Effect of humic acid contact time on the diffusion of Re(Ⅶ) in GMZ bentonite

The effect of humic acid(HA) on the diffusion of Re(Ⅶ) was investigated in compacted Gaomiaozi(GMZ)bentonite by the through- and out- diffusion method. The effective diffusion coefficient, D e, and accessible porosity, εacc, were measured in order to evaluate the impact of humic acid on Re(Ⅶ) diffusion. The D e value was in the range of(5.2–8.3)×10-12m2/s. The diffusion of Re(Ⅶ) was enhanced in the presence of HA, and the D e value increased with the increase of ageing time, indicating that the formation of HA-Re complexes was slow. Moreover, the εacc was in the range of(0.06– 0.16), which is less than the total porosity. It implies that the HA-Re complexes are anions.     

Calculation and Analysis of Neutron Induced Reaction on ~(185,187)Re and ~(Nat)Re

Based on the relevant experimental data of Re and neighbor nucleus W, and the theoretical model calculations, neutron induced reaction cross sections, the energy spectrum, angular distribution, double differential cross section and γ-production data were calculated for ~(185,187,Nat)Re at incident neutron energies below 20 MeV. The calculated results were compared with experimental data.     

Adsorption of Th(Ⅳ) and Ce(Ⅳ) on Zirconium Based Metal-organic Framework Zr-CAU-24

In this paper, zirconium based metal-organic frameworks (MOFs) Zr-CAU-24 was successfully prepared by using solvothermal method, which was one kind of zirconium based MOFs. Zr-CAU-24 has nanoporous structure with BET specific surface area of 1 610 m²/g. Thermogravimetric analysis (TGA) and irradiation stability test were conducted. Taking Zr-CAU-24 as adsorbent, the adsorption characteristics of Th(Ⅳ) and Ce(Ⅳ) on Zr-CAU-24 were investigated through static adsorption experiments. The effects of contact time, initial pH on Th(Ⅳ) and Ce(Ⅳ) adsorption by Zr-CAU-24 were investigated respectively, and the kinetics and thermodynamics were investigated. The results indicate that Zr-CAU-24 has good thermal stability and irradiation stability. The quasi-second-order model provides a good explanation for the adsorption process of Th(Ⅳ) and Ce(Ⅳ) on Zr-CAU-24, which is a chemical adsorption process. The active site of Zr-CAU-24 is evenly distributed, and the adsorption is a single layer adsorption. Through the study of selective adsorption of mixed metal ions on Zr-CAU-24, it is found that Zr-CAU-24 has the adsorption selectivity for Th(Ⅳ) and Ce(Ⅳ).     

Influence of Technetium on Stability of U(Ⅳ) and Hydrazine in 1B Unit of Purex Process

<正>In this research,the technetium-catalyzed oxidation of U(Ⅳ)-hydrazine by nitric acid was studied by spectrophotometry.The results show that to the catalyzed oxidation reaction rate of U(Ⅳ),the concentration of technetium and temperature were the major influence factors,the concentration of U(Ⅳ)shows first order reaction characteristics,the concentration of hydrazine has only a little influence.In the nitric acid solu-     

Electrolytic reduction of Re(Ⅶ) using a flow type electrolysis cell and its possibility of radiopharmaceuticals application

The electrochemical properties of perrhenate were studied in hydrochloric acid solution via cyclic voltammetry by disk glassy carbon electrode. The electroreduction of perrhenate was performed at a constant potential-0.33 V(vs. Ag/AgCl) with a potentiostat by a flow type electrolysis cell. It was found that the change of rhenium ion concentration before and after electrolysis was negligible. This means almost no rhenium or rhenium oxides were deposited on the carbon fiber electrode during the electroreduction. The rhenium ion solution changed from colorless into yellow-brown after electrolysis process. UV-Visible spectrophotometry was used to characterize the oxidation states of Re before and after electrolysis. Some obvious peaks were detected after electrolysis, indicating that Re(Ⅶ) was reduced to Re(V). The complex behavior and stability of Re(V)-HEDP were discussed for the purpose of electroreduction of Re(Ⅶ) or Tc(Ⅶ) on radiopharmaceuticals production.     

Preparation and properties of ~(117m)Sn(Ⅳ)-TTHMP in in-vitro and in small animals

In this work,TTHMP was synthesized and labelled with ~(117m)Sn.The preparation conditions,stability and lipophilicity of ~(117m)Sn(Ⅳ)-TTHMP were investigated.Biodistribution of the complex in rabbits and mice was studied. It was found that the quantity of TTHMP and pH value of the preparation solution had vital effects on the labeling yield of ~(117m)Sn(Ⅳ)-TTHMP.It was also found that ~(117)Sn(Ⅳ)-TTHMP was hydrophilic and stable at room tempera- ture and 37℃in open air.~(117m)Sn(Ⅳ)-TTHMP showed unexpectedly high bone uptake and bone-to-blood ratio in the animals.This made it potentially useful as an reagent for skeletal scintigraphy and radiotherapy of bone tumors.     

Reaction of N,N-Dimethylhydroxylamine and Tc(Ⅶ) in Nitric Acid Medium

N,N-dimethylhydroxylamine (DMHAN) is the reductant used in the Purex process study. The reaction of Tc(Ⅶ) and DMHAN in nitric acid medium was researched by extraction method under     

Biological reduction and intracellular trapping differences of ^188Re（Ⅶ） and ^99Tc^m（Ⅶ） in Escherichia coli

99Tcm is the most commonly used diagnostic radioisotope.And 188Re is an excellent therapeutic radioisotope with a gamma photon for imaging.Both locate in the same group and have very similar properties.99Tcm(Ⅶ) can be partially reduced to a black insoluble precipitate by aerobic cultures of Escherichia coli,and trapped intracellularly.However,188Re(Ⅶ) cannot be reduced and trapped,because of its lower oxidizing power of perrbenate as compared with pertechnetate or other reasons.     

Effect of ~(103)Pd on proliferation and apoptosis of vascular smoothmuscle cells

This study aimed at the effect of γ-emitting radionuclide l03Pd on the proliferation and apoptosis of vascular SMCs (smooth muscle cells) in vitro. The cavy aortic SMCs were cultured with culture medium M-199. The experiments were carried out in two groups, one for proliferation test and the other for apoptosis test. In each group, 103Pd solutions with various radioactivities were respectively added to the culture solution to irradiate SMCs for 72 h, while non-radioactive palladium solution was added to the control. H-thymidine incorporation test and liquid scin-tillator were used to detect the effect of 103Pd on the proliferation of SMCs. Flow cytometer was used to detect the apoptotic SMCs. The inhibition rate of SMCs proliferation by 1.85 MBq 103Pd solution was 2.3%, which was not significant, while the inhibition rate increased from 41.6% to 91.3% as the 103Pd activity increased from 7.40 MBq to 37 MBq. The apoptosis rate of SMCs was extremely low (less than 4.0%) by 103Pd with activity from 1.85 M     

Measurement of 76Se and 78Se (γ, n) Cross Sections

The (γ, n) cross sections of Se isotopes (⁷⁶Se,⁷⁸Se) were measured to supply fundamental data for estimating the inverse reaction cross section, i.e., the ⁷⁹Se(n, γ)⁸⁰Se cross section. The enriched samples and a reference ¹⁹⁷Au sample were irradiated with laser-Compton scattering (LCS) γ-rays. The excitation function of each (γ, n) cross section was determined for the energy range from each near neutron separation energy to the threshold energy of (γ, 2n) reaction. The energy point corresponding to each cross section was deduced using the accurately determined energy distribution of LCS γ-rays. Systematic (γ, n) cross sections for Se isotopes including ⁸⁰Se were compared with those calculated by using a statistical model calculation code TALYS.     

Study on Mechanism of Third Phase Formation in Extraction of Zirconium(Ⅳ) by TBP in n-dodecane

<正>Formation of third phase in Purex process has been investigated under various conditions,because it may limit the concentration of plutonium (]Ⅳ) in Purex process,and may affect the normal operation of the process.Because of the specialty of plutonium,an analogue,Zr(]Ⅳ) was used to study the third phase formation in this research,which will provide the basic data for third phase formation of plutonium.     

Re(Ⅶ)在辐照膨润土中的扩散行为研究

高庙子(GMZ)膨润土在长期深地质处置过程中会受到高放废物的辐照,物理化学性质可能会发生改变。本文采用贯穿扩散实验法,研究了pH=3.0和10.0条件下,Re(Ⅶ)在1MGy辐照的蒙脱石和膨润土中的扩散行为,并与未辐照的蒙脱石和膨润土相比较,得到了有效扩散系数De和有效孔隙率εacc。结果表明:pH=3.0时,De=(1.00~1.49)×10~(-11) m~2/s,εacc=0.09~0.14;pH=10.0时,De=(1.50~2.10)×10~(-11) m~2/s,εacc=0.07~0.11。随着酸度的增加,有效扩散系数和孔隙率基本不变,说明pH值对Re(Ⅶ)的扩散过程无影响。在蒙脱石中,辐照后的有效扩散系数降低;而在膨润土中,辐照后的有效扩散系数升高,这可能是由于γ辐照改变了膨润土除蒙脱石以外黏土的微观结构,有效孔隙率的增加导致Re(Ⅶ)扩散通道的宽度增加。但由于有效扩散系数和有效孔隙率的改变不大,γ辐照对Re(Ⅶ)的表观扩散系数的影响不明显。此外,De与εacc的关系可通过Archie定律表述,胶结因子n=1.7~2.4。     

PUREX流程中Tc(Ⅶ)对U(Ⅳ)反萃Pu(Ⅳ)的影响

研究了Tc()对U()还原反萃Pu()的影响。研究结果表明,在单级反萃中,有机相中锝的初始质量浓度高达441mgL时,Pu()的反萃率无明显改变;两相混合放置时间足够长时,Pu()的反萃率会降低,而且开始降低的时间随锝浓度增加而缩短;体系中有机相和水相的酸浓度、Pu浓度、U()及U()浓度的变化在所研究的范围内对Pu()反萃率的影响都不大。逆流萃取的串级实验结果表明,当1BF中Tc()的质量浓度大于135mgL时,会严重影响Pu()的反萃;小于70mgL时,对Pu()的反萃无明显影响。研究还表明,引起Pu()反萃率降低的原因是肼在低价锝的催化作用下的破坏。降低Tc()含量和缩短放置时间都有助于减小PUREX流程中锝对U()反萃Pu()的影响。     

Solubility Study on Tc(Ⅳ) in the Underground Water

The solubility of Tc(Ⅳ) in BS03 well underground water( from the Beishan region, Gansu province, which is being investigated as a potential candidate high-level radioactive waste disposal site)has been measured with the variation of pH(6～10), storage ti…     

Re(Ⅶ)在塔木素黏土中的扩散行为

为确定阴离子在塔木素黏土中的扩散规律,本文采用毛细管法测定Re(Ⅶ)(模拟⁹⁹Tc(Ⅶ))在塔木素黏土中的扩散行为。首先,对辐照前后黏土的化学组分、比表面积、孔径和有机物含量进行了表征分析。其次,对压实密度、离子强度和酸度对Re(Ⅶ)在辐照前后塔木素黏土中扩散行为的影响进行了实验研究。结果表明,Re(Ⅶ)在辐照前后塔木素黏土中的扩散系数量级为10^-10 m/s。表观/有效扩散系数均随压实密度的增大而减小,有效扩散系数与孔隙率符合Archie定律,胶结因子分别为0.8和2.1。Re(Ⅶ)的表观/有效扩散系数随离子强度的增大而增大,这是因为离子强度增大,导致孔径增大,扩散加快。但Re(Ⅶ)在不同酸度下的扩散系数基本不变。此外,辐照使Re(Ⅶ)的扩散速度减小,这是因为辐照对黏土比表面积、孔径和有机物含量的影响造成的。     

Reaction Between Mono-methylhydrazine and Tc(Ⅶ) in Nitric Acid Medium

Methyl hydrazine (MMH) is a supporting reagent used in the Purex process in order to eliminate nitrous acid in the system. The reaction between MMH and Tc(Ⅶ) in nitric acid medium was studied by extraction method. The influences of temperature, acidity, the concentrations of MMH and pertechnetate     

Study on Extraction of Pu(Ⅳ) by Tri-iso-Amyl Phosphate

The extraction performance of Pu(Ⅳ) with tri-iso-amyl phosphate (TiAP) were studied. The effects of the concentration of nitric acid and the ratio of phase on the extraction efficiency of Pu(Ⅳ), and on the     

Tc(Ⅶ)与Re(Ⅶ)在TEVA及AG1-X4树脂上的化学行为相似性

样品中⁹⁹Tc的测定需经过预处理及化学分离纯化等过程，由于流程复杂，往往存在锝的损失，因此选择合适的示踪剂是准确测定锝含量的关键。本工作采用静态法与柱实验相结合，分别研究了固相萃取树脂TEVA及离子交换树脂AG1-X4对样品中⁹⁹Tc的分离纯化条件，探究了Re和Tc在化学分离纯化过程中的行为相似性。结果表明：TEVA及AG1-X4树脂对ReO^-₄和TcO^-₄都有着较强的吸附能力，选择pH为9～11范围上柱，采用高浓度HNO₃洗脱，Re和Tc的化学行为基本一致，且回收率均在90%以上。通过控制实验条件，可利用Re作为Tc的稳定非同位素化学类似物获取⁹⁹Tc在分析流程中的化学回收率。     

Adsorption of Th(Ⅳ) and Ce(Ⅳ) with Zirconium Based Metal-organic Framework Zr-CAU-24

<正>Zirconium based metal framework (Zr-CAU-24) is a kind of newly discovered MOFs with small pore size and stable structure,the crystal of Zr-CAU-24 contains two kinds of cage structures,octaheron and tetrahedron.The diameter of the cage is 5.3×10.5 A and 2.4×3.5 A,respectively.A mixture of H4 TCPB (1,2,4,5-tetrakis C 4-car boxyphenyl) benzene,98%) and zirconium(Ⅳ) dinitrate oxide hydrate (98%,