Frontiers in Nuclear Engineering最新文献

{"title":"Optimisation of the chemical oxidation reduction process (CORD) on surrogate stainless steel in regards to its efficiency and secondary wastes","authors":"A. Rivonkar, R. Katona, Mathurin Robin, T. Suzuki-Muresan, A. Abdelouas, M. Mokili, G. Bátor, T. Kovács","doi":"10.3389/fnuen.2022.1080954","DOIUrl":"https://doi.org/10.3389/fnuen.2022.1080954","url":null,"abstract":"Nuclear Power is a decarbonated technology of electrical energy generation. Using nuclear energy as a power source is currently considered as the best option in the fight against climate change. But the radioactive waste generated from nuclear power plants and their related facilities are matter of concern. Though the high level and intermediate level activity wastes are contained in small volumes (≤10%), significant volumes of lower activity wastes are generated. Metallic wastes are a major component of these radioactive wastes with about 500,000 tons expected in France alone, including 130,000 tons from steam generators. Majority of these metals are made of Stainless steel 316 alloy or Inconel 600. Under the effect of the primary circuit thermal-hydraulic constraints and irradiation, these the resulting corrosion products may be activated when close to the fuel, and be transported throughout the circuit. These products can be deposited on the surface of other metal components, causing contamination of the latter. The contamination can be adsorbed on the surface but can also diffuse in the oxide layers and sub-surface. The oxide layer is composed of an inner layer of Cr oxide under a layer of Ni and Fe oxide. Chemical decontamination is preferred due to the possibility of decontamination of difficult geometries and tube bends. In order to decontaminate these materials, it is important to dissolve the oxide layers chemically and a few micrometers of base metal where it could have diffused. An existing chemical method used to treat these materials is studied in this article, Chemical Oxidation Reduction Decontamination (CORD). Surrogate steel samples were prepared using high temperature induction heating and water vapour after sample preparation and cleaning. The oxide layer was characterised before treatment of the samples in the batch method at different concentrations and its effects are observed on the dissolution of the oxide layers. A protocol is being developed for the treatment of secondary waste effluents by multi-stage precipitation with a goal to reduce the total waste volumes and thus the volumes of ion exchange resins that would otherwise be needed.","PeriodicalId":400400,"journal":{"name":"Frontiers in Nuclear Engineering","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130370827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Perspective on “code qualifying” new graphite grades for use in advanced nuclear reactors*","authors":"A. Campbell","doi":"10.3389/fnuen.2022.1045607","DOIUrl":"https://doi.org/10.3389/fnuen.2022.1045607","url":null,"abstract":"The American Society of Mechanical Engineers (ASME) publishes the Boiler and Pressure Vessel (BPV) Code, which include guidance for the safe development, construction, and operation of boilers and pressure vessels. ASME BPV Code Section III “Rules for Construction of Nuclear Facility Components” Division 5 focuses on “High Temperature Reactors”. Subsection HH, subpart A lists the different materials properties that are to be measured and how those properties change due to different environmental conditions (oxidation and irradiation damage) for a graphite to be accepted for use in a high temperature reactor core (i.e., “Code Qualified”). Currently there are no nuclear graphite grades that are “Code Qualified” (i.e., a reactor designer can select a graphite grade and build their reactor without any additional testing), which is due in part to development of new graphite grades in the last 20 years and the lack of comprehensive programs needed to produce the data for the code cases. This perspective is going to discuss the requirements, as called out in the ASME BPV Code, that are necessary to “code qualify” a nuclear graphite grade but will primarily focus on the practical and technical challenges associated with irradiation-induced property changes and how to address these to assist with getting graphite ready for use in advanced nuclear reactors. These same technical challenges can be expected to arise for other materials being developed for advanced reactor concepts.","PeriodicalId":400400,"journal":{"name":"Frontiers in Nuclear Engineering","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127035690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mini review of research requirements for radioactive waste management including disposal","authors":"B. Grambow","doi":"10.3389/fnuen.2022.1052428","DOIUrl":"https://doi.org/10.3389/fnuen.2022.1052428","url":null,"abstract":"This brief overview of research needs related to radioactive waste management and disposal is intended to provide a framework for addressing some important research questions related to historical developments and some large industrial mega-projects for geological disposal of radioactive waste that are currently being developed. Considering that the level of industrial development varies considerably between countries, research in this field of knowledge has a strong international and long-term orientation, encompassing both basic and applied research, including optimisation.","PeriodicalId":400400,"journal":{"name":"Frontiers in Nuclear Engineering","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134492287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of swift heavy ion irradiation and annealing on the microstructure and recrystallizationof SiC pre-implanted with Sr ions","authors":"H. Abdelbagi, T. Jafer, V. Skuratov, E. Njoroge, M. Mlambo, T. Hlatshwayo, J. Malherbe","doi":"10.3389/fnuen.2022.1034114","DOIUrl":"https://doi.org/10.3389/fnuen.2022.1034114","url":null,"abstract":"Polycrystalline SiC wafers were implanted with 360 keV strontium (Sr) ions at room temperature (RT)to a fluence of 2 × 1016 cm−2. Some of the implanted samples were irradiated with xenon (Xe) ions of 167 MeV to a fluence of 3.4 × 1014 cm−2 and 8.4 × 1014 cm−2at RT. The as-implanted and implanted then irradiated samples were vacuum annealed (isochronally) at temperatures ranging from 1,100 to 1,400°C in steps of 100°C for 5 h. Annealing induced modification of the microstructure of the implanted and swift heavy ions (SHIs) irradiated SiC was studied by Raman spectroscopy, scanning electron microscopy (SEM) and backscattering spectrometry (RBS). Sr ions bombardment caused formation of an amorphous layer in SiC, while irradiation by Xe ions led to partial recrystallization of the amorphized layer. After annealing at 1,100°C, the samples with low Sr retained ratio showed full recrystallization, while the samples with high Sr retained ratio showed poor recrystallization. This suggests that the presence of Sr within the implanted region inhibited the recrystallization of SiC. Annealing of the as-implanted samples at temperatures from 1,100°C and 1,200°Cresulted in larger average crystal size compared to the SHIsirradiated samples annealed in the same temperature range. The difference in the average crystal sizes between the as-implanted and SHIs irradiated samples was due to the differences in the nucleation rate per amorphous area in the two samples. Ramanspectroscopy results showedthat the intensity of the LO mode of SiC increases with increasing crystal size. However, several factors such as pores and defects in SiC play a role in the decrease of the LO mode intensity of SiC (even if the average crystal size is large).","PeriodicalId":400400,"journal":{"name":"Frontiers in Nuclear Engineering","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117039978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neptunium mononitride as a target material for Pu-238 production","authors":"K. Peruski","doi":"10.3389/fnuen.2022.1044657","DOIUrl":"https://doi.org/10.3389/fnuen.2022.1044657","url":null,"abstract":"Deep space exploration requires specialized sources for both thermal and power applications. Radioactive decay heat of plutonium-238 (238Pu) provides these sources in the form of radioisotope thermoelectric generators (RTGs). The 238Pu is produced via neutron capture reaction involving neptunium-237 (237Np) target material. Continual optimization of 237Np target materials and evaluation of potential alternative targets for production of 238Pu RTGs are advantageous for meeting ongoing space power system resource requirements. Current production of 238Pu for RTGs for the United States space program utilizes neptunium dioxide (237NpO2) targets; however, the use of neptunium mononitride (237NpN) presents an opportunity to increase the mass of 237Np per target compared to the dioxide form, as well as increase the thermal conductivity of the target. To assess the viability of a 237NpN target material, the material chemistry must be thoroughly evaluated, including synthesis methods and dissolution and reprocessing schemes. This review presents a summary of synthesis pathways for 237NpN based on published literature on actinide mononitrides. Specific literature on 237NpN is limited, necessitating evaluation of other actinide systems to gather parallels. This suggests a need for additional experimental studies on 237NpN. A particular limitation in the existing literature is a lack of information on the differences in material characteristics, such as morphology, particle size, and trace chemical impurities, as a function of synthesis method. These parameters may affect subsequent reactor performance or dissolution of irradiated targets. The evaluation of existing literature is presented with a focus on the efficacy of 237NpN targets for 238Pu production.","PeriodicalId":400400,"journal":{"name":"Frontiers in Nuclear Engineering","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127202421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unexpected features in the optical vibrational spectra of δ-UO3","authors":"T. Spano, A. Shields, J. Niedziela, A. Miskowiec","doi":"10.3389/fnuen.2022.995292","DOIUrl":"https://doi.org/10.3389/fnuen.2022.995292","url":null,"abstract":"Uranium trioxide displays a complex chemical phase space, with at least six structurally distinct polymorphs accessible via different synthetic routes. Remarkably, despite its technological importance, full structural and electronic characterization of these polymorphs remains an open area of study. δ-UO3 in particular has attracted significant theoretical attention due to its high point group and space group symmetries, having U (VI) in octahedral coordination with polyhedra interconnected through corner-sharing to build a 3-D cubic lattice with space group symmetry Pm-3m and Z = 1. Critical experimental information, such as its optical vibrational spectra, are not known. Here, we study the Raman and infrared (IR) spectra of δ-UO3 together with the support of density functional theory (DFT) calculations for spectral interpretation. A symmetry analysis of the DFT-predicted phonon eigenmodes indicates that δ-UO3 should have two IR active modes and no Raman active modes. Experimental results, however, indicate significant Raman scattering from δ-UO3. We therefore propose four potential explanations for this apparent contradiction: a possible tetragonal distortion to the cubic cell, the existence of a surface impurity layer, vacancy scattering, and structural activation of Raman signal. We use powder X-ray diffraction and confocal Raman spectroscopy with depth profiling to investigate these possibilities and suggest future experiments to explore this phenomenon in more detail. Understanding the lattice dynamics of δ-UO3 is important for identification of technogenic U phases via Raman and infrared spectroscopy and our results indicate that the simple understanding of δ-UO3 as a high-symmetry cubic structure should be reconsidered.","PeriodicalId":400400,"journal":{"name":"Frontiers in Nuclear Engineering","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131550427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hybrid parallel strategies for the neutron transport code PANDAS-MOC","authors":"Shunjiang Tao, Yunlin Xu","doi":"10.3389/fnuen.2022.1002951","DOIUrl":"https://doi.org/10.3389/fnuen.2022.1002951","url":null,"abstract":"PANDAS-MOC (Purdue Advanced Neutronics Design and Analysis System with Methods of Characteristics) is being developed to find high fidelity 3D solutions for steady state and transient neutron transport analysis. However, solving such transport problems in a large reactor core could be extremely computationally intensive and memory demanding. Because parallel computing is capable of improving computing efficiency and decreasing memory requirements, three parallel models of PANDAS-MOC are designed using the distributed memory and share memory architectures in this article: a pure message passing interface (MPI) parallel model (PMPI), a segment OpenMP threading hybrid model (SGP), and a whole-code OpenMP threading hybrid model (WCP). Their parallel performances are examined by the C5G7 3D core. For the measured speedup, PMPI model > WCP model > SGP model. The memory consumed by the WCP model is about 60% of that consumed by the PMPI model. This study also demonstrated that the performance of WCP parallelism is limited by the hybrid reduction in the CMFD calculation and omp atomic clause in the MOC sweep. Once they are optimized, the WCP model can outperform the PMPI model.","PeriodicalId":400400,"journal":{"name":"Frontiers in Nuclear Engineering","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116387509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Parallel schedules for MOC sweep in the neutron transport code PANDAS-MOC","authors":"Shunjiang Tao, Yunlin Xu","doi":"10.3389/fnuen.2022.1002862","DOIUrl":"https://doi.org/10.3389/fnuen.2022.1002862","url":null,"abstract":"Method of characteristics (MOC) is a commonly applied technique for solving the Boltzmann form of the neutron transport equation. In the PANDAS-MOC neutron transport code, MOC is used to determine the 2D radial solution. However, in the whole-code OpenMP threading hybrid model (WCP) of PANDAS-MOC, it is found that when using the classic parallelism, the MOC sweeping performance is restricted by the overhead incurred by the unbalanced workload and omp atomic clause. This article describes three parallel algorithms for the MOC sweep in the WCP model: the long-track schedule, equal-segment schedule, and no-atomic schedule. All algorithms are accomplished by updating the partition approach and rearranging the sweeping order of the characteristic rays, and their parallel performances are examined by the C5G7 3D core. The results illustrate that the no-atomic schedule can reach 0.686 parallel efficiency when using 36 threads, which is larger than the parallel efficiency obtained in the MPI-only parallelization model.","PeriodicalId":400400,"journal":{"name":"Frontiers in Nuclear Engineering","volume":"256 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121233787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Uptake of selected organic ligands by hardened cement paste: Studies on proxy ligands for the degradation of polyacrylonitrile and general considerations on the role of different functionalities in the uptake process","authors":"Péter G. N. Szabó, A. Tasi, X. Gaona, A. Maier, S. Hedström, M. Altmaier, H. Geckeis","doi":"10.3389/fnuen.2022.997398","DOIUrl":"https://doi.org/10.3389/fnuen.2022.997398","url":null,"abstract":"The uptake of α-hydroxyisobutyric acid (HIBA), 3-hydroxybutyric acid (HBA) and glutaric acid (GTA) by hardened cement paste (HCP) in the degradation stage II was investigated at various ligand concentrations (10−7 M ≤ [L]tot ≤ 0.1 M) and solid-to-liquid ratios (0.2 g⋅dm−3 ≤ S:L ≤ 50 g⋅dm−3). These organic ligands were previously identified as representative of the main degradation products of UP2W, a polyacrylonitrile-based material used as filter aid in nuclear power plants, under repository conditions. Sorption experiments were conducted with inactive (HIBA, HBA, GTA) and active (14C-labelled GTA) organic ligands. Sorption experiments show a weak uptake of HIBA and HBA by HCP, with distribution coefficients determined as Rd (HIBA) = (2.2 ± 1.3)⋅10−3 m3⋅kg−1 and Rd (HBA) = (1.6 ± 0.8)⋅10−3 m3⋅kg−1. A stronger uptake is observed for GTA, i.e. Rd (GTA) = (1.3 ± 0.5)⋅10−2 m3⋅kg−1, likely reflecting the contribution from the ligand’s second carboxylate group. GTA follows a linear sorption behaviour within 10−7 M ≤ [GTA]tot ≤ 0.1 M, which was successfully modelled with a one-site Langmuir isotherm. The adsorption capacity determined for the uptake of GTA by HCP is slightly higher but in line with the capacity previously reported for isosaccharinic acid (ISA), whereas the affinity constant derived for GTA is significantly lower than values reported for stronger binding sites in HCP for the uptake of ISA. HIBA and HBA have a minor impact on the surface charge of HCP up to [L]tot ≈ 0.1 M. On the contrary, GTA induces a clear decrease in the surface charge above [GTA]tot ≈ 10−3 M resulting in an isoelectric point at [GTA]tot ≈ 6⋅10−2 M. Comparison of sorption data obtained in this work and reported in the literature for organic ligands containing the functional groups -COOH and -OH underlines the key role of multiple functionalities as a factor strengthening the interaction with the HCP surface. The participation of alcohol groups is particularly strong when present in their deprotonated state. These results provide information to quantitatively assess the uptake by HCP of organic ligands relevant in the context of nuclear waste disposal, and to understand their impact on the surface properties of cement.","PeriodicalId":400400,"journal":{"name":"Frontiers in Nuclear Engineering","volume":"120 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128034406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A computational pipeline to generate a synthetic dataset of metal ion sorption to oxides for AI/ML exploration","authors":"Chunhui Li, P. Zarzycki","doi":"10.3389/fnuen.2022.977743","DOIUrl":"https://doi.org/10.3389/fnuen.2022.977743","url":null,"abstract":"The charged mineral/electrolyte interfaces are ubiquitous in the surface and subsurface–including the surroundings of the geological disposal sites for radioactive waste. Therefore, understanding how ions interact with charged surfaces is critically important for predicting radionuclide mobility in the case of waste leakage. At present, the Surface Complexation Models (SCMs) are the most successful thermodynamic frameworks to describe ion retention by mineral surfaces. SCMs are interfacial speciation models that account for the effect of the electric field generated by charged surfaces on sorption equilibria. These models have been successfully used to analyze and interpret a broad range of experimental observations including potentiometric and electrokinetic titrations or spectroscopy. Unfortunately, many of the current procedures to solve and fit SCM to experimental data are not optimal, which leads to a non-transferable or non-unique description of interfacial electrostatics and consequently of the strength and extent of ion retention by mineral surfaces. Recent developments in Artificial Intelligence (AI) offer a new avenue to replace SCM solvers and fitting algorithms with trained AI surrogates. Unfortunately, there is a lack of a standardized dataset covering a wide range of SCM parameter values available for AI exploration and training–a gap filled by this study. Here, we described the computational pipeline to generate synthetic SCM data and discussed approaches to transform this dataset into AI-learnable input. First, we used this pipeline to generate a synthetic dataset of electrostatic properties for a broad range of the prototypical oxide/electrolyte interfaces. The next step is to extend this dataset to include complex radionuclide sorption and complexation, and finally, to provide trained AI architectures able to infer SCMs parameter values rapidly from experimental data. Here, we illustrated the AI-surrogate development using the ensemble learning algorithms, such as Random Forest and Gradient Boosting. These surrogate models allow a rapid prediction of the SCM model parameters, do not rely on an initial guess, and guarantee convergence in all cases.","PeriodicalId":400400,"journal":{"name":"Frontiers in Nuclear Engineering","volume":"288 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134089319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}