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。

加速器直接生产^(99m)Tc的化学分离纯化研究现状

^(99m)Tc(T_(1/2)=6.01 h)是^(99)Mo的衰变子体,是目前核医学临床诊断应用最为广泛的放射性核素,其使用量约占所有诊断放射性同位素的80%。近年来,基于回旋加速器通过核反应^(100)Mo(p,2n)^(99m)Tc直接生产^(99m)Tc已经成为国际上比较认可的方法,具有不需要反应堆、无高浓缩铀、放射性废物少、不存在核扩散风险等优势。本文针对加速器直接生产技术所发展的几种^(99m)Tc化学分离纯化方法进行了详细阐述,包括柱色谱分离、溶剂萃取、化学沉淀以及热色谱法。本工作可为我国开展加速器直接生产^(99m)Tc提供一定的参考。

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。

家庭群组式孕期保健模式对妊娠结局的影响

目的探究家庭群组式孕期保健模式对妊娠结局的影响。方法选取2018年10月—2019年10月在我院建档且规律产检的70例产妇,依据随机数字表法分为对照组和观察组,每组各组35例。对照组给予传统保健,观察组采用家庭群组式孕期保健模式。观察两组孕妇的妊娠结局、母乳喂养情况以及心理状态。结果观察组阴道分娩率、新生儿1 min Apgar评分显著高于对照组,剖宫产率、孕妇产后2 h出血量显著低于对照组,差异有统计学意义(P<0.05)。观察组孕妇产后第1天、第7天、6个月母乳喂养率显著高于对照组,差异有统计学意义(P<0.05)。干预前,两组孕妇SAS评分及SDS评分比较,差异无统计学意义(P>0.05);干预后,两组评分均降低,且观察组显著低于对照组,差异具有统计学意义(P<0.05)。结论家庭群组式孕期保健模式通过整个家庭的参与,使孕妇获得了医务人员、家属、同伴的全面支持,能够有效改善妊娠结局,促进自然分娩,提升母乳喂养率,缓解孕妇的焦虑与抑郁情绪,值得临床推广。

2-26 Gas-phase Chemistry of Short-lived Re Carbonyl Complexes Part 2: Chemical Yields in Gas-phase Reactions

After the volatile Re carbonyl complexes were synthesized and their volatility was studied we performed another experiment to measure their chemical yields when He were used as the carrier gas. The same experimental setups were used except the low temperature isothermal chromatography device[1]. The natGd2O3 target and 23Na7+ion beam were used to produce short-lived Re isotopes, and the Gas-filled Recoil Ion Separator (GARIS) was employed to separate the evaporation residues[2]. High purity He gas and CO gas were used as the mixed gas. The depth of recoil chamber was 100 mm because of the long stop range in He gas, and the gas pressure was around 80 kpa. The total gas flow rate was 1 L/min.

2-25 Gas-phase Chemistry of Short-lived Re Carbonyl Complexes Part 1: Adsorption Enthalpy on Teflon Surface

In the collaboration of RI Applications Team from RIKEN (Japan) and the Nuclear Chemistry Group from IMP (China), the short-lived Re carbonyl complexes were synthesized and investigated. As the lighter homologs of superheavy element Bh, Re belongs to period 6, group 7 of the periodic table. Short-lived Re isotopes with half-lives of several minutes were produced in the reactions of natGd(23Na7+, xn) 172?177Re at Nishina center of RIKEN.

2-18 Seperation of Rare Earth (RE) Elements from Simulated Spent Fuel (SIMFUEL) by Flotation Process

Rare-earth (RE) elements in spent nuclear fuel, which are produced by uranium fission and the decay of other fission products[1] can absorb neutrons effectively[2]. RE elements are the main contributors to the neutron burden of spent nuclear fuel (approximately 50%)[1] , which strongly affect the utilization efficiency of nuclear fuel. In order to greatly improve the economics of the recycled nuclear fuel it is very necessary to separate RE elements from the spent nuclear fuel.

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.

2-36 Simultaneous Determination of U and Nd by Binary Ration and X-ray Fluorescence Spectrometry

X-ray fluorescence spectrometry is a powerful tool for the determination of elements in a wide variety of samplematrices[1]. It is a relatively fast method of analyzing the elemental composition of a sample. Specimens placed inthe instrument can be in the form of either solids or liquids, and the specimen is neither consumed nor destroyedduring the analysis[2]. In the present work, a rapid method for determination of U and Nd in simulative spent fuelby binary ration and X-ray fluorescence spectrometry was developed. The determination of U and Ce in simulativeMOX fuel samples by binary intensity ratio and X-ray fluorescence spectrometry has been studied[3].

2-41 Gas-phase Chemistry of Technetium Carbonyl Complexes

Gas-phase chemical behaviors of short-lived technetium carbonyls were studied by using low temperature isothermalchromatograph (IC) coupled with a 252Cf spontaneous fission (SF) source. Fission products recoiled from the252Cf SF source were thermalized in a CO contained mixed gas, and then technetium carbonyls were formed inreactions of CO gas and various technetium isotopes. A gas-jet system was employed to transport the volatilecarbonyls from a recoil chamber to the IC. Short IC columns made of Fluorinated Ethylene Propylene (FEP) Teflonand quartz were used to obtain the chemical information of technetium carbonyls. The results of 104Tc -106Tc car-bonyls were found to be strongly influenced by theirprecursors, showing the chemical behaviors of 104Mo-106Mo carbonyls, respectively. However, 107Tc and108Tc could represent the chemical information of elementtechnetium, due to their high independent yieldsand very short half-lives of their precursors 107Mo and108Mo.

2-38 Separation of Rare Elements from Spent Nuclear Fuel

Rare-earth (RE) elements (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd and others) are produced in nuclear fuel by uraniumfission and by the decay of other fission products. Rare-earth (RE) elements in spent nuclear fuel are strong neutronabsorbers, which affect the fission efficiency of fissile materials and decrease the thermal conductivity of the UO2matrix. Thus, to enhance the thermal conductivity and nuclear energy production of reused fuel, the separation ofRE elements from spent nuclear fuel is very necessary.

Application of Deep Eutectic Solvents in the Separation of Rare Earth Elements

Deep eutectic solvent(DES)is usually a mixture prepared by the complexation of hydrogen bond acceptor(HBAs)and hydrogen bond donor(HBDs)at mild performance temperature.Similar to ionic liquid,DES has unique physicochemical properties such as low steam,strong conductivity,stable electrochemical window and strong design ability.Under a relatively mild condition,DES still shows a strong dissolving ability for a variety of insoluble substances.

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.

^(99)Mo production via (p, f) Reaction on Natural Uranium

^(99)mTc is the most commonly used diagnostic medical radioisotope because of its short half-life(T1/2=6.01 h)and low β-energy(140.5 keV)[1].Generally,^(99)mTc is obtained from^(99)Mo decays by β-emission.

Highly Efficient and Selective Dissolution Separation of Fission Products by an Ionic Liquid[Hbet][Tf_(2)N]:A New Approach to Spent Nuclear Fuel Recycling

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.

Selective Separation of Neutron Poisons from Spent Nuclear Fuel using a Carboxyl-functionalized Ionic Liquid

Reprocessing of spent nuclear fuel became the key issues for the environmentally friendly and sustainable development of nuclear energy.For the future development of nuclear energy requirements,the concept of an acceleratordriven advanced nuclear energy system(ADANES)has been proposed in China.ADANES consists of a burner system and a fuel recycle system.The waste transmutation,breeding,and power production are implemented in the burner driven by the neutron source outside the accelerator.It is not necessary to carry out the fine partitioning for minor actinides due to the higher-power neutron source.Hence,in this fuel reprocessing,only part of the fission products containing neutron poisons from spent nuclear fuels will be separated and disposed.The rest spent nuclear fuel,uranium dioxide along with transuraniums including Pu,Np and Am will be regenerated as new nuclear fuels and burned subsequently.

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.