Cross Sections Of Iron Research Articles

Characterization of Fast Neutron Transmission Through an Iron Shield

In this paper we give an analysis of the neutron transmission through an iron sphere using Monte Carlo and transport theory methods based on ENDF/B-VII.1 general purpose library. The motivation for this investigation comes from a well-known deficiency in the iron inelastic data from the older library evaluation (ENDF/B-V), giving a concern for a fast neutron flux underestimation within the reactor pressure vessels. In order to benchmark the next-generation ENDF/B-VI iron data, the U.S. Nuclear Regulatory Commission and the former Czechoslovakian National Research Institute have jointly preformed several experiments in 1990s, addressing neutron leakage spectra obtained for a 252Cf fission source in a centre of an iron sphere. It was shown that the ENDF/B-VI iron cross section, containing several improvements over previous evaluations, will not entirely resolve the neutron spectrum discrepancies observed at high neutron energies. Since safety analyses of reactor pressure vessel embrittlement are often based on neutron transport calculations using specific multigroup cross section libraries, simulation of this benchmark was performed using a hybrid shielding methodology of ADVANTG3.0.3 and MCNP6.1.1b codes. Comparison of calculated and referenced dosimeter activation rates are presented for several "standard" nuclear reactions, often used in reactor pressure vessel dosimetry. For that purpose, the new IRDFF-II special library from the IAEA Nuclear Data Services was used as a reference source of dosimetry cross sections. The MCNP6.1.1b code was used for calculation of reaction rates, which were also compared with previous IRDFF-1.05 special library and general purpose ENDF/B-VII.1 library.

Consistency Among the Results of the ASPIS Iron88, PCA Replica, and PCA ORNL Benchmark Experiments

Iron is an essential element in the construction materials for fission and fusion reactors. Due to its complexity, the evaluation of iron cross sections continues to represent a challenge for the international nuclear data community. A comprehensive validation of any new nuclear data evaluation (and the computational procedure) against experimental benchmarks is therefore needed. The shielding benchmark database SINBAD includes relatively numerous experiments with iron as a shielding material; altogether, 27 benchmarks and several more are known but have not yet been evaluated in the database. However, in order to use the benchmark information with confidence and to rely on the predictions based on integral benchmark calculations, it is crucial to verify the quality and accuracy of the measurements themselves, as well as the (completeness of) available experimental information. This is done in the scope of the benchmark evaluation process. A further check of the reliability of the experimental information can be achieved by intercomparing the results of similar types of benchmark experiments and checking the consistency among them.

Optimization of transformer parameters at distribution and power levels with hybrid Grey wolf-whale optimization algorithm

Oil-type transformers (OTT) are used more than dry-type transformers, based on cost in the transmission and distribution of electrical energy. Therefore, this usage density increases the importance of cost in OTT. Weight is important in transformer cost. The weight of the transformers depends on the variable parameters of the weights of the core and windings, C (iron cross section conformity factor) and s (current density), respectively. In this study, unlike the previous heuristic optimization studies, an innovative and complementary optimum weight was obtained by using the Gray Wolf - Whale Optimization hybrid algorithm for both distribution type and power transformer type OTT. A weight reduction of 44% and approximately 14% in power transformers was achieved. It was determined that this decrease in weights provided the same reduction in OTT costs. The comparison test of the study was performed both with the values of other algorithms and statistically.

Effect of annealing on the magnetic microstructure of high-pressure torsion iron: the relevance of higher-order contributions to the magnetic small-angle neutron scattering cross section.

The development of higher-order micromagnetic small-angle neutron scattering theory in nanocrystalline materials is still in its infancy. One key challenge remaining in this field is understanding the role played by the microstructure on the magnitude and sign of the higher-order scattering contribution recently observed in nanocrystalline materials prepared by high-pressure torsion. By combining structural and magnetic characterization techniques, namely X-ray diffraction, electron backscattered diffraction and magnetometry with magnetic small-angle neutron scattering, this work discusses the relevance of higher-order terms in the magnetic small-angle neutron scattering cross section of pure iron prepared by high-pressure torsion associated with a post-annealing process. The structural analysis confirms: (i) the preparation of ultra-fine-grained pure iron with a crystallite size below 100 nm and (ii) rapid grain growth with increasing annealing temperature. The analysis of neutron data based on the micromagnetic small-angle neutron scattering theory extended to textured ferromagnets yields uniaxial magnetic anisotropy values that are larger than the magnetocrystalline value reported for bulk iron, supporting the existence of induced magnetoelastic anisotropy in the mechanically deformed samples. Furthermore, the neutron data analysis revealed unambiguously the presence of non-negligible higher-order scattering contributions in high-pressure torsion iron. Though the sign of the higher-order contribution might be related to the amplitude of the anisotropy inhomogeneities, its magnitude appears to be clearly correlated to the changes in the microstructure (density and/or shape of the defects) induced by combining high-pressure torsion and a post-annealing treatment.

Electron-impact ionization cross sections of small molecules containing Fe and Cr ∗ ∗ This work is dedicated to Enrico Clementi who pioneered the interdisciplinary use of quantum chemistry and computational modelling.

We present the electron-impact ionization cross sections (EICSs) of iron and chromium hydrides, nitrides, and oxides. The motivation of this work stems from the fact that chemical sputtering from a steel surface exposed to a hot plasma can create these molecules which in turn influence the composition and energy balance of the plasma. The latter influence is quantified by the EICS which we derive by using two semi-empirical methods which can be employed in the relevant energy range of 10–1000 eV. They are important molecular properties for plasma- and materials science. We discuss the foundations of the methods and present the cross sections of the high- and low-spin states of the species in their neutral ground states and of their cations.

The effect of heavy reflector on neutronic parameters of core

The reactor baffle is an important component of a nuclear reactor that fixes the location of the fuel assembly in the reactor core. The main types of baffles are called light or heavy. The light baffle has mostly the form of steel plates with outer space filled by water, and the heavy baffle is mostly a forged steel element. Both concepts have advantages as well as disadvantages. In the case of the light baffle, one does not need to solve the issue of void swelling, but the neutron economy is not ideal, while the heavy baffle has a good neutron economy, but void swelling is an issue. This paper deals with the effect of the heavy VVER-1000 baffle on criticality. Criticality was measured using a well-defined core composed of 6 fuel assemblies moved to a simulator of the VVER-1000 internals, which is located at the LR-0 reactor. The experiments confirm the fact that the water filling the cooling channels in the baffle has a strong neutron-absorbing effect. The keff calculated using the ENDF/B-VIII.0 library significantly underpredicts the experiment. The calculations using a new evaluation of 56Fe by the IAEA (INDEN collaboration) do not improve the situation significantly. Generally, the presented results are suitable for the validation of iron cross sections.

The Application of Silicon-Filtered Beam in the Validation of Iron Cross Sections by Deep Penetration Experiments

Abstract This paper summarizes the issue of the validation of the silicon-filtered neutron beam transport in the deep neutron transport penetration experiment in iron. Iron is an essential structural material important for nuclear technology. The use of a silicon-filtered beam is a very interesting method because some significant peaks occur in the spectrum, helping to study selected wide energy regions during the deep neutron transport in the iron. The detailed characterization of the silicon-filtered beam has been performed in the past as well. Therefore, the input spectrum for the penetration experiments is well-known. The character of the input spectrum is reflecting the fine structure of the silicon cross section in region 1–8 MeV. Based on the agreement between calculated and measured attenuation in groups located within the neutron flux peaks, one can reveal possible problems in neutron transport description. The results are confirming satisfactory agreement of neutron transport description in ENDF/B-VII.1 in the majority of energy regions, while in the interval 4.7–6 MeV, underprediction in attenuation can be observed. This seems to be a consequence of discrepancies in the angular distribution of scattered neutrons. These results constitute an advance to previously performed integral experiments characterizing the neutron transport in iron using 252Cf(s.f) and 235U(nth;fiss).

Structure and properties forming in ductile iron during isothermal hardening using ultrasound

The paper considers the possibility of intensifying isothermal holding processes during quenching of high-strength cast irons by using an external source of physical impact in the form of ultrasonic waves. For experimental evaluation of this effect in the laboratory of MiAM of the Physical-Technical Institute of the National Academy of Sciences of Belarus, prototypes of highstrength cast irons were cast in an ISV 0.004 crucible induction furnace. A mixture of NaNO2 and KNO3 salts in a 1:1 ratio was used as a liquid cooling medium during quenching. Ultrasonic treatment of the salt melt during the cooling of the samples was carried out using an UZG-20–15 generator in cooperation with the ITA of NAS of Belarus. The mechanical properties and structure of the treated cast irons were determined both in the cast state and after isothermal quenching.To study the effect of ultrasonic treatment of the quenching bath on the formation of the structure and properties of highstrength cast irons during isothermal quenching, a number of comparative experiments were carried out, consisting in cooling the samples from 910 °C to 350 °C with and without the use of dynamic waves to the bath. With the help of metallographic analysis, measurements of hardness and friction coefficient, the beneficial effect of ultrasonic treatment of the cooling medium on the structure and properties is shown, which is reflected in an increase in the uniformity of the distribution of hardness over the cross section of cast iron and in its wear resistance, as well as a reduction in the isothermal holding time by up to two times.

Measurement of tungsten granular target worth on VENUS-II light water reactor and validation of the granular target model

In this paper, a benchmark experiment of tungsten granular target worth has been performed on the VENUS-II light water zero-power facility of CIAE in Beijing. The reactivity worth of the tungsten granular target was measured and processed as (-1.007±0.096) mk by a period method. In MCNP simulations, three modeling methods of tungsten grains, i.e., the homogeneous, body center and face center models, were used to calculate the tungsten granular target reactivity worth. Through the comparison, the simulated tungsten granular target reactivity worth values with three modeling methods are in good agreement with the experimental result within errors and the maximum C/E and (C-E) deviations are respectively 3.7% and 0.037 mk. By the perturbation analysis in MCNP and the comparison on the cross sections of tungsten, iron and nickel, the negative reactivity worth of tungsten granular target is mainly caused by the tungsten radiation capture reaction channel. It is recommended to adopt the efficient homogeneous modeling method to simulate the tungsten granular target, which establishes a foundation for the systematic integration design of CIADS.

Benchmark experiment of large-angle scattering reaction cross section of iron at 14 MeV using two shadow bars – Comparison of experimental results with ENDF/B-VIII –

ABSTRACT It is important to perform neutron transport simulations with accurate nuclear data in the neutronics design of a fusion reactor. However, absolute values of large-angle scattering cross sections vary among nuclear data libraries even for well-examined nuclide of iron. Benchmark experiments focusing on large-angle scattering cross sections were thus performed to confirm the correctness of nuclear data libraries. The series benchmark experiments were performed at a DT neutron source facility, OKTAVIAN of Osaka University, Japan, by the unique experimental system established by the authors’ group, which can extract only the contribution of large-angle scattering reactions. This system consists of two shadow bars, target plate (iron), and neutron detector (niobium). Two types of shadow bars were used and four irradiations were conducted for one experiment, so that contribution of room-return neutrons was effectively removed and only large-angle scattering neutrons were extracted from the measured four Nb reaction rates. The obtained experimental results were compared with calculations for five nuclear data libraries including JENDL-4.0, JEFF.-3.3, FENDL-3.1, ENDF/B- VII, and recently released ENDF/B-VIII. It was found from the comparison that ENDF/B-VIII showed the best result, though ENDF/B-VII showed overestimation and others are in large underestimation at 14 MeV.

Displacement damage study in tungsten and iron for fusion neutron irradiation

In the present paper, displacement damage in tungsten and iron are studied using the TALYS-1.8 code and molecular dynamics simulations. The TALYS-1.8 code is used to predict the energy spectra of recoils. The MD simulations of self-recoils of up to 200 keV damage energies are carried out to predict the number of Frenkel pairs in iron and tungsten using the LAMMPS code. Time evolution of vacancies and interstitials are studied and discussed. The results of MD simulations are used to calibrate the constant parameters of the Arc-dpa method. The displacement damage cross section of tungsten and iron are calculated for the neutron irradiation of up to 15 MeV energy with the NRT and Arc-dpa approaches. The dpa (Arc-dpa) value at the first wall location of EU DEMO reaches 1.19 dpa/FPY and 0.93 dpa/FPY in iron and tungsten, respectively. Similarly, dpa values in iron and tungsten are also predicted at different neutron fields using the NRT and Arc-dpa mechanism.

Test Result of the HL-LHC Beam Separation Dipole Model Magnet With the New Iron Cross Section

We report the test results of the second short model magnet of the beam separation dipole for the High Luminosity Large Hadron Collider. The test shows that the second model has a good training performance and is capable of operating at the ultimate current that corresponds to 108% of the nominal one. Magnetic field measurements reveal that b 3 is around 18 units, which is 15 units higher than the calculations. This can be explained in part by geometrical coil deformation caused during the construction process.

Development of 2-m Model Magnet of the Beam Separation Dipole With New Iron Cross Section for the High-Luminosity LHC Upgrade

Large aperture beam separation dipoles (D1 magnet) must be developed for the interaction regions in the high-luminosity large hadron collider (HL-LHC). The most important specifications of this magnet are a coil aperture of 150 mm and field integral of 35 Tm, which will be realized by Nb-Ti superconducting magnets operated at 12 kA at 1.9 K. High Energy Accelerator Research Organization (KEK) is developing 2-m-long model magnets for D1. The first model magnet was re-assembled after increasing the coil pre-stress (MBXFS1b); subsequently, it showed good training performance, achieving maximum quench current, which was higher than the ultimate current. However, mechanical support of the coils was still insufficient in MBXFS1b. Especially at coil end, some coil end blocks deformed toward the coil bore due to Lorentz force. In the second model magnet (MBXFS2), the change of iron yoke cross section was requested so that the position of heat exchanger holes penetrating iron yoke is in agreement with those of the final focusing Nb 3 Sn quadrupole magnets. Because this has a large impact on field quality, magnetic design including the magnet's cross section and coil end shape was updated. Some countermeasures were also taken to enhance mechanical support of the coil such as wet-winding with radiation-resistant resin at coil end and increase in coil pre-stress. This paper reports design update, fabrication, and training performance of MBXFS2 with new iron cross section.

The Effect of Internal Free Surfaces on Void Swelling of Irradiated Pure Iron Containing Subsurface Trenches

We studied the effects of internal free surfaces on the evolution of ion-induced void swelling in pure iron. The study was initially driven by the motivation to introduce a planar free-surface defect sink at depths that would remove the injected interstitial effect from ion irradiation, possibly enhancing swelling. Using the focused ion beam technique, deep trenches were created on a cross section of pure iron at various depths, so as to create bridges of thickness ranging from 0.88 μm to 1.70 μm. Samples were then irradiated with 3.5 MeV Fe2+ ions at 475 °C to a fluence corresponding to a peak displacement per atom dose of 150 dpa. The projected range of 3.5 MeV Fe2+ ions is about 1.2 μm so the chosen bridge thicknesses involved fractions of the ion range, thicknesses comparable to the mean ion range (peak of injected interstitial distribution), and thicknesses beyond the full range. It was found that introduction of such surfaces did not enhance swelling but actually decreased it, primarily because there were now two denuded zones with a combined stronger influence than that of the injected interstitial. The study suggests that such strong surface effects must be considered for ion irradiation studies of thin films or bridge-like structures.

Investigation of Neutron Cross Section for Iron in the ENDF Library with Pulsed Sphere Measurements

This work investigates the quality of the ENDF 56Fe cross-section libraries for describing the transport of fast neutrons in iron. We have used the D(d,n)3He reaction with a pulsed 7-MeV deuteron beam energy as a neutron source and analyzed the neutrons transmitted through two natural iron spheres of thicknesses 3 and 8 cm. The experimental neutron time-of-flight transmitted spectra for various angles are compared with MCNP simulations. Our result indicates the possibility of an underestimation of the nonelastic cross section and an overestimation of the elastic cross section for 56Fe in the ENDF/B-VII.1 library for the neutron energy range of 7.2 to 10.2 MeV. Our result agrees qualitatively with the Ramsauer model and optical model calculations. This discrepancy in the library cross section might lead to an underestimation/overestimation of material damage in nuclear reactor calculations. A newer evaluation, ENDF/B-VIII.0, was released subsequent to the completion of the majority of this project. The new evaluation has a decreased elastic cross section and an increased inelastic cross section for 56Fe in our energy range of interest, which agrees qualitatively with our result.

Effect of Pulse Repetition Rate on Micro Hardness on the Surface and Cross Section of Gray Cast Iron by using ND-YAG Laser

Effect of Pulse Repetition Rate on Micro Hardness on the Surface and Cross Section of Gray Cast Iron by using ND-YAG Laser

Level-resolved Photoionization Cross Sections for Fe i

Abstract Significant contributions to the UV opacity in the solar atmosphere have been found to stem from bound-free transitions in neutral iron. As such, accurate cross sections for the photoionisation process are required for a detailed and meaningful analysis. However, existing photoionisation cross sections display large discrepancies across the low-energy region, highlighting the need for further calculations. In this work, we present level-resolved photoionisation cross sections for neutral iron across a wide energy range from a 262 level Dirac R-matrix calculation. Comparisons with existing experimental measurements reveal good agreement in the positions of the various low-energy resonance features. However, additional comparisons with theoretical data sets highlight wide variations. Significant resonance structures at high photon energies are explored by employing an additional series of 262 level and 896 level Dirac R-matrix calculations with a smaller six configuration target. The resulting photoionisation cross sections reproduce the main features from existing experimental observations. The results presented throughout will be useful to those requiring an extensive set of level-resolved photoionisation cross sections for astrophysical applications.

Cross section and neutron angular distribution measurements of neutron scattering on natural iron

New measurements of the neutron scattering double differential cross section of iron were carried out at the neutron time-of-flight facilities GELINA and nELBE. A neutron spectrometer consisting of an array of up to 32 liquid organic scintillators was employed, which was designed to measure the scattering differential cross section at eight scattering angles and to simultaneously determine the integral cross section via numerical quadrature. The separation of elastic from inelastic scattering was achieved by analyzing the time-of-flight-dependent light-output distributions to determine the scattered neutron energy. The method was validated by studying elastic scattering on carbon and it was proved to work well for the determination of the elastic cross section. Here, the possibility to extend it to inelastic scattering was investigated too. For these experiments a sample of natural iron was used and the results cover the incident neutron energy range from 2 to 6 MeV. Both the differential and the integral elastic cross sections were produced for $^{\mathrm{nat}}\mathrm{Fe}$, while for inelastic scattering, partial angular distributions for scattering from the first excited level of $^{56}\mathrm{Fe}$ could be determined.

Investigation on the surface layer formed during electrochemical modification of pure iron

This paper presents an experimental and analytical investigation on electrochemical modification of pure iron, aiming to obtain a surface layer which has good machinability for further processing. The microstructures of the modified layer were compared from a relative low current density (10 A/cm2) to high current density (30 A/cm2) and characterized by various detection equipment. A detailed X-ray photoelectron spectroscopy (XPS) analysis was conducted to measure the composition profile of the black film on the modified layer. The results show that, during electrochemical modification, the subsurface formed a loose porous layer covered with a flimsy oxide. At low current density, uniform dissolution was obtained and the surface was not corroded off completely. However, at large current density, due to the strong electrochemical action and uneven flow field, the cross section of pure iron became waved and the surface shape deteriorated. The results of the water contact angle measurements show that the surface hydrophilicity was enhanced by electrochemical modification, which might improve the cooling effect of the machining region. The XPS analysis indicated a bi-layer structure of oxidation film on the modified layer and the outmost Fe3+ species layer was considered to be the oxidation of Fe2+ species from inner layer.

Calculation of the Mott Scattering cross section for Iron and Silver in the energy range (50keV-10MeV)

In the present research work, we tableted the ratio of Mott to Rutherford cross section ( ), for Iron and Silver atoms by employing Mckinley - Fashbach equation , in the range of incident electron energy (50KeV-10MeV), by adopting the equations used in the presen calculations by using Visual Basic 2010. The results shows that the ratio ( is mostly influenced with two parameters :incident electron energy and atomic number of the target material on the Mott cross section. The obtained results were compared with previous results, and they shows a good agreement, and his confirms the validity of the equations used in the employed energy range.