加速器驱动的次临界铀溶液同位素生产堆概念设计

Conceptual Design of Accelerator Driven Subcritical Aqueous Homogeneous Reactor for Isotope Production

加速器驱动的次临界铀溶液系统作为新型同位素生产技术,具有固有安全性高、同位素比活度高及提取工艺简单等优势。本文从次临界系统的基础理论出发,确定了堆芯设计原则,针对加速器中子源和燃料选型进行说明,利用蒙特卡罗程序完成了次临界堆芯的概念设计并给出了一系列设计参数,此外,对堆芯长寿期燃耗特性和^(99)Mo产能进行了计算分析。结果表明,该方案^(99)Mo的年产能可达20 kCi(1 Ci=3.7×10^(10)Bq)以上,考虑运输过程中衰变损失,保守估计可满足全国1/3的临床需求,对后续掌握^(99)Mo生产技术并实现工程应用具有重要的现实意义。

^(99)Tc^(m)is the most widely used radioisotope in the field of nuclear medicine at present,which is used for clinical diagnosis of diseases and research on the structure and function of organs generally.The existing medical^(99)Tc^(m)is mainly obtained through the decay of^(99)Mo generated by irradiating low enriched uranium(LEU)or high enriched uranium(HEU)solid targets in the experimental reactor.There are drawbacks such as complex processes,high costs and long-distance transportation losses.In addition,the global number of medical isotope production reactors is relatively small and most of them were built in the 1950s and 1960s.They face a series of issues such as aging,unstable operation and retirement.The accelerator driven subcritical aqueous homogeneous reactor,which was proposed based on the strengths and weaknesses of producing medical isotopes through accelerators and aqueous homogeneous reactors,has the advantages of high inherent safety,high isotope specific activity and simplified extraction process as a new isotope production technology,making it a research hotspot in recent years.Besides,there is no need to consider the complex and redundant safety protection system in the design,thus the reactor body construction cost is lower and the operation management is more flexible,making it convenient for the simultaneous construction and operation of multiple modular production devices.Based on the basic theory of the subcritical system,this thesis determines the core design principles,explains the accelerator neutron source and fuel selection,completes the conceptual design of the subcritical core by using the Monte-Carlo program,and gives a series of design parameters including k eff,neutron flux density and power.The initial design conditions are as follows:The entire subcritical core is approximately a concentric cylindrical structure,with the accelerator neutron source at the center,following the neutron multiplication layer,the uranyl nitrate solution zone,and the water reflection layer unit from inside to outside.In addition,the long-life burnup characteristics of the core and the^(99)Mo capacity were calculated and analyzed using relevant burnup procedures to demonstrate the feasibility of the plan.The subcritical core scheme has a low power level and is safe and reliable.When the extraction efficiency is 60%,the annual production of^(99)Mo could reach over 20 kCi,which could meet one-third of the present clinical needs of our country with a conservative estimate.All of the above work has important practical significance for mastering the production technology of^(99)Mo and achieving engineering applications in the future.