bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multi-Physics Coupling Model for Thermal Hydraulics and Solute Transport in CRUD Deposits
Authors: Liu Yan , Liu Xiaojing , Du Sijia , Wang Jiageng , He Hui 
Published: April 2023

AbstractThe porous Chalk River Unidentified Deposit (CRUD) depositions on the fuel cladding have a great impact on the heat transfer and power distribution of the reactor, resulting in a decrease in reactor safety and economy. In current paper, a multi-physics model is developed to simulate thermal hydraulics and boron hideout within the CRUD depositions. Processes including heat transfer, pressure drop, capillary flow, solute transport, chemical reactions and radiolysis reactions are fully coupled. The coolant flows through the capillary tubes in the porous medium and evaporates into steam at the surface of chimneys. The solute diffuses into the porous medium by capillary flow and maintains its chemical equilibrium. Chemistry and thermal hydraulics are coupled by saturation temperature that varies with solute concentrations. The new model can reasonably predict the distributions of temperature, pressure, Darcy velocity and chemical concentrations. This model shows the effect of evaporation at the chimney surface on CRUD temperature and boric acid concentration. In addition, the results show that boron hideout is caused by the accumulation of boric acid and the precipitation of Li2B4O7 at the bottom of CRUD. The influence of morphology parameters such as porosity, thickness, and chimney geometry on heat transfer and solute transport within CRUD depositions is also evaluated.
Study on Composition Design of Enamel Coating and Its Resistance to Active Metal Vapor Corrosion
Authors: Jiang Y. F. , Li H. Y. , Chen J. , Shi X. Q. , Zhu Y. X. 
Published: April 2023

AbstractAfter evaporation of cerium metal (simulated radioactive substance) in a stainless steel plate in a production process, Ce and Fe elements are interdiffused at the bonding interface and Ce-Fe solid solution is formed. There are problems such as incomplete recovery of attached materials and increased surface roughness at the interface, which cannot be reused. In order to reduce radioactive iste generation, metallic enamel coating is prepared on stainless steel substrate with SiO2, Al2O3, Na2O, K2O, CaF2 and CoO and its resistance to active metal vapor corrosion at high temperature is studied. The results show that the enamel coating is closely bonded to the substrate, forming a chemical bond of Fe-Co rich phase. The enamel coating can stably form a film with cerium metal atoms, and the evaporation coating does not fall off. The microstructure results show that cerium oxide is formed at the bonding interface between the enamel coating and cerium metal, forming a stable chemical bond. Compared with stainless steel substrate, there is no interfacial corrosion caused by mutual diffusion between enamel coating and cerium metal at the bonding interface, so it can only desorb cerium metal without damaging the coating and realize multiple reuse.
Study on the Effects from Spacer Wires on Coolant Flow Within a Fuel Assembly Used in the CiADS Core
Authors: Li Yunxiang , Meng Lu , Li Song , Liu Bo , Wang Disi , Zhang Youpeng , Zhang Lu , Jiang Wei 
Published: April 2023

AbstractSpacer wires are frequently applied as the positioning components of fuel bundles in lead-based fast reactor fuel assemblies. It is extremely important to carry out the research of the impacts from spacer wires on coolant flow within fuel assemblies, and therefore the safety performances of reactor core. In this paper, the open source CFD calculation software OpenFOAM was adopted to perform the refined numerical simulation on the multi-pitch assembly model of 61 bundles and analyze the distribution of flow characteristics such as pressure, velocity, and temperature. The results show that: there is a pressure difference on both sides of the wires, which may cause the coolant to mix laterally; the mixing effect incurred by the wires may cause the uneven distribution of coolant velocity. There are obvious high-speed and low-speed zones, and the high-speed zone is located at the same position as the low-pressure zone. Due to the high flow rate in the peripheral sub-channel, the coolant temperature is lower. The maximum temperature difference at the outlet of the fuel assembly can reach 20K, which may cause local overheating and therefore cladding rupture under accidental conditions. The simulation can provide a reference for the correction of the calculation results of the 1D single-channel program and lay the foundation for the development of the subsequent two-phase flow model for fuel assemblies containing wire spacers.
Evaluation of Uncertainty for Determination of Trace Uranium in Biology by Laser Fluorescence Method
Authors: Wang Yajie , Wang Lufeng , Dong Chuanjiang , Li Li , Tang Mengqi , Sun Weizhong , Wu Yao 
Published: April 2023

AbstractLarge amounts of uranium-containing radioactive waste are generated in reactor operation and in the research and manufacture of nuclear fuel elements. At present, there are various uranium enrichment and separation methods such as reduction precipitation method, ion exchange method, solvent extraction method, membrane filtration method, adsorption method, and microorganism method to treat the uranium-containing radioactive waste generated in the related processes of nuclear facilities. However, the airborne effluent or liquid effluent discharged after treatment may still contain radioactive uranium. It is well known that uranium is a radioactive heavy metal element, and its radioactive and chemical toxicity cannot be ignored. Uranium in the environment enters the human body through the food route, and its long half-life can make the human body suffer from continuous radioactive internal radiation damage. As an environmental medium, organisms are closely related to the entry of uranium into the human body through food. Therefore, it is of great significance to carry out accurate measurement of uranium content in environmental-grade biological samples around nuclear facilities, however, complete and accurate measurement results include measurement data and uncertainty. Laser fluorescence method is a method for rapid analysis of uranium content in environmental samples. It has the advantages of high sensitivity, simple sample pretreatment, and wide measurement range, which has been widely used in nuclear industry, environmental monitoring and scientific research. At present, there is a lack of relevant reports on the uncertainty of the measurement of total uranium content in environmental-grade biological samples by laser fluorescence method. It is of great significance to accurately measure the uranium content in biological samples by evaluating the uncertainty of this method. In this paper, the WGJ-III trace uranium analyzer was used to analyze the uncertainty source of total uranium in environmental-grade biological samples by laser fluorescence method. The uncertainty measurement model was established, the uncertainty components were quantified, and the expanded uncertainty of the measurement of total uranium content in environmental biological samples was calculated. The evaluation results showed that the expanded uncertainty of a 0.05 g environmental biological sample is 10.8% (k = 2) without dilution, and the dominant uncertainty component is derived from the measurement uncertainty of sample fluorescence counting.
Research on ΔI Control Strategy During Rapid Power Reduction
Authors: Meng Desheng , Duan Rong , Li Zhijun 
Published: April 2023

AbstractCold source for the cooling system is provided by CRF pump in nuclear power plant. During failure of CRF pump, a rapid core power reduction to a lower power level is needed, which poses a challenge to ΔI control of the core. Based on the requirements of operating technical specifications, the influence of various factors concerned the ΔI control strategy such as cycle burn-up, low power level and power reduction methods is researched for the rapid power reduction process in a certain balance cycle. Meanwhile, sensitivity analysis is carried out on the action of the control banks for different phases during the rapid power reduction process. Based on the analysis of the main influencing factors, proposal on the rapid power reduction strategy related to the reduced power level, power reduction method and different characteristic burn-up is put forward. The match of the cooling capacity of the CRF pump and the reduced core power is realized, thus ensure the safety and economy performance of reactor core.
Heterogeneous Reactivity Effect Analysis of Pu Spots Considering Grain Size Distribution Based on MOC
Authors: Ohara Masato , Ogawa Akifumi , Kitada Takanori , Takeda Satoshi 
Published: April 2023

AbstractIn the process of Mixed Oxide (MOX) fuel fabrication, plutonium grains, called plutonium spots (Pu spots), occur in MOX fuel because uranium and plutonium cannot be mixed completely. The previous study showed that the prediction accuracy of criticality is improved by considering the heterogeneity of Pu spots in MOX fuel in the analysis of some critical experiments. The analysis of the heterogeneity has been performed by Monte Carlo calculations, to ensure that core geometry and self-shielding effects are accurately considered in nuclear calculations. However, the results of Monte Carlo calculations are obtained with the statistical errors, thus the small reactivity worth is difficult to be analyzed. Therefore, in the previous study, the heterogeneous model by using a method devised by R. Sanchez was introduced into OpenMOC that is deterministic calculation code. Although there are numerous sizes of Pu spots in MOX fuel, an only single size of the grain could be considered in the modified OpenMOC. Therefore, in this study, the modified OpenMOC code was additionally modified to consider the grain size distribution of Pu spots.The calculation result obtained by the additionally modified OpenMOC shows that the heterogeneous reactivity effect caused by numerous grain sizes of Pu spots is evaluated at −0.190%Δk/kk’ at highly enriched fuels. On the other hand, a heterogeneous reactivity effect by single grain size is evaluated at −0.225%Δk/kk’. The additionally modified OpenMOC makes it possible to study the effect of considering the grain size distribution of Pu spots in MOX fuel.
Study of Stress Analysis Method for Floating Nuclear Power Plant Containment Under Combined Multiple Loads
Authors: Li Jiyue , Wang Donghui , Zhang Meng , Liu Hongbing , Qu Xianqiang 
Published: April 2023

AbstractFloating nuclear power plants (FNPP) are a combination of small nuclear reactors and hull structures. The applicable design codes and simulation analysis methods of floating nuclear power plants are nearly seldom, especially for the ultimate strength of containment considering multi loads. In order to analyze the structural strength of the steel containment of a floating nuclear power plant under the combined action of multiple loads, the structural response is analyzed in ANSYS considering the external hull loads and internal containment loads such as wave loads, wind loads, current loads, hull impact loads, internal pressure and temperature of the containment. The structural response result from wind, wave, current, internal pressure and temperature loads are calculated, separately, to obtain the stress field of the containment. Finally, the stress fields of the containment generated by each load are superimposed to obtain the stress distribution characteristics of the containment, and then strength assessment and stress analysis are performed.
Numerical Simulation of Flow Boiling Heat Transfer in Helical Tubes Under Marine Conditions
Authors: Yuan Leqi , Cheng Kun , Bian Haozhi , Liao Yaping , Jiang Chenxi 
Published: April 2023

AbstractLead-based cooled reactors in most countries and some small reactors at sea use helical tube steam generators. Compared with U-tubes, the convection heat transfer coefficient in the spiral tube is higher, the structure is more compact, and the secondary flow is generated under the action of centrifugal force and gravity, which can achieve the effect of wetting the inner wall of the tube. However, due to the importance of the steam generator in the reactor and the complexity of the flow and boiling in the helical tube, the aggregation behavior of bubbles, the distribution of the two-phase interface and the secondary flow in the tube will significantly affect the heat transfer characteristics, so the gas-liquid phase in the tube is studied. Distribution, changes in heat transfer coefficients, and fluid flow characteristics are very important.In order to study the boiling heat transfer characteristics of helical once-through steam generators under static and marine conditions to provide safe and reliable energy supply for offshore facilities such as marine floating, this study uses STAR-CCM+ software, VOF method and Rohsenow boiling model to study the heat transfer capacity and flow characteristics of flow boiling in a helical tube under swaying and tilting conditions. The gas-liquid phase distribution characteristics, secondary flow variation characteristics and convective heat transfer coefficient of the fluid under different swing functions and inclined positions are obtained by numerical calculation, and the law of physical parameters changing with the cycle is found. The research results show that the secondary flow and heat transfer capacity in the tube change with the cycle, and the change is most obvious at the tube length of 0.8m. 5% of the normal condition; when the inclination angle is 45°, the maximum increase of the convection heat transfer coefficient is 16.8%, and the maximum decrease is 6.6%.
Analytical Method Research of Source Term for Steam Generator Tube Rupture Accident of Small Modular Reactor
Authors: Xia Ming-ming , Wang Jun-long , Zhu Jian-ping , Tian Chao , Liu Jia-jia 
Published: April 2023

AbstractBased on the full reference to the existing engineering practice and safety review experience, and considering the actual design characteristics of the small modular reactor ACP100, a set of source term analysis method suitable for ACP100 of the steam generator tube rupture (SGTR) accident is proposed, and the source term analysis and consequence evaluation of ACP100 SGTR accident was carried out using this method. The analysis shows that the radiological consequences of the accident source term calculated by this method meet the acceptance criteria of small modular reactor. The analysis results of this article can provide support for the follow-up review of accident source term of ACP100.
Electroweak-flavour and quark-lepton unification: a family non-universal path
Authors: Davighi Joe , Isidori Gino , Pesut Marko 
Published: April 2023

Abstract
We present a family-non-universal extension of the Standard Model where the first two families feature both quark-lepton and electroweak-flavour unification, via the SU(4) Sp(4)L Sp(4)R gauge group, whereas quark-lepton unification for the third family is realised à la Pati-Salam. Via staggered symmetry breaking steps, this construction offers a natural explanation for the observed hierarchical pattern of fermion masses and mixings, while providing a natural suppression for flavour-changing processes involving the first two generations. The last-but-one step in the symmetry-breaking chain is a non-universal 4321 model, characterised by a vector leptoquark naturally coupled mainly to the third generation. The stability of the Higgs sector points to a 4321 → SM symmetry-breaking scale around the TeV, with interesting phenomenological consequences in B physics and collider processes that differ from those of other known 4321 completions.
Discrete bulk reconstruction
Authors: Aaronson Scott , Pollack Jason 
Published: April 2023

Abstract
According to the AdS/CFT correspondence, the geometries of certain spacetimes are fully determined by quantum states that live on their boundaries — indeed, by the von Neumann entropies of portions of those boundary states. This work investigates to what extent the geometries can be reconstructed from the entropies in polynomial time. Bouland, Fefferman, and Vazirani (2019) argued that the AdS/CFT map can be exponentially complex if one wants to reconstruct regions such as the interiors of black holes. Our main result provides a sort of converse: we show that, in the special case of a single 1D boundary divided into N “atomic regions”, if the input data consists of a list of entropies of contiguous boundary regions, and if the entropies satisfy a single inequality called Strong Subadditivity, then we can construct a graph model for the bulk in linear time. Moreover, the bulk graph is planar, it has O(N2) vertices (the information-theoretic minimum), and it’s “universal”, with only the edge weights depending on the specific entropies in question. From a combinatorial perspective, our problem boils down to an “inverse” of the famous min-cut problem: rather than being given a graph and asked to find a min-cut, here we’re given the values of min-cuts separating various sets of vertices, and need to find a weighted undirected graph consistent with those values. Our solution to this problem relies on the notion of a “bulkless” graph, which might be of independent interest for AdS/CFT. We also make initial progress on the case of multiple 1D boundaries — where the boundaries could be connected via wormholes — including an upper bound of O(N4) vertices whenever an embeddable bulk graph exists (thus putting the problem into the complexity class NP).
Integrable models based on non-semi-simple groups and plane wave target spacetimes
Authors: Sfetsos Konstantinos , Siampos Konstantinos 
Published: April 2023

Abstract
We initiate the construction of integrable λ-deformed WZW models based on non-semisimple groups. We focus on the four-dimensional case whose underlying symmetries are based on the non-semisimple group $$ {E}_2^c $$

E
2
c

. The corresponding gravitational backgrounds of Lorentzian signature are plane waves which can be obtained as Penrose limits of the λ-deformed SU(2) background times a timelike coordinate for appropriate choices of the λ-matrix. We construct two such deformations which we demonstrate to be integrable. They both deform the Nappi-Witten plane wave and are inequivalent. Nevertheless, they have the same underlying symmetry algebra which is a Saletan-type contraction of that for the λ-deformed SU(2) background with a timelike direction. We also construct a plane wave from the Penrose limit of the λ-deformation of the $$ \frac{\textrm{SU}(2)}{\textrm{U}(1)} $$

SU

2

U

1

coset CFT times a timelike coordinate which represents the deformation of a logarithmic CFT constructed in the past. Finally, we briefly consider contractions based on the simplest Yang-baxter σ-models.
Extensions of two-field mimetic gravity
Authors: Zheng Yunlong , Rao Haomin 
Published: April 2023

Abstract
Two-field mimetic gravity was recently realized by looking at the singular limit of the conformal transformation between the auxiliary metric and the physical metric with two scalar fields involved. In this paper, we reanalyze the singular conformal limit and find a more general solution for the conformal factor A, which greatly broadens the form of two-field mimetic constraint and thus extends the two-field mimetic gravity. We find the general setup still mimics the role of dark matter at the cosmological background level. Moreover, we extend the action by introducing extra possible term for phenomenological interests. Surprisingly, some special cases are found to be equivalent to general relativity, k-essence theory and Galileon theory. Finally, we further extend the theory by allowing the expression of mimetic constraint to be arbitrary without imposed condition, and show that the dark matter-like behavior is unaffected even in this extension.
Actively transcribed rDNA and distal junction (DJ) sequence are involved in association of NORs with nucleoli
Authors: Liskovykh Mikhail , Petrov Nikolai S. , Noskov Vladimir N. , Masumoto Hiroshi , Earnshaw William C. , Schlessinger David , Shabalina Svetlana A. , Larionov Vladimir , Kouprina Natalay 
Published: April 2023

AbstractAlthough they are organelles without a limiting membrane, nucleoli have an exclusive structure, built upon the rDNA-rich acrocentric short arms of five human chromosomes (nucleolar organizer regions or NORs). This has raised the question: what are the structural features of a chromosome required for its inclusion in a nucleolus? Previous work has suggested that sequences adjacent to the tandemly repeated rDNA repeat units (DJ, distal junction sequence) may be involved, and we have extended such studies by addressing several issues related to the requirements for the association of NORs with nucleoli. We exploited both a set of somatic cell hybrids containing individual human acrocentric chromosomes and a set of Human Artificial Chromosomes (HACs) carrying different parts of a NOR, including an rDNA unit or DJ or PJ (proximal junction) sequence. Association of NORs with nucleoli was increased when constituent rDNA was transcribed and may be also affected by the status of heterochromatin blocks formed next to the rDNA arrays. Furthermore, our data suggest that a relatively small size DJ region, highly conserved in evolution, is also involved, along with the rDNA repeats, in the localization of p-arms of acrocentric chromosomes in nucleoli. Thus, we infer a cooperative action of rDNA sequence—stimulated by its activity—and sequences distal to rDNA contributing to incorporation into nucleoli. Analysis of NOR sequences also identified LncRNA_038958 in the DJ, a candidate transcript with the region of the suggested promoter that is located close to the DJ/rDNA boundary and contains CTCF binding sites. This LncRNA may affect RNA Polymerase I and/or nucleolar activity. Our findings provide the basis for future studies to determine which RNAs and proteins interact critically with NOR sequences to organize the higher-order structure of nucleoli and their function in normal cells and pathological states.