Vol.26,

The electrochemical behavior of Pd(II) and Rh(III) in [EMIm]NTf₂ ionic liquid has been studied on Pt working electrodes at 298 K by cyclic voltammetry (CV), polarization curve and galvanostatic transient techniques. Cyclic voltammogram of Pd(II) in [EMIm]NTf₂ consists of two cathodic current peaks located at 1.37 V(E_pc2), corresponding to Pd²⁺/Pd⁺, and at 0.69 V (E_pc1) corresponding to Pd⁺/Pd. The transfer coefficient α was calculated by the Tafel extrapolation from the polarization curves to be 0.306, which is in agreement with the value reported in an aqueous solution system. For Rh(III) in [EMIm]NTf₂, a cathodic current peak (E_pc) was observed at -0.39 V, corresponding to Rh³⁺/Rh, and two oxidation peaks were observed at -0.13 V (E_pa1) and 0.37 V (E_pa2) during the reverse scan. A significantly negative shift in the cathodic peak potential was observed with the increase of the scan rate, indicating that the reduction of Pd(II) and Rh(III) on the Pt electrode involves kinetic complications. By using the galvanostatic transient technique, the diffusion coefficients of Pd(II) and Rh(III) in [EMIm]NTf₂ ionic liquid solution were found to be ∼10^-7 cm²/s. The potential difference between the reduction of Pd(II) to Pd and the reduction of Rh(III) to Rh obtained from the CV curves of the Pd(II) and Rh(III) co-existing [EMIm]NTf₂ solution is found to be about 0.74 V, which makes it possible to electrodeposit Pd(II) and Rh(III) separately.

450

Extraction behavior of lanthanides (La, Eu, Dy, Lu) from HNO₃ solution was studied using a novel extraction system with hydrophobic ionic liquid being diluent and isobutyl-BTP being extractant. Compared with that in isobutyl-BTP/cyclohexane extraction system, application of ionic liquid as the extracting phase provided unprecedented enhancement of the extraction performance of isobutyl-BTP for lanthanides. It was found that the isobutyl-BTP/[C_nmim][NTf₂] extraction system is favorable to get good extraction at low acidity condition (<0.1 M). Of all the isobutyl-BTP/ [C_nmim][NTf₂] (n=2, 6, 8) systems, isobutyl-BTP/[C₂mim][NTf₂] extraction system provides the best extraction performance and fastest extraction kinetics within 5 min towards Dy³⁺. The extraction is spontaneous endothermic and temperature is good for extraction. The transfer of lanthanides, in isobutyl-BTP/[C₂mim][NTf₂] extraction system, proceeded via a cation exchange mechanism, in contrast to extraction of neutral complex in the cyclohexane system.

559

A burnup calculation was performed to analyze the Après ORIENT process, which aims to create highly-valuable elements from fission products separated from spent nuclear fuels. The basic idea is to use nuclear transmutation induced by a neutron capture reaction followed by a β^- decay, thus changing the atomic number Z of a target element in fission products by 1 unit. LWR (PWR) and FBR (MONJU) were considered as the transmutation devices. High rates of creation were obtained in some cases of platinum group metals (⁴⁴Ru by FBR, ⁴⁶Pd by LWR) and rare earth (⁶⁴Gd by LWR, ⁶⁶Dy by FBR). Therefore, systems based on LWR and FBR have their own advantages depending on target elements. Furthermore, it was found that creation rates of even Z’ (=Z+1) elements from odd Z ones were higher than the opposite cases. This creation rate of an element was interpreted in terms of "average 1-group neutron capture cross section of the corresponding target element ⟨_cZ⟩" defined in this work. General trends of the creation rate of an even (odd) Z’ element from the corresponding odd (even) Z one were found to be proportional to the 0.78th (0.63th) power of ⟨_cZ⟩, however with noticeable dispersion. The difference in the powers in the above analysis was explained by the difference in the number of stable isotopes caused by the even-odd effect of Z.

556

The chlorination of rare earth oxides by MgCl₂ was investigated in the molten chlorides. To reduce the solvent salt volatility, the LiCl-NaCl mixture was selected as a solvent by comparing the mass loss of the LiCl-NaCl with LiCl-KCl melts after the addition of MgCl₂ in the temperature range of 873 K to 1073 K. The dissolution behavior of La₂O₃ was investigated in the LiCl-NaCl-MgCl₂ melts by XRD measurements and ICP-AES analysis of the melts, which indicated that La₂O₃ was chlorinated by MgCl₂ to produce LaCl₃. The reduction peak of La(III) in the LiCl-NaCl-MgCl₂-La₂O₃ melts was observed from cyclic voltammogram and square wave voltammogram. The Mg-La alloy obtained by galvanostatic electrolysis in the LiCl-NaCl-MgCl₂-La₂O₃ melts was characterized by XRD and SEM-EDS, indicating that the Mg-La alloy consisted of Mg and La₂Mg₁₇ phases.

600

The reduction of Tm(III) on a liquid Zn electrode was investigated in a LiCl-KCl melt via cyclic voltammetry, square wave voltammetry, and open circuit chronopotentiometry. On a liquid Zn electrode, the reduction mechanism of Tm(III) ions is through one step with the exchange of three electrons via the formation of a Zn-Tm alloy. This differs from that on an inert electrode, as the reduction is Tm(III) ions were though two consecutive steps. Galvanostatic electrolysis was carried out at a liquid Zn electrode at different current densities in a LiCl-KCl-TmCl₃ melt. The Tm₂Zn₁₇ intermetallic compound was identified in the deposit, except in the Zn phase, by X-ray Diffraction (XRD).

546

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.

502

A new anion exchanger with pyridine groups was prepared by grafting of 2-vinyl pyridine onto polypropylene (PP) nonwoven fabrics by pre-irradiation grafting technique, followed by quaternization of pyridine rings in grafted chains in reaction with bromoethane. The results showed that the grafting yield increased with the monomer concentration and conversion ratio of quaternization increased with the time. The grafted and quaternized fabrics were characterized by FT-IR, DSC, SEM and ICP. The possibility of adsorption of perrhenate (ReO₄^-), a nonradioactive analogue to pertechnetate (⁹⁹TcO₄^-), from aqueous solution by anion exchanger was investigated. The experiments performed at pH= 0.1–6 showed that pH=2.2 was the optimal acidity for ReO₄^- adsorption, and an adsorption equilibrium was achieved in 30 min. The reaction enthalpy was -12.55 kJ/mol, indicating that the adsorption process is exothermic. XPS tests indicated that the ReO₄^- uptake was a typical ion exchange between Cl^- on anion exchanger and ReO₄^-.

657

The reduction of Tc(VII) by methyl-hydrazine(MMH) in HNO₃ aqueous solution was studied under different conditions. A logistic equation widely used for modeling autocatalytic reaction was adopted to simulate the target reaction. All the experimental data were consistent with the proposed equation. Results showed that Tc(VII) was reduced by MMH in two ways, the stepwise reduced by MMH and the autocatalytic reduced by Tc(IV). Isothermal experiments were done at temperatures ranging from 40 ℃ to 55 ℃ and the activation energy were obtained to be 31.51 kJ/mol and 65.68 kJ/mol for the stepwise reduction and autocatalytic reduction, respectively.

456

In light of the problem of radiolysis of the solvent system in PUREX (plutonium uranium recovery by extraction) process, γ and α irradiation stabilities of tributylphosphate (TBP)/n-dodecane/nitric acid system were studied using ⁶⁰Co γ-rays and α particles from ²³⁸Pu. The main degradation products, dibutyl phosphate (HDBP) and monobutyl phosphate (H₂MBP) were detected by the gas chromatography-mass spectrometry (GC-MS), and the degradation products that could not be easily removed by the washing procedure were measured by the Pu retention. Effects of the absorbed dose, the HNO₃ concentration, and the cumulative dose on the irradiation stability of the systems were investigated. The yields of HDBP, H₂MBP and the Pu retention increased with the absorbed dose. The HNO₃ concentration affected significantly on the yield of HDBP, but had little impact on the output of H₂MBP and Pu retention. For a similar absorbed dose, the Pu retention of the solvent by alpha irradiation is larger than that by gamma irradiation.

537

The adsorption behavior of ²⁴¹Am(III) and Eu(III) by silica/polymer-based isoHex-BTP adsorbent (isoHex-BTP/SiO₂-P) was investigated by a batch experiment method. isoHex-BTP/SiO₂-P exhibited high affinity and selectivity for ²⁴¹Am(III) over ¹⁵²Eu(III) in 2–4 mol/dm³ nitric acid solutions. Within the experimental contact time range of 0.5–24 h, isoHex-BTP/SiO₂-P showed high selectivity for ²⁴¹Am(III) compared to ¹⁵²Eu(III) in 3 mol/dm³ nitric acid solution. However, the adsorption kinetics of ²⁴¹Am(III) and ¹⁵²Eu(III) was slow. Eu(III) adsorption followed the pseudo-second-order kinetic model, indicating chemical adsorption as the rate-limiting step of the adsorption process. And the adsorption agreed well with the Langmuir adsorption model at various temperatures. The adsorption kinetics and isotherm data indicated that the equilibrium adsorption capacity, the adsorption rate, the maximum adsorption capacity and the adsorption affinity, increased with temperature. The thermodynamic parameters, negative change in Gibbs free energy, and positive change in enthalpy and entropy, suggested that the adsorption of Eu(III) was spontaneous and endothermic process with an increase of entropy.

461

The water-soluble radiolytic products of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ionic liquid ([C₂mim][NTf₂]) under γ-radiation, such as CF₃SOOH, CF₃SO₂NH₂, HF, and H₂SO₃, were identified by using ¹H NMR, ¹⁹F NMR, and ion chromatography. The extraction behavior of Dy³⁺ using irradiated [C₂mim][NTf₂] in combination with 2,6-di(5,6-diisobutyl-1,2,4-triazin-3-yl)pyridine (isobutyl-BTP) was studied and the abnormal increase of Dy³⁺ partitioning after irradiation is mainly attributed to the precipitation formed between Dy³⁺ and radiolytic products of [C₂mim][NTf₂] (F^- and SO₃^2-). Washing irradiated [C₂mim][NTf₂] with water provides a simple method for ionic liquid recycling.

450

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, _acc, 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^-12 m²/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 _acc 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.

784

The influence of acetate on U(VI) sorption on silica from aqueous solutions was studied at pH 2–7 by complementary experimental methods of macroscopic measurement, spectroscopic investigation and thermodynamic calculation. Sorption percentage of U(VI) in the absence and in the presence of different acetate concentrations was determined by batch sorption procedures. Attenuated total reflection Fourier transform infra-red spectroscopy (ATR-FTIR) was used to elucidate the mechanisms of uranyl sorption on silica in the presence of acetate, by investigating, in-situ, the changes in the U(VI) sorption on silica surface in presence of ligand: the absorption bands of carboxylate ν(COO) in the range 1300–1700 cm^-1 and those around 850–950 cm^-1 of uranyl species _as(UO₂) are followed. The decrease of U(VI) sorption with increasing acetate concentration was observed. Sorption of U(VI)-acetate (U-Ac) species on silica surface was demonstrated for the first time. ATR-FTIR investigations clearly evidenced the absorption bands characteristic of sorbed U-Ac complexes both from the acetate and uranyl spectral regions those the wavenumbers correspond to sorbed species. No sequence effect of acetate and uranyl on the sorption on silica in ternary systems U(VI)-acetate-silica was observed from the sorption data. From the ATR-FTIR investigations, we can induce that the sorption of U-Ac leads to chemical equilibria and makes possible the modeling of sorption isotherms by surface complexation models. The related thermodynamic constants were modeled using CCM surface complexation modeling.

564

Hydriding properties of uranium alloys have been studied to search for new hydrogen storage materials to be applied to hydrogen energy systems. Application of uranium-base hydrogen storage materials can be expected to alleviate the risk, as well as to reduce the cost incurred by globally-stored large amounts of depleted uranium left after uranium enrichment. Various uranium alloys have been examined in terms of hydrogen absorption-desorption properties, among which UNiAl intermetallic compound showed promising characteristics, such as lower absorption-desorption temperatures and better anti-powdering strength. First principle calculation has been carried out on UNiAl hydride to predict the change of crystal structure and the lattice constant with increasing hydrogen content, which showed this calculation to be promising in predicting candidates for good hydrogen absorbers.

522

The soft X-ray interference lithography (XIL) branch beamline at Shanghai Synchrotron Radiation Facility (SSRF) is briefly introduced in this article. It is designed for obtaining 1D (line/space) and 2D (dot/hole) periodic nanostructures by using two or more coherent extreme ultraviolet (EUV) beams from an undulator source. A transmission-diffraction-grating type of interferometer is used at the end station. Initial results reveal high performance of the beamline, with 50 nm half-pitch 1D and 2D patterns from a single exposure area of 400 μm×400 μm. XIL is used in a growing number of areas, such as EUV resist test, surface enhanced Raman scattering (SERS) and color filter plasmonic devices. By using highly coherent EUV beam, broadband coherent diffractive imaging can be performed on the XIL beamline. Well reconstructed pinhole of ϕ20 μm has been realized.

590

The macromolecular crystallography beamline BL17U1 at the Shanghai Synchrotron Radiation Facility (SSRF) is the first dedicated macromolecular crystallography (MX) beamline at a third-generation synchrotron in China. It utilizes an in-vacuum undulator as a source and is energy-tunable from 5 to 18 keV. The beamline was commissioned and opened for users in April 2009. The experimental station was upgraded in 2011 with an advanced detector, a high precision goniometer and an automatic sample exchanger for high efficient and high-throughput data collection of protein crystals. The current set-up allows for remote operation of sample mounting, centering and data collection of pre-frozen crystals. In recent two years, the number of PDB depositions from this beamline exceeds 330 each year. In this paper, we describe the complete BL17U1 beamline with upgraded end station and how it is managed for user community.

460

542

An ion beam analysis system was established on a 1.7 MV tandem accelerator, enabling Rutherford backscattering (RBS), elastic recoil detection (ERD), nuclear reaction analysis (NRA) and channeling measurements. The system was tested by performing qualitative and quantitative analysis of Si, Ni/Si, BiFeO₃:La/Si, MoC/Mo/Si and TiBN/Si samples. RBS of a BiFeO₃:La film was used as system calibration. Tested by ion beam channeling, a Si(100) is of good crystallinity (χ_min = 3.01%). For thin film samples, the measured thickness agrees well with simulation results by SIMNRA. In particular, composition of a MoC/Mo/Si and TiBN film samples were analyzed by RBS and non-Rutherford elastic backscattering.

519

Among different heavy liquid metals (HLMs), lead-bismuth eutectic (LBE) is considered at present as a potential candidate for the coolant of new generation fast reactors (critical and subcritical) and for liquid spallation neutron sources and accelerator driven systems (ADS). A high temperature liquid LBE loop, KYLIN-II-M, has been built to study the characteristics of corrosion and fluidity of LBE at the Institute of Nuclear Energy Safety Technology. However, due to the sensors and execution components of the loop work at high temperatures and in severely corrosive environments, the reliability and security of the data acquisition and control system (DACS) of KYLIN-II-M face challenges during the loop operation. In order to meet the urgent needs for KYLIN-II-M’s long-term stable operation, a virtualization and redundancy control system has been developed. The onsite operation result shows that the DACS is stable and reliable. In this paper, the experimental results are described in detail.

877

Nuclear pulse signal needs to be transformed to a suitable pulse shape to remove noise and improve energy resolution of a nuclear spectrometry system. In this paper, a new digital Gaussian shaping method is proposed. According to Sallen-Key analog Gaussian shaping filter circuits, the system function of Sallen-Key analog Gaussian shaping filter is deduced on the basis of Kirchhoff laws. The system function of the digital Gaussian shaping filter based on bilinear transformation is deduced too. The expression of unit impulse response of the digital Gaussian shaping filter is obtained by inverse z-transform. The response of digital Gaussian shaping filter is deduced from convolution sum of the unit impulse response and the digital nuclear pulse signal. The simulation and experimental results show that the digital nuclear pulse has been transformed to a pulse with a pseudo-Gaussian, which confirms the feasibility of the new digital Gaussian pulse shaping algorithm based on bilinear transformation.

607

The characteristic gamma-ray spectrum of TNT in the soil induced by DT neutrons is measured by the PFTNA demining system. The GEANT4 toolkit is used to simulate the whole experimental procedure. The simulated spectra are compared with the experimental spectra, and they are mainly consistent. The share of the background sources such as neutrons and gamma is obtained and the contribution that the experimental apparatus to the background, such as shielding, detector sleeve and moderator, is analyzed. The effective gamma signal (from soil and TNT) is 29% of the full spectrum signal, and the background signal, more than 68%, this is mainly produced by shielding and the detector sleeve. By gradually optimizing the shielding and the cadmium sheet of the detector sleeve, the share of the effective gamma signal increases to 47%, and the background signal reduces to 18%.

468

Optimization of the inverse planning becomes critical because it follows the invention of intensity modulated radiotherapy (IMRT) to shorten the previous "trial-and-error" treatment process and increase efficiency. In this paper, the inverse planning is used to direct aperture optimization in the ARTS (Accurate/Advanced Radiotherapy System). The objective function was quadratic, both tolerance and dose-volume constraint types are supported. The memory efficient conjugate gradient algorithm is used to cope with its large data. Furthermore, to fully exploit the solution space, a shortest path sub-procedure is coupled into the whole algorithm, thus giving further possibility decreasing the objective function. Two clinical cases are tested, indicating that the applicability of this algorithm is promising to clinical usage.

763

A permanent magnet BLDC (brushless direct current) motor is used to move the control rod of a miniature neutron source reactor (MNSR). The BLDC motor drive is modeled using MATLAB/SIMULINK. Two main parts of the modeling are the inverter switching and the current control. Current control with chopping used to minimize the torque ripple of the MNSR control rod drive. Fuzzy logic current control together with soft chopping control shows the best response of all the three strategies. The prototype drive mechanism has an ATmega32 controller and power MOSFET switches. The simulation results are compared with experimental drive mechanism.

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