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This study addressed the problem of measuring the total mass of molten salt in a nuclear system such as a nuclear fuel electrorefiner or a molten salt reactor. In theory, soluble tracers can be add...

The 316L stainless steels (SS) have become one of the most common structural materials in nuclear system applications due to their excellent physicochemical performance. Selective laser melting (SLM) preparation, mechanical properties, and irradiation resistance of 316L SS reinforced by second-phase particles have aroused extensive attention. Here, the mechanical properties of 316L SS with different LaB6 contents processed by SLM before irradiation and the irradiation-induced swelling after 50 keV He+ irradiation at room temperature were investigated. Results showed that the microstructure was refined with the LaB6 addition, and the size of 316L SS subgrains decreased with the increase of LaB6. LaB6 reinforced 316L SS (316L-LaB6) exhibited higher hardness and yield strength compared with 316L SS without LaB6 addition. After 50 keV He+ irradiation, the irradiation-induced swelling rate of 316L-LaB6 was lower than that of 316L SS without LaB6 addition, indicating that LaB6 improved the irradiation resistance of 316L SS. Consequently, our study indicated the potential of using 316L-LaB6 as irradiation-resistant material.

The Kilowatt Reactor Using Stirling TechnologY (KRUSTY) was a prototypic nuclear-powered test of a 5-kW(thermal) Kilopower space reactor. This paper presents results from the KRUSTY nuclear system ...

This work extends to third-order previously published work on developing the adjoint sensitivity and uncertainty analysis of the numerical model of a polyethylene-reflected plutonium (acronym: PERP) OECD/NEA reactor physics benchmark. The PERP benchmark comprises 21,976 imprecisely known (uncertain) model parameters. Previous works have used the adjoint sensitivity analysis methodology to compute exactly and efficiently all of the 21,976 first-order and (21,976)2 second-order sensitivities of the PERP benchmark’s leakage response to all of the benchmark’s uncertain parameters, showing that the largest and most consequential 1st- and 2nd-order response sensitivities are with respect to the total microscopic cross sections. These results have motivated extending the previous adjoint-based derivations to third-order, leading to the derivation, in this work, of the exact mathematical expressions of the (180)3 third-order sensitivities of the PERP leakage response with respect to these total microscopic cross sections. The formulas derived in this work are valid not only for the PERP benchmark but can also be used for computing the 3rd-order sensitivities of the leakage response of any nuclear system involving fissionable material and internal or external neutron sources. Subsequent works will use the adjoint-based mathematical expressions obtained in this work to compute exactly and efficiently the numerical values of these (180)3 third-order sensitivities (which turned out to be very large and consequential) and use them for a third-order uncertainty analysis of the PERP benchmark’s leakage response.

In best estimate plus uncertainty approach for thermal-hydraulic simulation in nuclear engineering, a crucial step for the qualification of the scenario simulation is the discretization, i.e., the nodalization of nuclear power plants and related integral test facilities (ITFs). Since intermediate break loss-of-coolant accident (IBLOCA) simulation is getting more and more attention in this decade, we focused on the nodalization of an IBLOCA scenario—a primary loop (PKL) I2.2 benchmark delivered by the organization for economic cooperation and development PKL4-project—using the analyses of thermal-hydraulics for leaks and transients (ATHLET) code. This work followed mainly the nodalization methodology of Petruzzi and D'Auria, including both qualitative and quantitative criteria, being divided into three phases for component volume, steady-state, and transient, respectively. The authors used also some specific approaches: (1) for component volume qualification, a volume fractional parameter was introduced, considering not only the relative error of each component but also the volume fraction in the whole system (an 0.2% acceptability level was chosen for this parameter); (2) the experimental data were not used directly as a reference within the nodalization procedure but the calculated results delivered by the most refined nodalization. Based on the estimator of average amplitude in the fast Fourier transform-based method (FFTBM), the convergence, rationality, and an optimized result of nodalization in the simulation of an actual IBLOCA transient benchmark have been judged. After three phases of nodalization qualification, it has been proved that the final nodalization has the necessary degree of convergence for a good reproduction of the benchmark geometry, allowing the proper simulation of involved phenomena. Finally, a middle-refined nodalization was found as being optimal, fulfilling the convergence criteria with a reasonable central processing unit time consumption. The nodalization scheme in this work was not seen as being the single factor influencing the simulated results, but just as a prerequisite to allow further reliable improvements on the models used by ATHLET (aspects not referred to in this particular study). Therefore, the simulated results presented here will match the experimental ones only as general trends; improvements may be further achieved by using new and more precise models (e.g., for critical mass flow, heat transfer, countercurrent flow, etc.) in the system thermal-hydraulic code.

In this paper, a new M3Y-type effective nucleon–nucleon interaction, derived based on the lowest order constrained variational approach (LOCV) and termed B3Y-Fetal, has been used in DDM3Y1, BDM3Y1, BDM3Y2, and BDM3Y3 density-dependent versions in a heavy ion (HI) optical potential based on four types of a real folded potential and a phenomenological Woods–Saxon imaginary potential to study the elastic scattering of the $$^{16}$$ O+ $$^{16}$$ O nuclear system within the framework of the optical model (OM) by computing the associated differential cross sections at various incident energies. The results of the folding analyses have shown the DDB3Y1-Fetal and BDB3Y1-Fetal, out of the four folded potentials, give a reasonably better description of the elastic data of the nuclear system. These best-fit folded potentials are followed, in performance, by the BDB3Y2-Fetal, with the BDB3Y3-Fetal potential coming last. This performance trend was also demonstrated by the optical potentials based on the M3Y-Reid interaction. Furthermore, the best-fit folded potentials, renormalized by a factor $$N_\text {R}$$ of approximately 0.9, have been shown to reproduce the energy dependence of the real optical potential for $$^{16}$$ O scattering found in previous optical model analyses creditably well. In excellent agreement with previous works, they have also been identified in this work to belong to the family of deep refractive potentials because they have been able to reproduce and consistently describe the evolution of Airy-like structures, at large scattering angles, observed in the $$^{16}$$ O scattering data at different energies. Finally, a comparison of the performances of B3Y-Fetal and M3Y-Reid effective interactions undertaken in this work has shown impressive agreement between them.

The use of digital components in critical systems creates vulnerabilities. Artificial Intelligence (AI) and Machine Learning (ML) can be used towards the monitoring of a system, because of their ability to handle big volumes of data. Specifically, the physical nature of a category of these systems – the cyber physical systems, (CPSs) – permits the embedding of the concept of inference and reinforcement learning. According to this, a system can perform decision making by selecting actions, which later provide certain rewards. This idea is implemented on a simple nuclear system, to determine whether the system has the ability to adjust to a specific power level by making decisions about other variables, such as control rod heights. Some preliminary results show that the system is able to adjust its state after some time has passed.

International audience; French GENIV sodium-cooled fast reactor (SFR) system could include Americium (Am) recycling in the radial fertile blankets located in the outer core regions. An issue related to this option is the lack of knowledge regarding the in-pile behaviour of the Am-bearing blanket (AmBB). The DIAMINO separate-effect experiment was irradiated in the OSIRIS Material Test Reactor (MTR) with the goal of studying AmBB gaseous release and swelling as a function of temperature, AmBB microstructure and gas production rate.A brief description of the experiment is first provided, in terms of objectives and planning. The innovative design developed for the DIAMINO experiment is described in details. The DIAMINO irradiation time history is then summarized and the first results of non-destructive post-irradiation examinations are given.The LICOS fuel design code of the PLEIADES platform was used for the thermo-mechanical modelling of the DIAMINO experiment. The Pleiades platform, co-developed by CEA and its industrial partners EDF and FRAMATOME, gathers several fuel performance codes, each generally dedicated to the fuel element of a particular nuclear system. For its part, the LICOS code allows performing studies on innovative fuel elements or on the design of irradiation devices for instance. The thermo-mechanical modelling of the DIAMINO experiment device using the LICOS code is detailed in the paper together with the validation of the computations on the basis of some experimental temperature measurements performed on an in-pile mock-up of the experiment. The use of the simulation tool for the monitoring of the AmBB sample temperature under irradiation and for the post-irradiation calculations is explained and illustrated through some examples.

M2LFR-1000 is a medium-power modular lead-cooled fast reactor, developed by University of Science and Technology of China (USTC), aiming at achieving a reactor design fulfilling the Gen IV nuclear system requirements and meanwhile emphasizing the optimum safety and economics. In order to evaluate the safety performance of M2LFR-1000 reactor core, three typical transients are selected from initiating events, which are unprotected transient overpower (UTOP), unprotected loss of offsite power (ULOHS+ULOF) and increase of feedwater flowrate with primary pumps trip (IFW+PLOF). These three transients presented and discussed in this paper are performed with the code Analysis of THermal-hydraulics of LEaks and Transients (ATHLET), which is developed by Gesellschaft für Anlagen-und Reaktorsicherheit gGmbH (GRS). The results indicate that the M2LFR is safe enough under these three transients due to the good inherent safety features of the reactor, without human intervention, the reactor will reach a new steady state under UTOP condition. Keywords: Transient analysis, LFR, Forced circulation, ATHLET

We develop a novel method to compute first and second order statistical moments of the neutron kinetic density inside a nuclear system by solving the energy-dependent neutron diffusion equation. Ra...

Within the framework of an optical model, the quasielastic channel experimental data for the $$^{11}$$ Be + $$^{197}$$ Au system measured at energies below and around the Coulomb barrier are analyzed. For the analysis of the $$^{11}$$ Be + $$^{197}$$ Au system, we include Coulomb dipole excitations and long-range nuclear potential to account for a long-range effects of this halo nuclear system. Using the parameters obtained from $$\chi ^{2}$$ analysis, we successfully reproduce the quasielastic experimental angular distributions for the $$^{11}$$ Be + $$^{197}$$ Au system.

We investigate the low energy 20O+12C reaction at Ec.m. = 9.29 MeV populating the 32Si* nuclear system within dynamical cluster-decay model (DCM) and bring about the role of temperature (T) dependent binding energies in the reaction dynamics. T-dependent binding energies are one of the crucial ingredients of DCM used to calculate the fragmentation potential and hence the fusion cross-section. The inculcation of T-dependent binding energies from microscopic relativistic mean field (RMF) theory in comparison to that from Davidson formula, leads to considerable change in the fragmentation profile, preformation probability of different fragments. Subsequently, it affects the contribution of individual channel in the fusion cross-section associated with light charged particles (LCP) emission. It is noted that the statistical evapOR model under predicts the LCP cross-section σLCP. On the other hand, DCM calculated σLCP is in nice agreement with experimental data for both cases of T-dependent binding energies although contribution of 3H and 4He channels in σLCP changes significantly for both cases.

Level density $\rho(E,N,Z)$ is derived for a nuclear system with a given energy $E$, neutron $N$, and proton $Z$ particle numbers, within the semiclassical extended Thomas-Fermi and periodic-orbit theory beyond the Fermi-gas saddle-point method. We obtain $~~\rho \propto I_\nu(S)/S^\nu$,~~ where $I_\nu(S)$ is the modified Bessel function of the entropy $S$, and $\nu$ is related to the number of integrals of motion, except for the energy $E$. For small shell structure contribution one obtains within the micro-macroscopic approximation (MMA) the value of $\nu=2$ for $\rho(E,N,Z)$. In the opposite case of much larger shell structure contributions one finds a larger value of $\nu=3$. The MMA level density $\rho$ reaches the well-known Fermi gas asymptote for large excitation energies, and the finite micro-canonical limit for low excitation energies. Fitting the MMA $\rho(E,N,Z)$ to experimental data on a long isotope chain for low excitation energies, due mainly to the shell effects, one obtains results for the inverse level density parameter $K$, which differs significantly from that of neutron resonances., Comment: 26 pages, 3 figures, 1 table. arXiv admin note: text overlap with arXiv:2103.16480

The particle-number-conserving (PNC) method in the framework of cranked shell model (CSM) is developed to deal with the reflection-asymmetric nuclear system by applying the ${S}_{x}$ symmetry. Based on an octupole-deformed Nilsson potential, the alternating-parity bands in $^{236,238}\mathrm{U}$ and $^{238,240}\mathrm{Pu}$ are investigated. The experimental kinematic moments of inertia (MoI) and the angular momentum alignments of all studied bands are reproduced well in the PNC-CSM calculations. The striking difference of rotational behaviors between U and Pu isotopes can be linked to the strength of octupole correlations. The upbendings of the alternating-parity bands in $^{236,238}\mathrm{U}$ are due to the alignments of pairs of nucleons occupying $\ensuremath{\nu}{g}_{9/2}, \ensuremath{\pi}{f}_{7/2}$ orbitals and $\ensuremath{\nu}{j}_{15/2}, \ensuremath{\pi}{i}_{13/2}$ high-$j$ intruder orbitals. In particular, the interference terms of nucleon occupying the octupole-correlation pairs of ${\ensuremath{\nu}}^{2}{j}_{15/2}{g}_{9/2}$ and of ${\ensuremath{\pi}}^{2}{i}_{13/2}{f}_{7/2}$ give a very important contribution to the suddenly gained alignments.

We study two different methods to prepare excited states on a quantum computer, a key initial step to study dynamics within linear response theory. The first method uses unitary evolution for a short time $T=\mathcal{O}(\sqrt{1-F})$ to approximate the action of an excitation operator $\hat{O}$ with fidelity $F$ and success probability $P\approx1-F$. The second method probabilistically applies the excitation operator using the Linear Combination of Unitaries (LCU) algorithm. We benchmark these techniques on emulated and real quantum devices, using a toy model for thermal neutron-proton capture. Despite its larger memory footprint, the LCU-based method is efficient even on current generation noisy devices and can be implemented at a lower gate cost than a naive analysis would suggest. These findings show that quantum techniques designed to achieve good asymptotic scaling on fault tolerant quantum devices might also provide practical benefits on devices with limited connectivity and gate fidelity., 25 pages, 19 figures (some circuits shown as figures); small modifications; title changed; version accepted for publication

The recent progress of multiple chiral doublet bands (M$\chi$D) is reviewed for both experimental and theoretical sides. In particular, the experimental findings, theoretical predictions, selection rule for electromagnetic transitions, M$\chi$D with octupole correlations and some related topics are highlighted. Based on these discussions, it is of highly scientific interest to search for the more M$\chi$D as well as the possible chiral wobblers, chirality-parity quartet and chirality-pseudospin triplet (or quartet) bands in nuclear system., Comment: 9 pages, 2 figures

It is of practical significance to analyze the multi-physics process of nuclear system, which includes neutronics, heat transfer and thermoelasticity. Fission reaction is the heat source in system, the heat source will affect the distribution of temperature field, which will lead to the change of strain. Strain in turn will affect the distribution of neutron field. Therefore, it is necessary to analyze the distribution of neutron flux, temperature and strain in system. Three aspects of work have been carried out: 1) Based on Galerkin finite element theory, the governing equations of neutronics, heat transfer and thermoelasticity are established; 2) The multi-physics analysis code is developed; 3) The calculation results are analyzed and discussed.

The soliton existence in sub-atomic many-nucleon systems is discussed. In many nucleon dynamics represented by the nuclear time-dependent density functional formalism, much attention is paid to energy and mass dependence of the soliton existence. In conclusion, the existence of nuclear soliton is clarified if the temperature of nuclear system is from 10 to 30 MeV. With respect to the mass dependence $^{4}$He and $^{16}$O are suggested to be the candidates for the self-bound states exhibiting the property of nuclear soliton., Comment: [Invited] submitted to "Frontiers in Physics"

We discuss angular distributions of elastic, inelastic, and break-up cross-sections for the $$^{11}\hbox {Be} + ^{197}\hbox {Au}$$ system, measured at energies below and around the Coulomb barrier. To this end, we employ Coulomb dipole excitations and a long-range nuclear (LRN) potential in order to account for long-range effects of the halo nuclear system and break-up effects of the weakly bound structure. We then analyze recent experimental data, comprising three channels, viz., elastic, inelastic, and break-up cross-sections, at $$E_{\text {c.m.}}=29.6\hbox { MeV}$$ and $$E_{\text {c.m.}}=37.1\hbox { MeV}$$. From the parameter sets extracted using a $$\chi ^{2}$$ analysis, we successfully reproduce the experimental angular distributions of the elastic, inelastic, and break-up cross-sections for the $$^{11}\hbox {Be+}^{197}\hbox {Au}$$ system simultaneously. Finally, we discuss the necessity of the LRN potential around the Coulomb barrier from a detailed analysis of the experimental data.

A multiscale coupling algorithm has been developed and validated through the numerical simulation of the thermal hydraulic behavior of an unprotected loss of flow in the experimental TALL-3D facility. During the loss of flow the system goes from forced to natural circulation flow. TALL-3D is a liquid Lead Bismuth Eutectic (LBE) loop, with an oil-cooled secondary loop, developed according to the requirements for the experimental data for validation of coupled CFD and system codes. In this work we perform the coupling between the multigrid finite element code FEMuS and a system code, by using a defective coupling algorithm of a one-dimensional circuit and a three-dimensional test section with overlapping meshes. A multiscale and multiphysics coupling algorithm has been developed based on open-source SALOME platform. MED data structure and HDF5 functions have been used for all the field operations. The coupled system is solved for different computational cases: laminar natural circulation, turbulent k − ω with SUPG regularization and with standard up-wind regularization for the advection term. Each case is also simulated through two different heat exchange models: with constant and non constant turbulent Prandtl number. These tests show the importance of the coupling approach for the analysis of transient simulations where the three-dimensional phenomena play an important role.

In the current research, a safety allocation technique named the Critical Risks Method (CRM) has been developed. Starting from a literature review, we analyzed the shortcomings of conventional methods. The outcomes show the primary two criticalities of the most important safety allocation approaches: (1) They are developed for series configuration, but not for parallel ones; (2) they ordinarily give only qualitative outputs, but not quantitative ones. Moreover, by applying the conventional methods, an increase in safety of the units to ensure the safety target leads to an increase of the production costs of the units. The proposed strategy can overcome the shortcomings of traditional techniques with a safety approach useful to series–parallel systems in order to obtain quantitative outputs in terms of failures in a year. The CRM considers six factors that are able to ensure its applicability to a great variety of critical infrastructures. In addition, CRM is described by a simply analytic definition. The CRM was applied to a critical infrastructure (Liquid Nitrogen Cooling Installation) in a nuclear plant designed with series–parallel units. By comparing the CRM outputs with databank safety values, the proposed method was validated.

New methodologies for rationally safeguarding a nuclear system in terms of economics have been developed based on the Bayesian decision theory and the risk management approach. Two methodologies are formulated and presented. In the first method, the two terms in which the cost for an error (Type-I or Type-II error) event is multiplied by the probability of that event occurring and are linearly combined. Second method is formed by utilizing the ratio of two types of risks for each type of error event. The two methods proposed generate adjusted and optimized S (detection threshold) values under given conditions and depending on the expectation of costs for error events. The results show that the methods suggest adjusted S values in terms of the risk and the cost-benefit based on the error values. For instance, the Type-II error event is more forbidden for the system that treats more special nuclear materials (e.g. Pu) during a short period. Moreover, the long-time period without inspection could enhance opportunities for the Type-II error event occurring. These methods could contribute to a better understanding for managing the Type-I and Type-II error events in a nuclear system which should be safeguarded.

Cyber-physical systems are engineered systems that integrate physical processes and computational resources. But, by integrating cyber and physical worlds, the physical assets are vulnerable to cyber-attack. Two things are of importance for the security of cyber-physical assets: access to control inputs by the attacker, and the ability of an attacker to mask inputs. This combination of attacker control and masking measurements can allow an attacker to cause significant damage to a system while remaining undetected. By masking certain measurement signals, an attacker may affect the observability of the system and create a condition where part of the state space is unobservable, meaning that it is impossible to reconstruct those states. This is called an observability attack. This paper presents a technique for analyzing observability attacks. How an attacker can design an attack to maximize the impact on the unobservable states while minimizing the possibility of detection is discussed. Criteria for maintaining a stealthy attack are given, and a design method is provided. For a nuclear balance of plant system, combinations of sensor omissions are analyzed to find an observability attack with maximum impact and minimum detection. An appropriate attack input signal is created, an attack is simulated, and the system response is shown.

A new parameter set is generated for finite and infinite nuclear system within the effective field theory motivated relativistic mean field (ERMF) formalism. The isovector part of the ERMF model employed in the present study includes the coupling of nucleons to the {\delta} and \r{ho} mesons and the cross-coupling of \r{ho} mesons to the {\sigma} and {\omega} mesons. The results for the finite and infinite nuclear systems obtained using our parameter set are in harmony with the available experimental data. We find the maximum mass of the neutron star to be 2.03M\odot? and yet a relatively smaller radius at the canonical mass, 12.69 km, as required by the available data., Comment: 5 pages, 4 figures, Accepted Nucl. Phys. A

Nuclear power industry could be truly sustainable only under the condition of the Treaty on the Non- Proliferation of Nuclear Weapons. Thus, the issue of nuclear materials illicit diversion is crucial. One possible way to increase the resistance of the nuclear system to proliferation could be the increase of inherent security of nuclear materials used. One of the practical steps here could be the creation of intrinsic barriers in low-enriched uranium (LEU) fuel that is used in light water reactors worldwide. By the way, not only natural uranium could be used as raw material for such LEU, but also reprocessed uranium produced from spent nuclear fuel. In this study, proliferation resistance of enriched reprocessed uranium (in other words, commercial LEU made of reprocessed uranium) in the case of its covert diversion was analyzed. The conditions, under which this material could be turned into a direct use material in terms of IAEA was outlined. The scale of enrichment facility required to produce a significant quantity (SQ) of highly enriched uranium (HEU) throughout the duration of three months to two years, having the predetermined amount of diverted material (one SQ of LEU stolen from fresh fuel) was also assessed. Then, it was shown that such a feature of fuel made of reprocessed uranium as 232U presence makes the detection of potential diversion possible even for much smaller quantities of LEU than in the case of fuel made of natural uranium.

El artículo define aspectos metodológicos e instrumentales del modelo predictivo diseñado para el análisis del sistema castramental dispuesto por el concejo de Sevilla en la Baja Edad Media en torno a la Vía de la Plata. Para ello, se realizó una aproximación hermenéutica a los patrones de fortificación de este territorio histórico, identificando los factores determinantes en la implantación espacial que permitiesen inferir pautas locacionales. El objetivo fue la detección de torres, atalayas u otras estructuras defensivas satelitales que complementasen el sistema nuclear en torno al que se vertebraba este espacio castral evaluando el modo en que tales arquitecturas interaccionaban con las fortalezas conocidas. Para su caracterización se abordaron diversos análisis geoespaciales de intervisibilidad y transitabilidad espacial. Significando el hallazgo arqueológico de la Torre del Alto del Viso, resultante de la prospección de una de las áreas de alta potencialidad, se aporta el estudio comparando de los resultados analíticos soportados en cartografía predictiva derivada de la implementación a través de SIG de las distintas modelizaciones: booleana, resultante de una combinación binaria por álgebra de mapas; EMC, fundada en la superposición ponderada de variables normalizadas; Superposición Difusa, resultante de la aplicación de la lógica difusa al proceso analítico. The article defines methodological and instrumental aspects of the predicted model designed for the analysis of the castramental system arranged by the council of Seville in the Late Middle Ages around the Vía de la Plata. A hermeneutical approach to the fortification patterns of the historical territory was carried out, identifying factors of spatial implantation that allowed to infer locational patterns. The main aim was to identify towers, watchtowers and others defensive structures that could complete the nuclear system that originated this castral space by evaluating how these constructions were related to those known fortresses. In order to feature them, diverse inter-visibility and walkability geospatial analyses were undertaken. Evaluating the archaeological finding of the tower of Alto del Viso, resulting from the prospecting of one of the high potential areas, the comparative study of the analytical results supported in predictive cartography derived from GIS implementation of the different models is provided: Boolean, resulting from binary combination by map algebra; MCE, founded on the weighted superposition of normalized variables; fuzzy overlay, resulting from the application of fuzzy logic to the analytical process.

The elastic scattering angular distributions for 16O + 12C nuclear system have been analyzed using double folding potential of different interaction models: CDM3Y1, CDM3Y6, DDM3Y1 and BDM3Y1. We have extracted the renormalization factor N r for the different concerned interaction models. Potential created by BDM3Y1 model of interaction has the shallowest depth which reflects the necessity to use higher renormalization factor. The experimental angular distributions for 16O + 12C nuclear system in the energy range 115.9–230 MeV exhibited unmistakable refractive features and rainbow phenomenon.