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Three-dimensional fracture of UO2 ceramic pellets by phase field modeling

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Science China(physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 169-180页

作者： Wei Xiong Xuan Ye Hongzhang Cheng Xiaoming Liu institute of nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy Technology Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education Tsinghua University State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences School of engineering Science University of Chinese Academy of Sciences

Fracture is the primary failure type for the UO2ceramic pellets,which are operated under irradiation and thermal processes,and physically confined by the *** this work,by combining closely coupled physical processes of heat conduction,heat transfer,and mechanical deformation with the cohesive phase field framework,we proposed a high-precision modeling of quasistatic cracking of three-dimensional （3D） UO2ceramic fuel pellets under high temperature and *** simulation results agree well with the experimental results,indicating that the proposed method has the potential to capture 3D crack modes in the interested time ***,we studied the relation of the 3D fracture patterns of fuel pellets with the peak power *** was found that the power level plays a critical role in determining the competition between radial and circumferential cracks,as well as transverse penetrating cracks.

关键词： phase field method nuclear fuel pellet coupled thermo-mechanical model thermal fracture

Targets capture by distributed active swarms via bio-inspired reinforcement learning

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Science China(physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 210-221页

作者： Kun Xu Yue Li Jun Sun Shuyuan Du Xinpeng Di Yuguang Yang Bo Li institute of Biomechanics and Medical engineering Applied Mechanics Laboratory Department of Engineering MechanicsTsinghua University institute of nuclear and New Energy Technology Tsinghua University Shanghai Aerospace Control Technology institute Shanghai Key Laboratory of Aerospace Intelligent Control Technology College of Automation engineering Nanjing University of Aeronautics and Astronautics

Natural swarms arranged from cells to herds are usually decentralized but display intriguing collective intelligence in coordinating individuals across large scales to efficiently achieve their common goals. Learning from nature may provide new strategies for controlling collective dynamics of synthetic swarms to accomplish specific functions. Here, we present a bioinspired computational framework that steers distributed active swarms to collectively capture and merge targets via reinforcement learning. We exploit collective milling structures of natural herds to cage the targets, and adopt a switching control policy inspired by sperms' chiral dynamics to optimize the trajectories of individuals, through which the active swarms can selforganize to enclose single or multiple distant targets in a dynamical, adaptive and scalable manner. There exists a critical swarm size, beyond which the excessive competition between agents would generate large mechanical forces, leading to capture instability but enabling the transition from short-distance to long-distance merging capture of multiple targets. This work provides physical insights into distributed active swarms and could offer a multilevel, decentralized strategy toward controlling swarm robotics in wide applications such as bio-medical devices, machine immunity, and target clearance.

关键词： swarm intelligence robotics multi-tasks artificial intelligence bionics

Magnetic glass-ceramics

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Journal of Advanced Ceramics 2012年第2期1卷 138-143页

作者： Viorel SANDU Mirela Sidonia NICOLESCU Victor KUNCSER Raluca DAMIAN Elena SANDU national institute of Materials physics Magurele 077125Romania “horia hulubei”national institute of nuclear physics and engineering Magurele 077125Romania

We present the magnetic properties of magnetic glass ceramics obtained by crystallization of Fe containing borosilicate *** types of nucleators have been used:Cr2O3 and *** role of the nucleators proved to be crucial in the size and morphology of the crystallites developed within glassy matrix as well in the magnetic *** former stimulates the growth of regular single crystals uniformly dispersed within the matrix whereas the latter leads to the formation of grains made of tiny(30 nm),*** magnetic response depends on the amount of Fe ions left dispersed within glassy matrix as paramagnetic *** P2O5 leads to the best structural magnetite,almost 42%of Fe ions are left dispersed in the matrix without magnetic *** the case of Cr2O3,the paramagnetic Fe is decreased to 12%but structural deficiency in the occupancy of the Fe sites of magnetite is revealed by Mössbauer spectroscopy.

关键词： glass ceramics Fe3O4 Mössbauer spectroscopy grain growth

Computation of products of phase space factors and nuclear matrix elements for double beta decay

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Chinese physics C 2019年第6期43卷 74-79页

作者： S.Stoica International Centre for Advanced Training and Research in physics Subsidiary of INCDFM horia hulubei national institute of physics and nuclear engineering

nuclear matrix elements(NME) and phase space factors(PSF) entering the half-life formulas of the double-beta decay(DBD) process are two key quantities whose accurate computation still represents a challenge. In this study, we propose a new approach of calculating these, namely the direct computation of their product as an unique formula. This procedure allows a more coherent treatment of the nuclear approximations and input parameters appearing in both quantities and avoids possible confusion in the interpretation of DBD data due to different individual expressions adopted for PSF and NME(and consequently their reporting in different units) by different authors. Our calculations are performed for both two neutrino(2 vββ) and neutrinoless(0 vββ) decay modes, for five nuclei of the most experimental interest. Further, using the most recent experimental limits for 0νββ decay half-lives,we provide new constraints on the light mass neutrino parameter. Finally, by separating the factor representing the axial-vector constant to the forth power in the half-life formulas, we advance suggestions on how to reduce the errors introduced in the calculation by the uncertain value of this constant, exploiting the DBD data obtained from different isotopes and/or decay modes.

关键词： double-beta decay nuclear matrix elements phase space factors

Production of medical radioisotope ^(64)Cu by photoneutron reaction using ELI-NP γ-ray beam

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nuclear Science and Techniques 2016年第4期27卷 147-151页

作者： Wen Luo School of nuclear Science and Technology University of South China Extreme Light Infrastructure - nuclear physics (ELI-NP)/‘‘horia hulubei’’ National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH)

Copper-64 is a radioisotope of medical interest that could be used for positron emission tomography imaging and targeted radiotherapy of cancer. In this work,we investigated the possibility of producing the^(64)Cu isotope through a^(65)Cu(γ,n) reaction using high-intensity γ-beams produced at the Extreme Light Infrastructurenuclear physics facility(ELI-NP). The specific activity for^(64)Cu was obtained as a function of target geometry, irradiation time, and electron beam energy, which translates into γ-beam energy. Optimized conditions for the generation of^(64)Cu isotopes at the ELI-NP were discussed. We estimated that an achievable saturation specific activity is of the order of 1–2 m Ci/g for thin targets(radius 1–2 mm,thickness 1 cm) and for a γ-beam flux of 10^(11) s ~1. Based on these results, the ELI-NP could provide great potential for the production of some innovative radioisotopes of medical interest in sufficient quantities suitable for nuclear medicine research.

关键词：放射性同位素设施生产中子反应射线束正电子发射断层成像医用靶向治疗基础设施

Alpha decay of heavy and super heavy nuclei with a generalized electrostatic potential

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Chinese physics C 2020年第12期44卷 114-122页

作者： R.Budaca A.I.Budaca “horia hulubei”national institute for physics and nuclear engineering Str.Reactorului 30RO-077125POB-MG6 Bucharest-MǎgureleRomania

Half-lives ofαdecay for Z≥84 nuclei are calculated based on the WKB theory applied for a phenomenological potential barrier composed of a centrifugal contribution and a screened electrostatic interaction represented by a Hulthen *** favored decays,the model has a single adjustable parameter associated with the screening of the electrostatic *** description of half lives for unfavored decays requires an additional hindrance term.A good agreement with experimental data is obtained in all considered *** evolution of the screening parameter for each nucleus revealed its dependence on shell *** model is also used for theoretical predictions on a few nuclei with uncertain or incomplete decay information.

关键词： half-lives alpha decay superheavy elements

Strongly enhanced quadrupole deformation in a class of N≈Z nuclei driven by large-scale clustering?

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Chinese physics C 2021年第6期45卷 121-127页

作者： P.Petkov C.Muller-Gatermann "horia hulubei"national institute for physics and nuclear engineering R-76900 Bucharest-Magurele Romania Argonne national Laboratory 9700 S.Cass Avenue LemontIl 60439USA

The formation of large size clusters,and/or their relative motion as a possible excitation mode,are suggested to be closely related to the origin of deformation in specific cases,namely the case of two doubly-magic clusters or two clusters with nearby *** lifetime data in N=Z^(76)Sr and^(80)Zr leading to large B(E2)values are reproduced consistently and well within this approach,along with data for a few neighboring N≈*** results are compared to previous studies of^(32)S and^(20)Ne and all of them support the ideas of the large-scale cluster approach.

关键词： quadrupole collectivity clustering in nuclei nuclear structure absolute transition probabilities

Fusion reactions around the barrier for Be+^(238)U

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Chinese physics C 2021年第5期45卷 100-104页

作者： Bo Mei Dimiter L.Balabanski Wei Hua Yu-Hu Zhang Xiao-Hong Zhou Cen-Xi Yuan Jun Su Sino-French institute of nuclear engineering and Technology Sun Y at-sen UniversityZhuhai 519082China institute of Modern physics Chinese Academy of SciencesLanzhou 730000China Extreme Light Infrastructure nuclear physics “Horia Hulubei”National R&D Institute for Physics and Nuclear EngineeringStrada Reactorului 30077125 Bucharest MagureleRomania

Fusion-evaporation cross sections of^(238)U(^(9)Be,5n)^(242)Cm are measured over a wide energy range around the Coulomb *** measured cross sections are compared with model calculations using two codes,namely HIVAP2 and KE ***2 calculations overestimate the measured fusion-evaporation cross sections by a factor of approximately *** KEWPIE2 calculations,two approaches,namely the Wentzel-Kramers-Brillouin(WKB)approximation and the empirical barrier-distribution(EBD)method,are used for the capture probability;both of them properly describe the measured cross ***,fusion cross sections of^(7.9)Be+^(238)Umeas-ured in two experiments are applied to constrain model calculations further through three codes,i.e,HIVAP2,KEWPIE2,and *** in these codes are also examined by comparison with measured fusion cross *** the comparisons indicate that the K EWPIE2 calculations using the WKB approximation agree well with the measured cross sections of both fusion reactions 7.9 Be+^(238)U and the fusion-evaporation reaction 238U(9 Be,5n)242 *** using the fusion code CCFULL are also in good agreement with the measured fusion cross sections of 7.9 Be+^(238)U.

关键词： fusion-evaporation reaction ^(238)U fusion cross sections near barrier energies

High-energy hybrid femtosecond laser system demonstrating 2 × 10 PW capability

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High Power Laser Science and engineering 2020年第4期8卷 108-122页

作者： Fran?ois Lureau Guillaume Matras Olivier Chalus Christophe Derycke Thomas Morbieu Christophe Radier Olivier Casagrande Sébastien Laux Sandrine Ricaud Gilles Rey Alain Pellegrina Caroline Richard Laurent Boudjemaa Christophe Simon-Boisson Andrei Baleanu Romeo Banici Andrei Gradinariu Constantin Caldararu Bertrand De Boisdeffre Petru Ghenuche Andrei Naziru Georgios Kolliopoulos Liviu Neagu Razvan Dabu Ioan Dancus Daniel Ursescu Thales LAS France Thales Systems Romania Extreme Light Infrastructure – nuclear physics ‘Horia Hulubei' National Institute for Physics and Nuclear Engineering University of Bucharest Faculty of Physics

We report on a two-arm hybrid high-power laser system(HPLS) able to deliver 2 × 10 PW femtosecond pulses,developed at the Bucharest-Magurele Extreme Light Infrastructure nuclear physics(ELI-NP) Facility. A hybrid frontend(FE) based on a Ti:sapphire chirped pulse amplifier and a picosecond optical parametric chirped pulse amplifier based on beta barium borate(BBO) crystals, with a cross-polarized wave(XPW) filter in between, has been *** delivers 10 mJ laser pulses, at 10 Hz repetition rate, with more than 70 nm spectral bandwidth and high-intensity contrast, in the range of 1013:1. The high-energy Ti:sapphire amplifier stages of both arms were seeded from this common FE. The final high-energy amplifier, equipped with a 200 mm diameter Ti:sapphire crystal, has been pumped by six 100 J nanosecond frequency doubled Nd:glass lasers, at 1 pulse/min repetition rate. More than 300 J output pulse energy has been obtained by pumping with only 80% of the whole 600 J available pump energy. The compressor has a transmission efficiency of 74% and an output pulse duration of 22.7 fs was measured, thus demonstrating that the dual-arm HPLS has the capacity to generate 10 PW peak power femtosecond pulses. The reported results represent the cornerstone of the ELI-NP 2 × 10 PW femtosecond laser facility, devoted to fundamental and applied nuclear physics research.

关键词： lasers high-power laser pulses ultra-short laser pulses