质子引起天然铀裂变产生医用同位素钼-99的研究

医用同位素锝-99m(99mTc)被广泛应用于核医学领域,其主要来源于母体核素钼-99(99Mo)的衰变。但是目前国内99Mo基本依赖进口,通常出现99Mo不能稳定供应的现象。为解决这个重大问题,实现国内99Mo自主化生产具有重要意义。本文基于中国科学院近代物理研究所强流超导直线加速器(China ADS Front End,CAFE)提供的质子束流辐照天然铀靶件,主要开展铀裂变产物中医用同位素99Mo的高效化学分离、纯化及99Mo/99mTc发生器的制备。研究表明:通过α-安息香肟(α-BO)沉淀分离99Mo后,杂质核素去除率大于90%,99Mo的回收率大于90%。通过对99Mo沉淀进行纯化后,大部分杂质核素被去除。提取的99Mo被装配为99Mo/99mTc发生器,发生器淋洗曲线表明:99mTc产品收集在8 mL生理盐水内最为适宜,同时,99mTc回收率大于80%。电感耦合等离子体发射光谱仪(ICP-OES)测量结果表明,99mTc产品中Al、Mo以及U含量极低;同时,99mTc产品的γ谱图中未出现99Mo和其他杂质核素的γ能量峰。以上研究结果可为国内基于加速器辐照天然铀生产99Mo提供技术参考。

干馏法从铀的裂变产物中分离^(131)I

^(131)I是一种重要的医用放射性同位素,但因湿法分离技术上的缺陷,使得从铀裂变产物中获取^(131)I的工艺具有环境污染严重、提取效率低的缺点。因铀裂变产物中^(131)I的产额较高,为拓展^(131)I的获取途径,提高铀裂变产物的利用效率,开展铀裂变产物中^(131)I分离的新工艺研究十分必要。与传统湿法分离工艺不同,本工作采用了干馏法进行铀裂变产物中^(131)I的分离。为了得到高的^(131)I分离效率,将分离过程分为低温粉化、高温干馏和中低温保温三个阶段,并研究高温干馏阶段温度对^(131)I分离效率的影响。实验发现:当干馏温度高于950℃时,^(131)I的分离效率≥98%。此外,研究结果还表明,在该干馏温度下,碘和^(103)Ru均可挥发出铀靶片,但产物收集液中却仅含有碘。为了解释这一现象,对碘的分离过程进行分析,结合实验结果和理论计算,推测挥发物中碘和^(103)Ru分离的原因为:^(103)Ru与氧反应生成挥发性RuO_(4),从铀的裂变产物挥发出;因加热管内温度较高,RuO_(4)在迁移过程中发生了分解,生成RuO_(2)沉积在加热管内部。因此,利用干馏法从铀的裂变产物中分离^(131)I时,为了得到放化纯度高的碘产品,不仅要合理规划分离过程,还需科学设计加热管的长度。

2-22 Study of Oxidation/reduction Volatilization Technology

As an advanced dry head-end processing of spent fuel reprocessing, the oxidation-reduction volatilization technology will use for pulverizing uranium oxide ceramic pellets, decladding, and removal of most of volatile and semi-volatile fission elements, 3H, 14C, Kr, Xe, I, Cs, Ru and Tc, from fuel prior to main treatment process. The AIROX and ORIOX process, including circulation of oxidation in oxygen atmosphere and reduction in hydrogen atmosphere, researched on international at present, is considered to be the first choice for head-end processing.

2-27 A Density Functional Theory Study on Amide-substituted Phenanthroline Ligands for the Separation of Lanthanides and Actinides

As the novel ligands for the separation of trivalent actinides from lanthanides for spent nuclear fuel reprocessing,the amide-substituted 1,10-phenanthroline derivations were found to have high selectivity on Am(III) and Eu(III) in nitric acid media[1;2]. However, the origin of their extraction abilities is still an open question.

2-23 Research of A New Triazoly-pyridine Ligand for Lanthanide/Actinide Extraction

If high level radioactive waste (HLW) is directly disposed in stable deep geological formations for long periods of time (some hundred thousand years), any release of which might take place in the future will pose no significant health or environmental risk. Partitioning and transmutation (P&T) is the one of the most important strategies to reduce the long-term radiotoxicity of HLW[1].

2-40 Influence of Different Oxidation Temperature on Phase Separation Characteristics of (U1..xNdx)3O8 Solid Solutions

Rare-earth (RE) elements in spent nuclear fuel are strong neutron absorbers, which affect the fission efficiencyof fissile materials. If some of these fission products (e.g., RE) can be removed by a thermo-mechanical process, itwill greatly improve the burn-up and economics of the recycled fuel in the DUPIC (Direct Use of spent PWR fuelin CANDU Reactors) concept[1;2]. In this work, the phase separation characteristics of the Nd (3%) element from(U1?xNdx)3O8 by high temperature oxidation was investigated in terms of the heat treatment temperature rangebetween 1 000 ?C and 1 700 ?C. The phase separation ratio (wt%) of Nd and U was evaluated using the XRD. Themorphology of the samples were obtained from SEM.

Separation of Actinium-228 from the old Thorium-232 Reagent

The removal of radioactive actinide from rare earth products is an important task and key technology in the production of rare earth products.That is because element Actinium(Ac)and Lanthanum(La)belong to the same clan in the periodic table.

Spent Nuclear Fuel Reprocessing and Refabrication in IMP

With the development of nuclear power,more and more spent nuclear fuel will be produced and accumulated.Reprocessing of these spent nuclear fuel became the key issues for the environmentally friendly and sustainable development of nuclear energy.

高效选择性分离乏燃料中裂变产物的新技术

We describe herein an environmentally benign strategy for removing of fission products from spent nuclear fuel by the selective dissolution using carboxyl-functionalized ionic liquid[Hbet][Tf2N].Water-statured[Hbet][Tf2N]can dissolve lanthanides oxide from simulated spent nuclear fuel with a dissolution ratio of 100%at 40℃.However,the dissolution of uranium is almost neglect(<1%)under the same conditions.This process of separation displays an outstanding performance to separate some key fission products oxide such as neutron poisons Ln2O3 efficiently and allows the recovery of actinides AnO2 as a group in solid form.

制备与表征压水堆模拟乏燃料芯块的研究

At present,almost all commercial nuclear power plants in China are Pressurized Water Reactors(PWR).It is well-known that uranium dioxide(UO2)ceramic fuel is the basic nuclear fuel for present reactors,especially for PWR.In order to study the morphology of the fission products(FPs)and minor actinides(MAs)in spent fuel,stable elements can be added proportionally to UO2 in the laboratory without intense radioactivity[1].The higher temperature conditions in the reactor should also be simulated for preparing PWR spent fuel pellets.

旋风分离法去除模拟乏燃料中富稀土相的研究

Rare earth(RE)elements have a large neutron cross section so that it should be removed before the reuse of spent fuel for improving the utilization of U resources.The volatilization technology[1]can release most of volatile and semi-volatile fission elements,but not any significant amounts of RE.Based on the previous investigation on high temperature crystallization and the formation of rich and poor RE phase[2,3],the removing RE-rich phase from simulated fuel is studied in this work.As literatures report,the conventional separation techniques include sieving,air classification,sedimentation,and so on.The cyclonic sieving method is the promising appoach at present with the advantages of small equipment,simple operation and high efficiency.

Production and Separation of the Medical Isotopes in IMP

Radioisotopes are widely used for diagnostics,therapy of various diseases,and research in nuclear medicine.But the all medical isotopes used in the hospital of China were bought from overseas.Hence,we need develope the corresponding technologies about the production and separation of the radioisotopes.

2-32 Release and Gathering of Semi-volatile Fission Products(Mo,Te)in the UO2 Simulated Fuel

The volatilization technology,which is used for pulverizing uranium oxide ceramic pellets,decladding,and removal of most of volatile and semi-volatile fission elements from spend fuel,has been developing as main treatment process for ADS nuclear fuel cycle.In the oxidation/reduction steps(400℃to 600℃),most of the volatile nuclides such as Kr,Xe,C-14,H-3,can be removed.However,the higher temperature is needed to release semi-volatile fission products.

2-35 An Solvent Extraction and Complexation Study on Americium(III)and Europium(III)with Tridentate N,N-diethyl-1,10-Phenanthroline-2-Amide

In the spent fuel reprocessing,the high-level liquid waste(HLLW)from PUREX process is the major environmental concern of its high radiotoxicity level[1].The partitioning and transmutation(P&T)strategy,aiming at transforming the minor actinides into short-lived or stable isotopes with neutron bombardment,is one of the most perspective technology to solve this problem.However,the lanthanides in HLLW have very high neutron capture cross-sections,and need to be removed before the transmutation.