Displacements per atom (dpa), estimated based on the standard Norgett–Robinson–Torrens (NRT) model, is used for assessing radiation damage effects in fast reactor materials. A computer code CRaD has ...been indigenously developed towards establishing the infrastructure to perform improved radiation damage studies in Indian fast reactors. We propose a method for computing multigroup neutron NRT dpa cross sections based on SRIM-2013 simulations. In this method, for each neutron group, the recoil or primary knock-on atom (PKA) spectrum and its average energy are first estimated with CRaD code from ENDF/B-VII.1. This average PKA energy forms the input for SRIM simulation, wherein the recoil atom is taken as the incoming ion on the target. The NRT-dpa cross section of iron computed with “Quick” Kinchin-Pease (K-P) option of SRIM-2013 is found to agree within 10% with the standard NRT-dpa values, if damage energy from SRIM simulation is used. SRIM-2013 NRT-dpa cross sections applied to estimate the integrated dpa for Fe, Cr and Ni are in good agreement with established computer codes and data. A similar study carried out for polyatomic material, SiC, shows encouraging results. In this case, it is observed that the NRT approach with average lattice displacement energy of 25 eV coupled with the damage energies from the K-P option of SRIM-2013 gives reliable displacement cross sections and integrated dpa for various reactor spectra. The source term of neutron damage can be equivalently determined in the units of dpa by simulating self-ion bombardment. This shows that the information of primary recoils obtained from CRaD can be reliably applied to estimate the integrated dpa and damage assessment studies in accelerator–based self-ion irradiation experiments of structural materials. This study would help to advance the investigation of possible correlations between the damages induced by ions and reactor neutrons.
A rapid increase in the use of non-biodegradable plastics and their disposal after use has had a detrimental impact on the environment. Used plastics (used low-density polyethylene - ULDP) were ...selected as feedstock for the extraction of pyrolytic oil. The pyrolysis process was carried out in a semi-batch reactor with a silica alumina catalyst in the existence of fluidizing gas N
2
in a reactor at 500 °C for 60 min. The maximum liquid, gas, and char yields were 93.5 wt%, 5.4 wt%, and 1.1 wt%, respectively. Experimental analysis was carried out to obtain their functional and structural groups by FT-IR and the carbon distribution was identified by GC-MS analysis. The blends of 20%, 40%, 60%, 80%, and 100% on a volume basis were chosen for the detailed study. For the pyrolytic blends, the combustion, performance, and emission characteristics were tested at different engine loads. During combustion, the heat release rate was extremely high for neat ULDP oil because of the high energy content and a higher cetane index. The efficiency of ULDP20 was higher than in other blends, whereas NOx and smoke emissions of ULDP20 were lower among the blends but higher than diesel. ULDP20 performed similarly as diesel. Hence, ULDP20 is recommended as a fuel for the diesel engine.
Lower acidity ratio of SA catalyst influences higher yield of ULDP oil and is suggested as a novel fuel for unmodified diesel engine.
The primary radiation damage (PRD) in structural materials is generally assessed in terms of the displacements per atom (dpa). The athermal recombination corrected displacements per atom (arc-dpa) ...model, used to predict PRD in materials has been incorporated in the Kalpakkam code CRaD. A recent parameterization of the arc-dpa model for various materials by Konobeyev et al. is available. This parameterization has facilitated a comparison between the predictions of the PRD levels in structural materials from NRT and arc-dpa models by using the CRaD code. A reference database of neutron dpa cross sections has been created by CRaD based on these two models by using the data from ENDF/B-VII.1 nuclear data library. The erstwhile design manuals of nuclear systems would have a specified limit of dpa towards life time integrity corresponding to methods and nuclear data used at that time. The new design manuals will have the same engineering damage correlated to the revised value of the dpa corresponding to the use of improved models of dpa and updated nuclear data for the same irradiation conditions. Therefore, the rescaling of dpa versus engineering damage is necessary, as the dpa is presently calculated using improved basic evaluated nuclear data and models for atom-displacement damage. The design life of nuclear systems is determined by the irradiation conditions, but the rescaling of dpa in the correlations of dpa versus damage makes sure that the updated dpa obtained with new data and methods is used correctly in design studies.
•Impact of recent ENDF-6 libraries on neutron heating and the relative merits of direct and energy balance methods of its estimation are investigated in detail in this paper.•The variation of neutron ...kerma under irradiation in fast and fusion neutron spectra is also studied.•Further, the nuclear data uncertainties are also quantified using the TMC method.
The generation of heat due to interaction of neutrons with matter is an important aspect in the designing of nuclear reactors. The estimation of neutron heating depends profoundly on the evaluated nuclear reaction parameters. Hence, within the purview of radiation damage of materials, it is necessary to investigate the effects of improvements in nuclear databases on the neutron heating rates under various neutron spectra. There are two well established methods to quantify the neutron kerma coefficients in matter: energy balance method and direct method. The well established code like NJOY21 gives the energy balance neutron kerma. In this study, the importance and performance of the direct method has been investigated, as the recent general purpose basic evaluated nuclear data files provide more complete database. Though both the methods predict closely the reported measured values of neutron kerma coefficients for structural elements, significant differences are observed between these two methods at higher energies where contributions from charged particle emitting reactions become important. The direct method is found to be more meaningful as it always ensures positive kerma coefficients and helps to separately identify the contributions from light charged particles and recoil nucleus. The neutron spectrum dependence of neutron kerma from both the methods are also investigated. Further, the nuclear data uncertainties in neutron heating are quantified by the Total Monte Carlo (TMC) methodology using the random ENDF-6 files in TENDL-2015 and the results show that the nuclear data uncertainties are in the range of 9–29%.
The neutronics analysis of selected start-up tests conducted from 2010 to 2011 in China Experimental Fast Reactor (CEFR) is carried out using in-house FARCOB and European ERANOS-2.1 code systems as a ...part of IAEA coordinated research project (CRP) on "Neutronics Benchmark of CEFR Start-Up Tests". This exercise has the main objective of validation and verification of physical models, neutronics simulation methodology including cross-section libraries that is used for fast reactor core simulations. It is challenging to simulate such a small compact core of enriched uranium with high neutron leakage having stainless steel radial reflector by using 3-D diffusion theory codes. This benchmark analysis used a new simplified approach such as a 3-step method and experimental method for simulating temperature and sodium void reactivity coefficients. Net criticality, control rod worth, temperature and sodium void reactivity coefficients and swap reactivity could be predicted well within their measured error values. This exercise provided an additional validation of the FARCOB system against small sodium-cooled fast reactor (SFR) cores, and it can be confidently used for the design and analysis of small experimental reactor cores.
Experimental tests have been carried out to evaluate the performance, emission and combustion characteristics of a diesel engine using Neat poon oil and its blends of 20%, 40%, and 60%, and standard ...diesel fuel separately. The common problems posed when using vegetable oil in a compression ignition engine are poor atomization; carbon deposits, ring sticking, etc. This is because of the high viscosity and low volatility of vegetable oil. When blended with diesel, poon oil presented lower viscosity, improved volatility, better combustion and less carbon deposit. It was found that there was a reduction in NO
x
emission for Neat poon oil and its diesel blends along with a marginal increase in HC and CO emissions. Brake thermal efficiency was slightly lower for Neat poon oil and its diesel blends. From the combustion analysis, it was found that poon oil–diesel blends performed better than Neat poon oil.
•Synthesis of NiO assembled TiO2 composites using ultrasound assisted wet impregnation method•Coupling of wide band-gap NiO with TiO2 enhances the absorption to visible region•A synergistic of 4.8 ...fold is achieved when ultrasound is combined with photocatalysis under diffused sunlight•The reduction of TOC confirms the mineralization of MO dye•TiO2–NiO composite shows higher photocurrent response than bare TiO2
TiO2–NiO composites with p–n junction were developed by assembling p-type NiO on n-type TiO2 using ultrasound assisted wet impregnation method. The sonophotocatalytic efficiencies of pure TiO2 and TiO2–NiO composites were evaluated under diffused sunlight using methyl orange (MO) as a model pollutant. The impregnation of NiO nanoparticles on TiO2 considerably enhanced the optical absorption in visible region (500–800nm) due to the formation of p–n junctions at the interface between TiO2 and NiO. The internal electric field induced by the p–n junction led to effective separation of electron–hole pairs and thereby generating a large amount of reactive species for the degradation of MO. The individual effect of ultrasound and diffused sunlight for the degradation of MO was found to be 30% and 6%, respectively. A synergy of 4.8 fold was achieved when ultrasound was combined with photocatalytic degradation process in the presence of diffused sunlight. The sonophotocatalytic activity of TiO2–NiO photocatalysts with different NiO loading was also evaluated and 10wt% NiO loading was found to be optimal. Moreover, 66% of Total Organic Carbon (TOC) removal was achieved with the optimized TiO2–NiO composite in 140min. In addition, the TiO2–NiO composite exhibited an enhanced photocurrent response under visible light illumination.
The primary radiation damage formation in materials subjected to neutron radiation is very sensitive to the energy spectra of primary knock-on atoms (PKAs) and their collision cascade in the crystal ...lattice. The estimated values of the primary radiation damage metrics, such as displacements per atom (dpa) cross sections, integrated dpa, PKA spectrum and spectrum averaged PKA energy are uncertain because of uncertainties present in both the basic nuclear reaction data and the displacement damage model parameters. The Total Monte Carlo (TMC) methodology, which uses the random evaluated nuclear data files for nuclides, is well recognized to propagate the uncertainties in basic nuclear data to the derived quantities in nuclear reactor physics. The uncertainties in the above mentioned primary radiation damage parameters are obtained in this study by propagating the uncertainties in basic evaluated nuclear data, following the TMC methodology. The knowledge of uncertainties in the spectrum averaged PKA energies also enables us to ascertain the uncertainties in the production of vacancies through self-ion simulations using SRIM-2013 code. The present study is an outcome of our systematic approach towards establishing the procedure. This includes pre-processing a large number of TENDL nuclear data random files using NJOY-2016, developing an indigenous code CRaD for handling these point and multigroup data libraries and computing primary radiation damage metrics and their associated uncertainties including energy-energy and nuclear reaction channel-channel correlation matrices. The uncertainties in dpa cross sections and PKA spectra due to uncertainties in basic nuclear data are found to be comparatively larger than the uncertainties in respective integrated parameters; viz. dpa and average PKA energy. This study also confirms the non-Gaussian distributions of derived primary radiation damage parameters.
An accurate estimation of production of gases due to interactions of neutron in structural materials of nuclear systems is an important aspect within the purview of studies of primary radiation ...damage. Towards this objective, the indigenous code CRaD, which computes neutron primary radiation damage due to displacements of atoms, has been added with the capability to compute gas production for applications in Indian fast reactors. It includes the computation of gas production cross sections by using standard ENDF-6 procedure, estimation of gases in structural materials due to different types of neutron spectra and propagation of nuclear data uncertainties by Total Monte Carlo (TMC) methodology. A comparison of gas production cross sections from CRaD and NJOY (NJOY-2016.31 and NJOY21) is made and a few discrepancies noted with the processing of charged particle production cross sections using the above versions of NJOY are briefly outlined. A simple linear transmutation methodology is adapted in CRaD to estimate the concentrations of gases and validated with the published theoretical data which were obtained using a similar methodology. The study shows that the representation of charged particle data in different ENDF-6 files is not unique and spectrum-averaged gas production cross sections show large variations. The effect of spread in the activation cross sections from different libraries on the two-step processes of gas production in Nickel under different spectra is also discussed. Detailed TMC-based statistical analyses of gas production in Fe are performed and the mean, standard deviation, skewness and channel-wise and isotope-wise correlation coefficients are quantified. The uncertainties in the production of gases in Fe are estimated to be in the range of 16–56%, with the larger uncertainties being observed in the productions of tritium and helium-3 gases. The gas production parameters have shown non-Gaussian distributions.
The proposed work introduces a dual-stage deep capsule autoencoder (DSDC-AE) model for fake news detection on Twitter data. Initially, the input Twitter data are pre-processed using tokenisation, ...stemming, stop word removal and lemmatisation. The text features are extracted from the pre-processed data using Improved Term Frequency Inverse Document Frequency (ITF-IDF), Unigrams, Bigrams, Enhanced Bag of Words (EBoW) and Advanced Word2vec (Word2 Vector). To minimise the large feature dimensionality, the proposed work uses the Horse Herd Optimisation algorithm (HOA) for the feature selection. Finally, the selected features are subjected to the proposed classifier, in which the fake news from Twitter data is detected and classifies the given input data as real or fake. The proposed DSDC-AE model uses three datasets for the analysis: fake news detection on Twitter EDA, ISOT dataset and FakeNewsNet dataset. The mentioned dataset obtains the accuracy of 99.52%, 99.51% and 99.47%.
PDF
