Results of full scale CONSTOR® V/TC prototype 9 m horizontal drop test

Abstract

In the context of the research on the mechanical safety of packages for radioactive material, full scale drop tests with spent fuel and high activity waste transport and storage casks have been performed by the Federal Institute for Materials Research and Testing (BAM). The research reflects national and international interest in acquiring comparative knowledge of full and reduced scale model drop tests as well as in finite element calculations. This paper presents the experimental, analytical and first numerical results of the full scale drop test with the full scale CONSTOR^® V/TC prototype, manufactured by GNS, Gesellschaft für Nuklear-Service mbH, Germany. The prototype was tested by BAM in a 9 m horizontal drop test onto the unyielding target of the BAM drop test facility in Horstwalde, Germany.     

A steam generator model identification and robust H∞ controller design with ν-gap metric for a feedwater control system

A robust H_∞ controller for the feedwater system of KSNP (Korean Standard Nuclear Power Plant) vertical U-tube type steam generators (UTSG) is presented herein. As the first step of the controller development, a precise thermal–hydraulic model for the steam generator is built. A series of model experiments are performed using the developed thermal–hydraulic model in order to acquire the input–output data sets which represent steam generator characteristics. These data sets are utilized to build simplified steam generator models for control through a system identification algorithm, Simple Process Models. Among the developed steam generator models, the representative models for the designated power ranges are selected by a criterion of ν-gap metric. The representative robust controllers for the selected models are designed utilizing the loop-shaping H_∞ design technique. Finally, the robustness and performance of the proposed controllers are validated and compared against those of PI (proportional–integral) controller. The validation results demonstrated that the proposed H_∞ robust controller has a superior robustness and an enhanced control performance.     

Modifications to COBRA-TF to model dispersed flow film boiling with two flow,four field Eulerian–Eulerian approach – Part 2

In the first part of the paper, the modifications performed to improve the dispersed flow film boiling model in COBRA-TF have been described. The improvements were achieved by adding a small droplet field to the code’s solution scheme. The conservation equations, the source terms for the equations and the models developed were summarized. In this paper, the effects of spacer grids on the dispersed flow heat transfer and COBRA-TF modifications for the spacer grid models are presented. The results of the code predictions are presented by comparing the experimental data from Rod Bundle Heat Transfer experiments with the results of code simulations performed with original and modified code. Measurements and calculations for the spacer grid temperature have been compared. The results of the analysis performed with the modified code indicate the improvement in code predictions for the spacer grid temperature.     

DBD coupled with MnOx/γ-Al2O3 catalysts for the degradation of chlorobenzene

This paper investigates the degradation of chlorobenzene by dielectric barrier discharge(DBD)coupled with MnOx/γ-Al2O3 catalysts.MnOx/γ-Al2O3 catalysts were prepared using the impregnation method and were characterized in detail by N2 adsorption/desorption,x-ray diffraction and x-ray photoelectron spectroscopy.Compared with the single DBD reactor,the coupled reactor has a better performance on the removal rate of chlorobenzene,the selectivity of COx,and the inhibition of ozone production,especially at low discharge voltages.The degradation rate of chlorobenzene and selectivity of COx can reach 96.3%and 53.0%,respectively,at the specific energy density of 1350 J l-1.Moreover,the ozone concentration produced by the discharge is significantly reduced because the MnOx/Al2O3 catalysts contribute to the decomposition of ozone to form oxygen atoms for the oxidation of chlorobenzene.In addition,based on analysis of the byproducts,the decomposition mechanism of chlorobenzene in the coupled reactor is also discussed.     

Yield of H2O2in Gas-Liquid Phase with Pulsed DBD简

Electric discharge in water can generate a large number of oxidants such as ozone, hydrogen peroxide and hydroxyl radicals. In this paper, a non-thermal plasma processing system was established by means of pulsed dielectric barrier discharge in gas-liquid phase. The electrodes of discharge reactor were staggered. The yield of H2O2 was enhanced after discharge. The effects of discharge time, discharge voltage, frequency, initial pH value, and feed gas were investigated. The concentration of hydrogen peroxide and ozone was measured after discharge. The experimental results were fully analyzed. The chemical reaction equations in water were given as much as possible. At last, the water containing Rhodamine B was tested in this system. The degradation rate came to 94.22% in 30 min.     

The Influence of Triaxiality Parameter γ on the Chiral Doublet Bands with (πg9/2)～（-1）(νh11/2)～2 Configuration

The chiral doublet bands with three-quasiparticle configuration (πg 9/2) 1 (νh 11/2) 2 are studied by the fully quantal triaxial particle rotor model.The energy spectra and B(M1)/B(E2) ratios of the doublet bands with different triaxiality parameter γ are systemati-cally analyzed.It is found that γ is a sensitive parameter for the properties of these doublet bands.     

Thermoluminescence properties of isostructural K2YF5 and K2GdF5 crystals doped with Tb in response to α, β and X-ray irradiation

The thermoluminescence (TL) properties of isostructural fluoride K₂YF₅ and K₂GdF₅ crystals doped with Tb³⁺ of different concentrations have been studied in the temperature range from 30 to 500 °C after α, β and X-ray irradiation. Strongly different structures of TL glow curves following α or β irradiation have been found for Tb³⁺ doped K₂YF₅ for all studied concentrations of Tb³⁺ whereas for K₂GdF₅ crystals the different TL curves after α or β irradiation are detected only for heavily doped samples. On the other hand, all the studied materials show similar TL glow curves after β or X-ray irradiation. It has been discovered that K₂YF₅ doped with 1 at.% Tb³⁺ has TL radiation sensitivity to β irradiation of the same order as that of the well known TLD-100 (LiF:Mg,Ti) phosphor and much higher sensitivity to α irradiation. The TL mechanism in K₂YF₅ and K₂GdF₅ doped with Tb³⁺ is discussed by taking into account the TL emission spectra from irradiated samples, which are identical to the emission spectra of the Tb³⁺ ions in these hosts under photo-excitation, and the kinetics parameters obtained with the method of various heating rates.     

Destruction of H2S Gas with a Combined Plasma Photolysis（CPP） Reactor

A combined plasma photolysis(CPP) reactor that utilized the dielectric barrier discharge(DBD) plasma together with DBD-driven KrI excimer ultraviolet emission was applied to the decomposition of H 2 S gas.The effects of applied voltage,input current,gas flow velocity,original concentration as well as the ratio of Kr/I 2 mixture on H 2 S removal efficiency were investigated.Gas streams containing H 2 S were separately treated with single DBD and CPP reactor under the same conditions.In comparison to DBD,CPP could greatly enhance the H 2 S removal efficiency at the same applied voltage,inlet gas concentration and gas flow velocity.In addition,the reaction mechanism was also discussed in this paper.     

Electroluminescence from metal-oxide-silicon tunneling diode with ion-beam-synthesized β-FeSi2 precipitates embedded in the active region

A metal-oxide-silicon (MOS) tunneling light-emitting diode is fabricated with ion-beam-synthesized β-FeSi₂ precipitates embedded in the active region. Fe ions were implanted into p⁻-100 silicon substrate at cryogenic temperature (∼−120 °C), followed by rapid thermal oxidation (RTO). Under constant voltage biased in accumulation and at temperatures down to 80 K, electroluminescence (EL) with wavelength peaking at ∼1.5 μm is observed at a current density of about 2.0 A/cm². Light output increases linearly with current density. Temperature dependence of the EL shows that the luminescence is due to interband recombination in the crystalline precipitates. The strain in these isolated precipitates may contribute to the luminescence properties of β-FeSi₂ in silicon.     

Can redox sensitive radionuclides be immobilized on the surface of spent nuclear fuel? - A model study on the reduction of Se(IV)aq on Pd-doped UO2 under H2 atmosphere

Spent nuclear fuel contains noble metal particles composed of fission products (Pd, Mo, Ru, Tc, Rh and Te, often referred to as ε-particles). Studies have shown that these particles play a major role in catalyzing oxidative dissolution as well as H₂ reduction of the oxidized UO₂ fuel matrix, depending on the conditions. Thus it is possible that these particles also could have a major impact on the state of other redox sensitive radionuclides (such as the long lived fission product ⁷⁹Se) present in spent nuclear fuel. In this study, Pd-doped UO₂ pellets are used to simulate noble metal particles inclusions in spent nuclear fuel and the effect on dissolved selenium in the form of selenite (250 μM selenite) in simulated ground water solution (10 mM NaCl, 10 mM NaHCO₃) at 1 and 10 bar hydrogen pressure. The selenite was found to be reduced to elemental Se, forming colloidal particles. At hydrogen pressures of 10 bar, the rate of selenite reduction was found to be linearly correlated to the fraction of Pd in the UO₂ pellets. No selenium was detected on the surface of the pellets. For the lowest Pd loading (0.1% Pd) the selenite reduction does not appear to proceed to completion indicating that the surface becomes less active.     

L1 and L2 sub-shell fluorescence yields for elements with 64 ? Z ? 70

The L₁ and L₂ sub-shell fluorescence yields have been deduced for elements with 64 ? Z ? 70 from the L_k(k = l, α, β_1,4, β_3,6, β_2,15,9,10,7, γ_1,5 and γ_2,3,4) X-ray production cross sections measured at 22.6 keV incident photon energy using a spectrometer involving a disc type radioisotope of Cd¹⁰⁹ as a photon source and a Peltier cooled X-ray detector. The incident photon intensity, detector efficiency and geometrical factor have been determined from the K X-ray yields emitted from elemental targets with 20 ? Z ? 42 in the same geometrical setup and from knowledge of the K shell cross sections. The present deduced ω₁(exp) values, for elements with 64 ? Z ? 70, are found to be in good agreement with those tabulated by Campbell (J.L. Campbell, Atom. Data Nucl. Data Tables 95 (2009) 115), where as these are, on an average, higher by 19% and 24% than those based on the Dirac-Hartree-Slater model (S. Puri et al., X-ray Spectrometry 22 (1993) 358) and the semi-empirical values compiled by Krause (M.O. Krause, J. Phys. Chem. Ref. Data 8 (1979) 307), respectively. The present deduced ω₂(exp) values are found to be in good agreement with those based on the Dirac-Hartree-Slater model and are higher by up to ∼13% than the semi-empirical values for the elements under investigation.     

Oxidation of S（IV） in Seawater by Pulsed High Voltage Discharge Plasma with TiO2/Ti Electrode as Catalyst

Oxidation of S（IV） to S（VI） in the effluent of a flue gas desulfurization（FGD） sys- tem is very critical for industrial applications of seawater FGD. This paper reports a pulsed corona discharge oxidation process combined with a TiO2 photocatalyst to convert S（IV） to S（VI） in artificial seawater. Experimental results show that the oxidation of S（IV） in artificial seawater is enhanced in the pulsed discharge plasma process through the application of TiO2 coating electrodes. The oxidation rate of S（IV） using Ti metal as a ground electrode is about 2.0x10-4 mol. L 1. min-1, the oxidation rate using TiO2/Ti electrode prepared by annealing at 500 ~C in air is 4.5x 10-4 tool. L-a ~ min-1, an increase with a factor 2.25. The annealing temper- ature for preparing TiO2/Ti electrode has a strong effect on the oxidation of S（IV） in artificial seawater. The results of in-situ emission spectroscopic analysis show that chemically active species （i.e. hydroxyl radicals and oxygen radicals） are produced in the pulsed discharge plasma process. Compared with the traditional air oxidation process and the sole plasma-induced oxidation process, the combined application of TiO2 photocatalysts and a pulsed high-voltage electrical discharge process is useful in enhancing the energy and conversion efficiency of S（IV） for the seawater FGD system.     

Investigation of the level spectra of nuclei in the northeast region of doubly magic 40Ca with intruder orbit g9∕2

This study utilizes large-scale shell model calculations with the extended pairing and multipole–multipole force model(EPQQM) to investigate low-lying states in the nuclei of ⁴²Ca,⁴²Sc,and ^42-44Ti.The model space in this study includes the fp shell as well as the intruder g_9∕2 orbit,which accurately reproduces the positive parity levels observed in the aforementioned nuclei and predicts high energy states with negative parity coupled with the intruder ...     

Study on radiolabeling of 1,2,3-triazole analogs with fac-[188Re（CO）3 （H2O）3 ]+ via click chemistry

Click chemistry was used to study on radiolabeling of 1,2,3-triazole analogs with fac-[188 Re(CO) 3 (H 2 O) 3]+ . CuSO 4 /L-sodium ascorbate was chosen as the catalyst system, three terminal alkynes were conjugated with two different azides respectively, and then the new prepared fac-[188 Re(CO) 3 (H 2 O) 3]+ was coordinated to the six triazoles. The results showed that the radiochemical yields (RCY) of the conjugation of fac-[188 Re(CO) 3]+ with six triazoles were over 90%, and the triazoles showed high stability in phosphate-buffered saline and new-born calf serum. The preliminary biological evaluation results showed that the new 188 Re-labeling method via click chemistry could have general application in labeling bioactive molecules in high radiochemical yield and high specific activity for further SPECT research.     

Study on the corrosion behavior of 316H stainless steel in molten NaCl–KCl–MgCl2 salts with and without purification

The corrosion behavior of 316H stainless steel (SS) in the impure and purified Na Cl–KCl–Mg Cl₂ salt was investigated at700°C.Results indicate that the main deleterious impurity induced corrosion in the impure salt was the absorbed moisture,present in the form of Mg Cl₂·6H₂O.316H SS occurred severe intergranular corrosion with a corrosion depth of 130μm for1000 h in the impure Na Cl–KCl–Mg Cl₂ salt.In contrast,the purification treatment of molten chlor...     

Energy levels in Ag-like (4d4f, 4d5? (? = 0-3)), Pd-like (4d4f [J = 1], 4d5p [J = 1], 4d5f [J = 1]), and Rh-like (4d [J = 5/2, 3/2]) ions with Z ? 86

Relativistic perturbation theory with a model potential is used for the calculation of energy levels of the states 4f_5/2, 4f_7/2, 5s_1/2, 5p_1/2, 5p_3/2, 5d_3/2, 5d_5/2, 5f_5/2, and 5f_7/2 above the 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶4d¹⁰ core, with one vacancy , in the same core, in the silver and rhodium isoelectronic sequences with the maximum nuclear charge Z = 86. The method of extrapolation of the model potential parameter is applied to calculate one-electron and one-vacancy wavefunctions. The wavefunctions of Ag- and Rh-like ions were used to calculate the energies of resonance transitions to the ground state ¹S₀ in Pd-like ions. Good agreement between the theoretical and the experimental energies of the resonance transitions in Pd-like ions indicates the reliability of the results obtained.