射度增长,而这些束流参数的改变导致束流有较大的损失,实验剂量下降,同时也会对环境、降能器性能、真空等造成影响。论文采用SRIM和G4beamline程序进行了物理计算和模拟仿真,详细地分析了薄膜厚度和材料对束流性能的影响,提出了金刚石应用于薄膜降能器的技术方案,确定了降能器系统的水冷结构和机械结构。降能器物理设计中,根据带电粒子与靶物质的相互作用,确定了降能器厚度,并且对比分析了α束流穿过不同材料后束流能量、能散、发射度的变化,以及与降能器相互作用后次级粒子产额的情况,综合考虑209μm的金刚石为降能器最优选。降能器系统工程设计中,论文完成了降能器热分析和机械结构设计。论文采用CST Thermal&Mechanics模块对降能器水冷结构进行了数值建模与仿真模拟,确定了水冷与薄膜固体的冷却结构、水冷参数,得到了降能器温度分布和材料热导率的变化关系。设计了固定式、直接插拔维护的降能器机械结构。论文采用Tracewin对输运线做了束流光学设计和传输元件参数设计,输运线总长度约10 m,由八台四级磁铁和两台二级磁铁构成,终端束流能量9 Me V,能散0.35 Me V,传输效率为32.5%,均满足辐照平台的技术指标。更多还原

【Abstract】 The research on the alpha radiation stability of the extractant and its extraction system in the spent fuel reprocessing process is important for the development of nuclear energy and the reuse of spent fuel.It is one of the commonly used schemes to generate alpha radiation source based on a particle accelerator for its stability and availability.The alpha irradiation platform to be built at Sichuan University is based on an existing cyclotron,which can provided alpha beam with beam current more than 20 μA and energy 30 Me V,which requires a beam transport system to transport the beam to the target and deduce the energy down to 9 Me V at the same time.The beam power deposited on the degrader is 210 W.The energy degrader system not only reduces the beam energy,but also increases the beam energy spread and emittance.Therefore,the physical design and thermal analysis of the energy degrader are necessary for energy degrader design.In this thesis,the author uses SRIM and G4 beamline programs to compute physical calculations and simulations,analyzes in detail the influence of film thickness and its material types on beam properties,proposes the possibility of applying diamond to thin film degraders,and determines the water cooling of the degrader system structure and mechanical support structure.Based on the interactions between the charged particles and the target material,the thickness of the degrader is determined,and the changes in beam energy,energy spread,and emissivity after the alpha beam passes through different materials are compared and analyzed,and the productivities of the secondary particle yields are obtained.After comprehensively considering all the effects,the 209 μm diamond is selected as the most preferred degrader.The author finished the thermal analysis and mechanical structure design of the energy degrader.The CST Thermal & Mechanics module is used to model and simulate the water-cooling structure of the degrader,the cooling structure and water-cooling parameters of the water-cooling and thin-film solids are determined,and the relationship between the temperature distribution of the degrader and the thermal conductivity of the material are obtained,the direct plug-in structure is adopted in energy degrader mechanical structure designing.The beam after the energy degrader is transported to the experimental terminal target chamber Through a more than 10 m long beam transport line with 8 quadrupole magnetic lens and 2 dipole magnet.The Tracewin simulations indicates that at the terminal the beam energy is 9 Me V,the energy spread is 0.35 Me V,and the transmission efficiency is 32.5%,which all meet the expected technical requirements.更多还原