bluuebunny/crossref_metadata_2025 huggingface dataset:
Passive eDNA collection enhances aquatic biodiversity analysis
Authors: Bessey Cindy , Neil Jarman Simon , Simpson Tiffany , Miller Haylea , Stewart Todd , Kenneth Keesing John , Berry Oliver
Published: February 2021

Environmental DNA (eDNA) metabarcoding is a sensitive and widely used approach for species detection and biodiversity assessment. The most common eDNA collection method in aquatic systems is actively filtering water through a membrane, which is time consuming and requires specialized equipment. Ecological studies investigating species abundance or distribution often require more samples than can be practically collected with current filtration methods. Here we demonstrate how eDNA can be passively collected in both tropical and temperate marine systems by directly submerging filter membranes (positively charged nylon and non-charged cellulose ester) in the water column. Using a universal fish metabarcoding assay, we show that passive eDNA collection can detect fish as effectively as active eDNA filtration methods in temperate systems and can also provide similar estimates of total fish biodiversity. Furthermore, passive eDNA collection enables greater levels of biological sampling, which increases the range of ecological questions that eDNA metabarcoding can address.
Size-control in the synthesis of oxo-bridged phosphazane macrocycles via a modular addition approach
Authors: Shi Xiaoyan , León Felix , Ong How Chee , Ganguly Rakesh , Díaz Jesús , García Felipe
Published: February 2021

Inorganic macrocycles remain largely underdeveloped compared with their organic counterparts due to the challenges involved in their synthesis. Among them, cyclodiphosphazane macrocycles have shown to be promising candidates for supramolecular chemistry applications due to their ability to encapsulate small molecules or ions within their cavities. However, further developments have been handicapped by the lack of synthetic routes to high-order cyclodiphosphazane macrocycles. Moreover, current approaches allow little control over the size of the macrocycles formed. Here we report the synthesis of high-order oxygen-bridged phosphazane macrocycles via a “3 + n cyclisation” (n = 1 and 3). Using this method, an all-PIII high-order hexameric cyclodiphosphazane macrocycle was isolated, displaying a larger macrocyclic cavity than comparable organic crown-ethers. Our approach demonstrates that increasing building block complexity enables precise control over macrocycle size, which will not only generate future developments in both the phosphazane and main group chemistry but also in the fields of supramolecular chemistry.
The role of poly(2-alkyl-2-oxazoline)s in hydrogels and biofabrication
Authors: Trachsel Lucca , Zenobi-Wong Marcy , Benetti Edmondo M.
Published: February 2021

Poly(2-alkyl-2-oxazoline)s (PAOXAs) have been rapidly emerging as starting materials in the design of tissue engineering supports and for the generation of platforms for cell cultures, especially in the form of hydrogels.
Natural Trojan horse inhibitors of aminoacyl-tRNA synthetases
Authors: Travin Dmitrii Y. , Severinov Konstantin , Dubiley Svetlana
Published: February 2021

The structures, biosynthesis, and modes of action of albomycin, microcin C and agrocin 84, antibiotics targeting aminoacyl-tRNA synthetases, are reviewed. Using bioinformatics several new putative aminoacyl-tRNA synthetase inhibitors are predicted.
Chemisorbed oxygen or surface oxides steer the selectivity in Pd electrocatalytic propene oxidation observed by operando Pd L-edge X-ray absorption spectroscopy
Authors: Koroidov Sergey , Winiwarter Anna , Diaz-Morales Oscar , Görlin Mikaela , Halldin Stenlid Joakim , Wang Hsin-Yi , Börner Mia , Goodwin Christopher Matthew , Soldemo Markus , Pettersson Lars Gunnar Moody , Rossmeisl Jan , Hansson Tony , Chorkendorff Ib , Nilsson Anders
Published: February 2021

Operando Pd X-ray absorption spectroscopy elucidates how the surface oxygen species steer the selectivity in the electrochemical oxidation of propene.
Sample dependent performance of aqueous copper hexacyanoferrate/zinc batteries
Authors: Kjeldgaard Solveig , Wagemaker Marnix , Iversen Bo Brummerstedt , Bentien Anders
Published: February 2021

The performance of aqueous CuHCF/Zn batteries are highly dependent on the CuHCF sample. With Na-based electrolyte the capacity retention improves at low pH, whereas cells with Zn-based electrolyte have similar performance at pH 2 and pH 4.
Protein-, polymer-, and silica-based luminescent nanomaterial probes for super resolution microscopy: a review
Authors: Thompson S. , Pappas Dimitri
Published: February 2021

Super resolution microscopy was developed to overcome the Abbe diffraction limit, which effects conventional optical microscopy, in order to study the smaller components of biological systems.
Tuning morphology, surface, and nanocrystallinity of rare earth vanadates by one-pot colloidal conversion of hydroxycarbonates
Authors: Guida Gabriela , Huband Steven , Walker Marc , Walton Richard I. , de Sousa Filho Paulo C.
Published: February 2021

The mechanisms of a one-pot colloidal conversion of hydroxycarbonate templates into vanadate nanoparticles were investigated, with further correlation of Eu3+ spectroscopic properties to particle size, texture, nanocrystallinity, and defect density.
Influence of interaction between surface-modified magnetic nanoparticles with infectious biofilm components in artificial channel digging and biofilm eradication by antibiotics in vitro and in vivo
Authors: Quan Kecheng , Jiang Guimei , Liu Jian , Zhang Zexin , Ren Yijin , Busscher Henk J. , van der Mei Henny C. , Peterson Brandon W.
Published: February 2021

Artificial channels dug by non-interacting nanoparticles in infectious biofilms enhance antibiotic penetration and bacterial killing in vitro and in vivo.
Potential therapeutic targets and molecular details of anthocyan-treated inflammatory bowel disease: a systematic bioinformatics analysis of network pharmacology
Authors: Lin Yuqi , Luo Lianxiang , Lin Haowen , Li Xiaoling , Huang Riming
Published: February 2021

Anthocyans, containing anthocyanins and anthocyanidins, play a crucial role in preventing and treating inflammatory bowel disease (IBD).
Orderly aligned manganese-based nanotube arrays with controllable secondary structures
Authors: Huang Xiaoyan , Liang Zhuoxi , Wen Jiqiu , Liu Yong , Taallah Ayoub , Yao Xin , Zhang Zhiyou , Yu Tian , Zhang Sijie
Published: February 2021

The collaboration of nanochannel confinement and dynamic negative growth creates orderly aligned manganese-based nanotube arrays decorated with nanopores as a secondary structure.
Synthesis and spectral characterization of the first fluorescein-tagged iron(ii) clathrochelates, their supramolecular interactions with globular proteins, and cellular uptake
Authors: Selin Roman O. , Klemt Insa , Chernii Viktor Ya. , Losytskyy Mykhaylo Yu. , Chernii Svitlana , Mular Andrzej , Gumienna-Kontecka Elzbieta , Kovalska Vladyslava B. , Voloshin Yan Z. , Vologzhanina Anna V. , Dorovatovskii Pavel V. , Mokhir Andriy
Published: February 2021

The fluorescein-tagged iron(ii) clathrochelate was synthesized for the first time and its accumulation in A2780 cancer cells was studied.
Concepts for flow chemistry with whole-cell biocatalysts
Authors: Adebar Niklas , Nastke Alina , Gröger Harald
Published: February 2021

By combining continuous flow processing and biocatalysis, efficient, stable and cost-effective processes can be realised. In this review, an overview about different concepts for continuous flow processes based on the use of whole-cells as catalysts is given.
Thermodiffusion anisotropy under a magnetic field in ionic liquid-based ferrofluids
Authors: Fiuza T. , Sarkar M. , Riedl J. C. , Cēbers A. , Cousin F. , Demouchy G. , Depeyrot J. , Dubois E. , Gélébart F. , Mériguet G. , Perzynski R. , Peyre V.
Published: February 2021

Ferrofluids based on maghemite nanoparticles (NPs), typically 10 nm in diameter, are dispersed in an ionic liquid (1-ethyl 3-methylimidazolium bistriflimide – EMIM-TFSI).
An oligopeptide/aptamer-conjugated dendrimer-based nanocarrier for dual-targeting delivery to bone
Authors: Ren Mingxing , Li Yuzhou , Zhang He , Li Lingjie , He Ping , Ji Ping , Yang Sheng
Published: February 2021

The CH6-PAMAM-C11 dual-targeting nanocarrier can better deliver drugs to sites of osteoblast activity in vivo.
Negligible concentration quenching in photoluminescent nanocrystals with high photoactive rare-earth concentrations: silica–(Tb,Ce)PO4 transparent glass-ceramic green phosphors
Authors: Iwasaki Rena , Kajihara Koichi
Published: February 2021

In silica–(Tb,Ce)PO4 transparent glass-ceramic green phosphors, the elimination of quenching centers achieved negligible concentration quenching coexisting with rapid energy migration in nanocrystals with high photoactive rare-earth concentrations.
Tailoring nitric oxide release with additive manufacturing to create antimicrobial surfaces
Authors: Chug Manjyot Kaur , Bachtiar Emilio , Narwold Nicholas , Gall Ken , Brisbois Elizabeth J.
Published: February 2021

A facile and inexpensive method to impregnate the NO donor (SNAP, S-nitroso-N-acetylpenicillamine) in 3D-printed medical devices to resist infection. The NO-release levels from the surfaces can be modulated by tuning the porosities of the surfaces.
Porous intermetallic Ni2XAl (X = Ti or Zr) nanoparticles prepared from oxide precursors
Authors: Kobayashi Yasukazu , Tada Shohei , Kikuchi Ryuji
Published: February 2021

Chemical synthesis of porous intermetallic Ni2XAl (X = Ti or Zr) nanoparticles with small crystal size (24–34 nm) and high surface area (10–71 m2 g−1).
Visible-light-induced silylation: an update
Authors: Ghosh Sumit , Lai Dipti , Hajra Alakananda
Published: February 2021

This review summarizes the recent findings and developments in the emerging area of photocatalytic silylation with literature coverage mainly extending from 2014 to February 2021.
Recent advances in PM6:Y6-based organic solar cells
Authors: Guo Qing , Guo Qiang , Geng Yanfang , Tang Ailing , Zhang Maojie , Du Mengzhen , Sun Xiangnan , Zhou Erjun
Published: February 2021

This review provides a detailed overview of PM6:Y6-based organic solar cells (OSCs), including the underlying mechanisms, terpolymers derived from PM6, ternary or quaternary OSCs, interfacial engineering and electrode progress.
MnO2-based nanostructured materials for various energy applications
Authors: Kwon Nam Hee , Lee Kang-Gyu , Kim Hyun Kyu , Hwang Seong-Ju
Published: February 2021

In this review, recent research activities devoted to nanostructured MnO2-based electrocatalyst/electrode materials are systematically surveyed along with versatile synthetic methods and chemical strategies for optimizing their functionalities.
Retraction: The synthesis and biological activity of marine alkaloid derivatives and analogues
Authors: Zhou Shiyang , Huang Gangliang
Published: February 2021

Retraction of ‘The synthesis and biological activity of marine alkaloid derivatives and analogues’ by Shiyang Zhou et al., RSC Adv., 2020, 10, 31909–31935, DOI: 10.1039/D0RA05856D.
A novel protection scheme for VSC‐HVDC transmission lines based on current integral autocorrelation
Authors: Wu Chuanjian , Zhang Dahai , Luo Guomin , Li Meng , He Jinghan
Published: February 2021

Voltage source converter‐based high voltage direct current (VSC‐HVDC) transmission system has become the mainstream of power construction and plays an increasingly important role in the power system. However, the DC line fault results in shutting down of the converters, which can greatly endanger the security of the power grid. So it is essential to find a fast fault identification strategy for DC line protection technology. In addition, the existing backup protection scheme has the problems of long delay and strict communication synchronisation requirements. Therefore, this study proposes a novel protection scheme for VSC‐HVDC transmission lines based on the fault current integral autocorrelation coefficient. The fault current and fault current frequency characteristics of VSC‐HVDC transmission lines are analysed first. Second, this study proposes a method to filter out distributed capacitance current by current integration and eliminate the oscillation of fault current. Finally, the difference of the current integral during different faults (internal or external fault) is analysed, and the autocorrelation coefficient is introduced to express the difference. Hence, this study proposes a new principle for identifying faults using the autocorrelation coefficient of the fault current integral. Simulation results show that the protection principle is not affected by the distributed capacitive current and does not require strict communication synchronisation. It has an excellent performance in intolerance to fault resistance and noise interference and can be used as backup protection for VSC‐HVDC transmission system.
Regulating dielectric performances of Poly(vinylidene fluoride) nanocomposites by individually controlling shell thickness of Core@Double‐Shells structured nanowires
Authors: Yang Minhao , Xue Zhi‐Yong , Dang Zhi‐Min , Shen Yang , Haghi‐Ashtiani Paul , He Delong , Xu Jian , Bai Jinbo
Published: February 2021

The synthesis of core@double‐shells structured TiO2@C@SiO2 nanowires (NWs) with variable thickness of carbon inner shell and SiO2 outer shell was achieved by individually controlling the chemical vapour deposition time and amount of silicon precursor added in the sol–gel synthesis. The resultant TiO2@C@SiO2 NWs filled nanocomposites exhibited an excellent dielectric performance with simultaneously improved dielectric constant and suppressed dielectric loss, which could be further regulated by individually controlling the carbon inner shell and SiO2 outer shell thickness. More importantly, the influences of the conductive carbon inner shell and insulated SiO2 outer shell thickness on the dielectric performance of nanocomposites were clearly revealed. The increase of the conductive carbon inner shell thickness would lead to an increase in dielectric constant and loss of nanocomposites, while the insulated SiO2 outer shell exhibited a totally opposite law that the dielectric constant and loss of nanocomposites decrease with increasing SiO2 outer shell thickness. Numerical simulations were also carried out to theoretically verify the relationship between the dielectric loss and SiO2 outer shell thickness. This promising controllable multi‐shell structure could be extended to a variety of hybrids to develop high‐performance dielectric nanocomposites.
A novel classification model of collective user web behaviour based on network traffic contents
Authors: Liu Hongri , Wang Shuo , Wei Yuliang , Wang Bailing
Published: February 2021

Web behaviour analysis of a collective user has provided a powerful means for studying the collective user interests on the Internet. However, the existing research merely analyses the behaviour of a single user who accesses multiple applications or multiple users who access one application. The authors propose a web behaviour classification model for collective user, in which the title fields in HTTP flows are extracted from the mirrored network traffic that has been already captured for any given period of time. The title fields, considered as the short abstract of the whole web pages browsed by the users, are vectorized by natural language processing technologies. Specifically, the Latent Dirichlet allocation (LDA) algorithm is used to calculate the topic distribution probability matrix. Afterward, the multi‐class classifiers are trained and tested using the manually labelled probability distribution matrix from the output of the LDA algorithm to classify the user behaviour topics. The experiments demonstrate that the highest classification accuracy of the model reaches 81.2% by combing the LDA algorithm with Random Forest classifiers under the classification model.
Analysing digital predistortion technique for computation‐efficient power amplifier linearisation in the presence of measurement noise
Authors: Tripathi Girish Chandra , Rawat Meenakshi
Published: February 2021

The noise is an inherent part of a transceiver system, which becomes more severe on low‐cost systems. The power amplifier (PA) further enhances this noise and the signal to be propagated to the receiver. The conventional approach of digital predistortion (DPD) assumes an ideal transceiver system while extracting data for the predistortion function generation. As a result, performance limitation arises due to residual signal–noise interaction. This study presents the accuracy and implementation issues of DPD on a low‐cost transceiver having lower bit resolution in the presence of transceiver noise. Different model architectures, as well as processing algorithms, are compared in terms of numerical stability of the solution (condition number of observation matrix), efficient field‐programmable gate array (FPGA) implementation (dispersion of coefficients, in‐band model performance (normalised mean square error), and out‐of‐band model performance (adjacent channel power ratio). The simulation results are tested on FPGA and direct conversion transceiver‐based platform using PA. A long‐term evolution signal with 64 quadrature amplitude modulation is used for performance evaluation. The suitability of the various polynomial models for fixed‐point implementation and the required memory size for implementing the DPD model is further established.
Smooth particle filter‐based likelihood approximations for remaining useful life prediction of Lithium‐ion batteries
Authors: El‐Dalahmeh Mo'ath , Al‐Greer Maher , El‐Dalahmeh Ma'd , Short Michael
Published: February 2021

Accurate prediction of the remaining useful life (RUL) in Lithium‐ion batteries (LiBs) is a key aspect of managing its health, in order to promote reliable and secure systems, and to reduce the need for unscheduled maintenance and costs. Recent work on RUL prediction has largely focused on refining the accuracy and reliability of the RUL prediction. The author introduces a new online RUL prediction for LiB using smooth particle filter (SPF)‐ based likelihood approximation method. The proposed algorithm can accurately estimate the unknown degradation model parameters and predict the degradation state by solving the optimisation problem at each iteration, rather than only taking a gradient step, that tends to lead to rapid convergence, avoids instability issues and improves predictive accuracy. From the experimental datasets published by Prognostics Centre of Excellence (PCoE) of NASA, a second order degradation model was created to explore the degradation of LiB, utilising non‐linear characteristics and non‐Gaussian capacity degradation. RUL prediction was tested with various predicted starting points to assess whether the amount of data and parameters' uncertainty influenced the accuracy of the prediction. Results show that the proposed prediction approach gives improved prediction accuracy and improves the convergence rate in comparison with the particle filter (PF) and other methods such as unscented particle filter (UPF). Since the maximum error of the SPF predicting approach is relatively small, RUL prediction in the best case at the prediction starting point consisting of 80 cycles is 127 cycles. The prediction relative error was approximately 0.024, and the absolute error of the proposed algorithm is around 2 cycles, which is lower than the PF (around 16 cycles). RUL prediction is close to 108 cycles and relative error is around 0.136, while the absolute error prediction is approximately 16.
Optimal allocation of protection and control devices in smart distribution systems: Models, methods, and future research
Authors: Georgilakis Pavlos S. , Arsoniadis Charalampos , Apostolopoulos Christos A. , Nikolaidis Vassilis C.
Published: February 2021

The fundamental goal of the distribution system operator (DSO) is to serve its customers with reliable and low‐cost electricity. Failures in power distribution systems are responsible for 80% of customer service interruptions. The emergence of smart distribution system (SDS) with advanced distribution automation (DA) and communication infrastructure offers a great opportunity to improve reliability, through the automation of fault location, isolation, and service restoration (FLISR) process. DA includes the installation of protection and control devices (PCD). The use of PCD makes fault management more efficient, reduces average outage duration per customer in case of faults, reduces costs due to unsupplied energy, and improves distribution system reliability. Although the use of PCD remarkably enhances distribution system reliability, it is neither economical nor affordable to install them in all potential locations. To obtain the optimal allocation of PCD (OAPCD), an optimisation problem has to be formulated and solved. Several models and methods have been suggested for the OAPCD in SDSs. Herein, an overview of the state‐of‐the‐art models and methods applied to the OAPCD in SDSs are introduced, identifying the contributions of reviewed works, identifying advantages and disadvantages, classifying and analysing current and future research directions in this area.
SMALL MODULAR PWR DESIGN FOR TRU RECYCLING WITH McCARD-MASTER TWO-STEP PROCEDURE
Authors: Hwang Dae Hee , Hong Ser Gi
Published: February 2021

In our previous study, a small modular PWR core was designed for TRU (Transuranics) recycling with multi-recycling scheme with a typical two-step procedure using DeCART2D/MASTER code system in which the lattice analysis for producing homogenized group constant was performed by DeCART2D while whole core analysis was conducted by MASTER code. However, the neutron spectrum hardening of the LWR core loaded with TRU requires validating the multi-group cross section library and resonance self-shielding treatment method in lattice calculation. In this study, a new procedure using McCARD/MASTER was used to analyze the SMR core, in which the lattice calculation was performed by a Monte Carlo code called McCARD with a continuous energy library to generate homogenized two-group assembly cross sections. The SMR core analysis was performed to show neutronic characteristics and TRU mass flow in the SMR core with TRU multi-recycling. The result shows that the analyses on the neutronic characteristics and TRU mass flow using the McCARD/MASTER code system showed good agreement with the previous ones using the DeCART2D/MASTER code system. The neutronic characteristics of each cycle of the core satisfied the typical limit of a commercial PWR core and the SMR core consumes effectively TRU with net TRU consumption rates of 8.46~14.33 %.
CORE DESIGN OF BREED & BURN MOLTEN SALT FAST REACTOR
Authors: Cuoc Eduardo , Shwageraus Eugene , Kasam Alisha , Scott Ian
Published: February 2021

Previous designs of once-through solid-fuelled breed-and-burn (B&B) reactor and the conventional molten salt reactor (MSR) concepts suffer from material limitation of neutron irradiation damage and chemical corrosion. A novel breed-and-burn molten salt reactor (BBMSR) concept uses separate molten salt fuel and coolant in a linear assembly core configuration. Similar to Moltex Energy Stable Salt Reactor (SSR) design, the configuration with fuel salt contained in fuel tubes and coolant salt in pool type reactor vessel has been previously studied. The study confirmed that breed-and-burn operation is feasible in principle, however with a low neutronic margin. The objective of this paper was to seek improvements of the neutronic margin with a metallic natural uranium blanket design. A parametric study was performed for the natural uranium blanket design. BBMSR neutronic performance simulation was modelled using Serpent, a Monte Carlo reactor physics code, with a single 3D hexagonal channel containing a single fuel tube in an infinite lattice with reflective radial and vacuum axial boundary conditions. The addition of a metallic natural uranium blanket inside the fuel tube, which increases the natural uranium metal to fuel salt ratio (ϒ) of the BBMSR, was shown to significantly increase the neutronic performance of the BBMSR.
FUEL TAP: A SIMPLIFIED BREED AND BURN MSR
Authors: de Oliveira Rodrigo G.G. , Hombourger Boris A.
Published: February 2021

Breed-and-burn Molten Salt Reactors are an interesting option of reactor design that allow high fuel utilization while operating on an open fuel cycle. Such reactors usually require specialized codes in order to model its fuel cycle and the flowing fuel in an unmoderated core. In this work, we propose a design and perform a preliminary analysis of a homogeneous chloride salt single-fluid design. The fuel cycle is analyzed using the EQL0D tool in order to model reactor start-up and transition into an equilibrium state. Core simulation is performed using ATARI, an OpenFOAM-based multiphysics code developed at PSI. Results show that the core size for such a reactor is quite big and that it can be easily started with high-assay LEU. In addition, the core has been designed to promote a quasi-1D flow, opening the possibility of modeling the core with legacy codes in the future.
CORE DESIGN ACTIVITIES OF THE VERSATILE TEST REACTOR – CONCEPTUAL PHASE
Authors: Heidet F. , Roglans-Ribas J.
Published: February 2021

The Versatile Test Reactor (VTR) is a new fast spectrum test reactor being developed in the United States under the direction of the US Department of Energy, Office of Nuclear Energy. The VTR mission is to enable accelerated testing of advanced reactor fuels and materials required for advanced reactor technologies. This includes neutron irradiation capabilities which would support alternate coolants including molten salt, lead/lead-bismuth eutectic mixture, gas, and sodium. The VTR aims at addressing most of the needs of the various stakeholders, which is primarily composed of advanced reactor technologists, developers and vendors, as well as a number of others interested parties.

Design activities are underway targeting a first criticality date by 2026, with General Electric recently joining the project to contribute to the VTR plant design. Current efforts are focused on all aspects of the VTR design, with the core design being at the center of the initial steps. The VTR is currently proposed as a 300 MWth sodium-cooled fast reactor able to reach peak fast flux levels in excess of 4.0x1015 n/cm2-s (and total flux level of about 6.0x1015 n/cm2-s). In this configuration, it is using ternary metallic fuel with reactor-grade plutonium and 5% low-enriched uranium.
NEUTRONICS ANALYSIS OF VVER-1000 CORE USING AT-FCM FUEL
Authors: Ghazanfar Mahmood Ahmad , Kan Wang
Published: February 2021

Using the Fully Ceramic Microencapsulated (FCM) fuel in light water reactors has multiple advantages, as it is accident tolerant because of; no hydrogen generation due to the cladding interaction with steam at high temperature, better retention of fission fragments and proliferation resistant due to very small production of transuranic elements during the burnup as compared to the standard UO2 fuel. In this study neutronics analysis of AT-FCM fuel consisting of TRISO particles embedded in SiC matrix is performed for replacement in existing VVER-1000 reactors. Standard VVER-1000 fuel assembly is transformed to Accident Tolerant Fully Ceramic Microencapsulated (AT-FCM) fuel assembly based on hydraulic diameter of the VVER-1000 assembly, the number of fuel pins are decreased with increased diameter and enrichment to conserve the initial fissile loading in AT-FCM assembly. Fuel centerline temperature of the AT-FCM assembly is found to be lower than the reference UO2 fuel assembly at the same total power produced because of the much higher thermal conductivity. FCM-TRISO fuel assembly namely Array 15 with 169 pins is proposed and analyzed. Pin cell, assembly level and full core calculations have been performed with SERPENT code using implicit and explicit models. VVER-1000 full core is modelled using the transformed FCM assembly. The embedded TRISO particles in a SiC matrix and the use of FeCrAl cladding turns out to be the perfect case for accident tolerance. High burnup of AT-FCM core in terms of MWd/kgHM for the same number of EFPDs is observed as compared to reference UO2 core due to the small breeding of transuranic elements Pu-239, Pu-240 and Pu-241. Appreciable quantity of the power is produced due to the fission of transuranic elements in reference UO2 assembly so the burnup in MWd/kgHM remains smaller than the AT-FCM fuel. Comparatively more softening of spectrum is found in AT-FCM fuel cells and assemblies towards the middle of the cycle (MOC) and End of the Cycle (EOC), this softening of spectrum tends to increase the rate of U-235 depletion. Very small quantities of plutonium isotopes are produced in AT-FCM as compared to the reference UO2 assembly because of small loading of U-238 at the BOC. The neutronics performance of AT-FCM core with burnable poison consisting of Gd2O3 and Er2O3 turn out to be better than reference UO2 assembly as it exhibits smooth burnup. Fuel Temperature Coefficient (FTC) and Moderator Temperature Coefficient (MTC) of the AT-FCM assembly is negative for most part of the cycle however, towards the end of cycle it becomes less negative due to small quantities of resonance absorbers, softening of thermal flux and increased rate of fission absorption in UO2.
A SIMPLIFIED TWO-NODE COARSE-MESH FINITE DIFFERENCE METHOD FOR PIN-WISE CALCULATION WITH SP3
Authors: Zhao Wenbo , Yu Yingrui , Chai Xiaoming , Ning Zhonghao , Zhang Bin , Cai Yun , Liu Kun , Peng Xingjie , Yu Junchong
Published: February 2021

For accurate and efficient pin-by-pin core calculation of SP3 equations, a simplified two-node Coarse Mesh Finite Difference (CMFD) method with the nonlinear iterative strategy is proposed. In this study, the two-node method is only used for discretization of Laplace operator of the 0th moment in the first equation, while the fine mesh finite difference (FMFD) is used for the 2nd moment flux and the second equation. In the two-node problem, transverse flux is expanded to second-order Legendre polynomials. In addition, the associated transverse leakage is approximated with flat distribution. Then the current coupling coefficients are updated in nonlinear iterations. The generalized eigenvalue problem from CMFD is solved using Jacobi-Davidson method. A protype code CORCA-PIN is developed. FMFD scheme is implemented in CORCA-PIN as well. The 2D KAIST 3A benchmark problem and extended 3D problem, which are cell homogenized problems with strong absorber, are tested. Numerical results show that the solution of the simplified two-node method with 1×1 mesh per cell has comparable accuracy of FMFD with 4×4 meshes per cell, but cost less time. The method is suitable for whole core pin-wise calculation.
PIN POWER CALCULATION SCHEME FOR REACTOR PRESSURE VESSEL FAST NEUTRON FLUENCE ESTIMATION
Authors: Brovchenko Mariya , Taforeau Julien
Published: February 2021

The estimation of the neutron fluence at the Reactor Pressure Vessel (RPV) is classically carried out by a two-step approach. The first step is to estimate the full core neutron source term whether the second step of the calculation consists in the transport of neutrons from the core (source term) to the RPV using the neutron fission distribution determined in the previous step. For this purpose, the neutron fission distribution is to be accurately determined at the fuel pin level for the assemblies on the border of the core. To achieve this goal, two methods are evaluated in this study. The first method considered is a full core 2D Monte Carlo calculation using the MNCP6 code. The second method is based on a deterministic approach using the CASMO5 multi-segment option, allowing a full 2D transport calculation at the pin level with an expected accuracy similar to a stochastic method. The comparison of the two methods shows an overall good agreement with differences within the statistical uncertainty for different cores: homogeneous UOX core, mixed UOX-MOX loading and the effect of the hafnium rods used in the assemblies in the periphery of the core. The modelling limitation and the associated calculational time are discussed for the comparison of the two approaches.
PROCESSING RESONANCE SELF-SHIELDING EFFECT OF GADOLINIA BASED ON IMPTOVED SUPERCELL SCHEME
Authors: Li Jikui , Zu Tiejun , Yin Wen , Cao Liangzhi
Published: February 2021

An improved supercell scheme has been proposed in this paper to efficiently and accurately process resonance self-shielding effect of gadolinia. Resonance effects are classified into global shadowing effect and local effects involving resonance interference, spatial self-shielding effects. Two categories of effects are decoupled and treated respectively based on different 1-D cylindrical pins. Hyperfine group method is applied to obtain multi-group cross sections for each 1-D pin. Afterwards, two categories of effects are coupled based on a correction formula. Because of the low efficiency for Carlvik method to compute collision probabilities in hyperfine group method, online tabulation and interpolation method is developed to accelerate gaining collision probabilities. The proposed scheme is verified against the problems of 3×3 pins with gadolinia rod, VERA 2O assembly with 12 gadolinia rods and VERA 2P with 24 gadolinia rods. The numerical results suggest promising consistence of multi-group cross sections and eigenvalues between the proposed scheme and reference solutions.
IMPLEMENTATION OF 2D/1D GAMMA TRANSPORT AND GAMMA HEATING CAPABILITY IN MPACT
Authors: Wang Xinyan , Liu Yuxuan , Martin William , Stimpson Shane
Published: February 2021

This paper presents the most recent progress on the development of gamma transport capability for the CASL neutronics code MPACT: (1) 3D gamma transport and (2) explicit gamma heating capabilities. The 3D gamma calculation capability was implemented by leveraging the 2D/1D solver originally developed for neutron calculations. The results were verified by MCNP6 on a small assembly with 5 × 5 pins. Generally, errors were lower than 0.5% on each axial mesh as long as MPACT was running with enough axial meshes. The gamma heating calculation considered the energy deposition from photoelectric absorption, Compton scattering, and pair production. Verification with MCNP6 for both 2D and 3D benchmarks showed that the errors of energy depositions are comparable with those of gamma fluxes, proving the proper implementation of the energy deposition.
AN INITIATIVE FOR THE DEVELOPMENT AND APPLICATION OF OPEN-SOURCE MULTI-PHYSICS SIMULATION IN SUPPORT OF R&D AND E&T IN NUCLEAR SCIENCE AND TECHNOLOGY
Authors: Fiorina C , Shriwise P , Dufresne A , Ragusa J , Ivanov K , Valentine T , Lindley B , Kelm S , Shwageraus E , Monti S , Batra C , Pautz A , Lorenzi S , Rubiolo P , Clifford I , Dechenaux B
Published: February 2021

Modelling and simulation (M&S) have gradually become irreplaceable tools in the field of Nuclear Science and Technology (NS&T), including nuclear energy systems. This is partly due to growing computational resources and advances in computational science and partly to the difficulties to finance, build and license new experimental facilities. However, the utilization of M&S for research and development (R&D) and education and training (E&T) applications is somewhat hampered by limited accessibility to controlled and sensitive nuclear M&S tools as well as by the desires of the developers of these tools to retain their intellectual property (IP). Open-source software and open-access data are growingly perceived as means to accelerate innovation by promoting synergistic collaborative developments while lowering the barriers associated to code distribution, modification, and sharing. Open-source software development is ideal for R&D and E&T purposes because it permits the enhancement of understanding, the use of advanced computational methods and it promotes the cooperation among researchers and scientists, without rigorous constraints on quality assurance or reliance on proprietary data for technology-specific validation. As a fundamental research tool, this helps to mitigate constraints related to dual use of such technology. It is in this context that an initiative is being launched under the aegis of the International Atomic Energy Agency (IAEA) to promote the development and application of open-source multi-physics simulation in support of R&D and E&T in NS&T. This paper presents scope and objectives of this initiative.
HIGH-ORDER FINITE ELEMENTS FOR THE NEUTRON TRANSPORT EQUATION ON HONEYCOMB MESHES
Authors: Calloo Ansar , Le Tellier Romain , Labeurthre David
Published: February 2021

Presently, APOLLO3®/MINARETsolves the transport equation using the multigroup Sn method with discontinuous finite elements on triangular meshes with Lagrange polynomial bases. The goal of this work is to solve the spatial problem on hexagonal geometries in the context of honeycomb lattice reactors, without further refining the computational mesh. The idea here is to construct high-order basis functions on the hexagonal element in order to improve the trade-off between computational cost and accuracy, in particular for multiphysics simulations where, often, thermalhydraulic modelling requires only assembly-average cross-sections to be defined (e.g.severe accident of fast breeder reactors)i.e.the assemblies are assumed homogeneous. One approach to achieve this goal is through the use of generalised barycentric functions such as the Wachspress rational functions. This research endeavour deals with the application of Wachspress rational functions to the neutron transport equation for hexagonal geometries up to order 3. With this method, it is possible to decrease the number of spatial unknowns required for the same accuracy, and thus the computational burden for complex geometries, such as honeycomb lattices is reduced.
DAPHNE-3D: A NEW TRANSPORT SOLVER FOR UNSTRUCTURED TETRAHEDRAL MESHES
Authors: Diamantopoulou Evangelia , Sciannandrone Daniele
Published: February 2021

A new Discrete Ordinates transport solver for unstructured tetrahedral meshes is presented. The solver uses the Discontinuous Galërkin Finite Element Method with linear or quadratic expansion of the flux within each cell. The solution of the one-group problem is obtained with non-preconditioned fixed-point or GMRES iterations. Precision and performances of the solver are evaluated on the 3D Radiation Transport Benchmark Problems proposed by Kobayashi, showing very good agreement with the reference and good computing times in serial execution.
K-MEANS CLUSTERING OF NEUTRON SPECTRA FOR CROSS SECTION COLLAPSE
Authors: Douglass Steven , Gibson Nathan
Published: February 2021

The process of generating cross sections for whole-core analysis typically involves collapsing cross sections against an approximate spectrum generated by solving problems with reduced scope (e.g., 2D slices of a fuel assembly). Such spectra vary with the location of a material region and with other state parameters (e.g., burnup, temperature, soluble boron concentration), resulting in a burdensome and potentially time consuming process to store and load spectra. Commonly, this is resolved by manually determinining material regions for which the cross sections can be collapsed with a single weighting flux, requiring a combination of domain knowledge, engineering judgment, and trial and error. Exploring new reactor concepts and solving increasingly complicated problems with deterministic transport methods will therefore benefit greatly from an automated approach to grouping spectra independent of problem geometry or reactor type. This paper leverages a data analytics technique known as k-means clustering to group regions with similar weighting spectra into individual clusters, within each of which an average weighting flux is applied. Despite the clustering algorithm being agnostic to the physics of the problem, the approach results in a nearly 98% decrease in number of spectra regions with minimal impact to the accuracy.
INTERPOLATION OF THE DILUTION GRID IN THE BENGAL CODE
Authors: Gibson Nathan A. , Douglass Steven J.
Published: February 2021

In the implementation of the equivalence-in-dilution self-shielding method, multigroup cross sections as a function of the background cross section (i.e., the dilution) are needed. The background cross section of a particular nuclide in a particular material is determined iteratively based on geometry and material composition, resulting in a large number of cross section look-ups and a continuously varying dilution as the independent variable. Typically, multigroup cross sections are interpolated based on a reference grid of a set of dilution values and corresponding cross sections. The selection of this grid and the interpolant used between the grid are not well-documented in the literature, and so the approach used by the Bengal code is of note to the technical community. This work compares the interpolation scheme of the legacy code TRANSX to a newly developed interpolation scheme based on cubic Hermite splines, both by looking at the relative error in generated cross sections and by assessing the impact on a simple reactor simulation.
A DEEP LEARNING BASED SURROGATE MODEL FOR ESTIMATING THE FLUX AND POWER DISTRIBUTION SOLVED BY DIFFUSION EQUATION
Authors: Zhang Qian , Zhang Jinchao , Liang Liang , Li Zhuo , Zhang Tengfei
Published: February 2021

A deep learning based surrogate model is proposed for replacing the conventional diffusion equation solver and predicting the flux and power distribution of the reactor core. Using the training data generated by the conventional diffusion equation solver, a special designed convolutional neural network inspired by the FCN (Fully Convolutional Network) is trained under the deep learning platform TensorFlow. Numerical results show that the deep learning based surrogate model is effective for estimating the flux and power distribution calculated by the diffusion method, which means it can be used for replacing the conventional diffusion equation solver with high efficiency boost.
DEVELOPMENT AND TESTING OF THE MODIFIED SIMPSON’S RULE FOR DISCRETE ORDINATES TRANSPORT APPLICATIONS
Authors: Hu Xiaoyu , Azmy Yousry Y.
Published: February 2021

A new angular quadrature type termed Modified Simpson Trapezoidal (MST) is developed based on the conventional Simpson’s 1/3 rule where the angular pattern over polar levels has a trapezoid shape. An adaptive coefficient correction scheme is developed to enable our new quadrature to integrate the angular flux over subintervals separated by the interior jump irregularities. A two-dimensional test problem is employed to verify the angular discretization error in the uncollided SN scalar flux computed with our new quadrature sets, as well as conventional angular quadrature types. Numerical results show that the MST quadrature error in the point-wise scalar flux converges with second order against increasing number of discrete angles, while the error obtained with other conventional quadrature types converges slower than first order depending on the regularity of the exact point-wise uncollided angular flux. In order to reduce the number of discrete points needed, a variant of the MST quadrature, namely MSTP30, is developed by using the Quadruple Range [1] polar quadrature with fixed 30 polar angles and applying the MST quadrature to the azimuthal dependence in each polar level. The angular discretization error in the point-wise SN scalar flux obtained with MSTP30 sets converges with fourth order because the polar discretization error is sufficiently reduced that MSTP30 behaves like a one-dimensional quadrature. Furthermore, because MSTP30 computes the integral over subintervals that keep the true solution’s irregularity at the boundaries, this fourth order convergence rate is unaffected by such inevitable irregularities.
ENHANCING THE PERFORMANCE OF FISSION SOURCE CONVERGENCE WITH FUNCTIONAL EXPANSION TALLIES IN SERPENT 2 MONTE CARLO CODE
Authors: Jambrina Ana , Leppänen Jaakko , Suikkanen Heikki
Published: February 2021

This paper presents an upgrade to the built-in response matrix based solver implemented in Serpent 2 Monte Carlo code aiming to improve the fission source convergence when obtaining the forward solution to the k-eigenvalue criticality source problems. The functional expansion tallies are introduced in an attempt to improve the accuracy of the cell-wise form factors that feed the response matrix solver, replacing the current mesh-based approach. The functional expansion tallies reconstruct the binning surface and collision tallies, by using high-order series expansion to represent the original and continuous spatial distributions. This new feature is implemented to Serpent 2 and tested by single-assembly and full-core PWR calculations (BEAVRS benchmark). The results show enhanced performance of the convergence acceleration methodology based on an improved initial guess of the fission source.
OPTIMISATION OF CRITICALITY AND BURNUP CALCULATIONS IN MONK®
Authors: Cox Andrew , Kyrieleis Albrecht , Powell-Gill Sam , Richards Simon , Tantillo Francesco
Published: February 2021

The primary goal of this paper is to increase the efficiency of criticality and burnup calculations in the ANSWERS MONK® Monte Carlo code [1]. Two ways of achieving this goal are investigated as part of the H2020 McSAFE Project: creating a unified energy grid for all materials in the model, and reducing the spread in variances of fluxes for depletable materials using a generated optimised importance map. The average tracking speedup factor across all cycles of all burnup calculations ran using the unified energy grid, at base temperature, was found to be 1.96. For criticality calculations at 400K with runtime Doppler broadening, the unified grid approach gave a total speedup factor of 7.32. This demonstrates the potential importance of this method to reduce the calculation time with models with runtime Doppler broadening. The use of the generated optimised importance map has been demonstrated to significantly reduce the variance in the standard deviations on the fluxes in the fuel pins across two different test cases. If a solution is required in which the standard deviation in none of the fuel pins exceeds 5% it was found that the number of scoring stages required was more than halved, highlighting the potential for the outlined methodology to speedup burnup credit calculations.
TOWARDS ZERO-VARIANCE SCHEMES FOR KINETIC MONTE-CARLO SIMULATIONS
Authors: Mancusi Davide , Zoia Andrea
Published: February 2021

The solution of the time-dependent transport problem for neutrons and precursors in a nuclear reactor is hard to treat in a naive Monte-Carlo framework because of the largely different time scales associated to the prompt-fission chains and to the decay of precursors. The increasing computer power and the development of variance-reduction techniques specific for reactor kinetics have recently unlocked the possibility to calculate reference solutions to the time-dependent transport problem. However, the application of time-dependent Monte Carlo to large systems (i.e., a full reactor core) is still stifled by the enormous computational requirements. In this paper, we formulate the construction of an optimal Monte-Carlo strategy (in the sense that it results in a zero-variance estimator) for a specific observable in time-dependent transport, in analogy with the existing schemes for stationary problems. As far as we are aware, zero-variance Monte-Carlo schemes for neutron-precursor kinetics have never been proposed before. We verify our construction with numerical calculations for a benchmark transport problem.