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The International Thermonuclear Experimental Reactor (ITER) is one of the largest international cooperative projects with many participants from different research groups in institutes and universi...

To study the burnup features of accelerator-driven subcritical systems (ADSs), simplified transmutation trajectories are imperative to make the simulation process more effective with acceptable pre...

Cadmium (Cd) is a ubiquitous environmental pollutant, which mainly input to the aquatic environment through discharge of industrial and agricultural waste, can be a threat to human and animal health. Selenium (Se) possesses a beneficial role in protecting animals and ameliorating the toxic effects of Cd. However, the comparative antagonistic effects of different Se sources such as inorganic, organic Se and nano-form Se on Cd toxicity are still under-investigated. Hence, the purpose of this study was to evaluate the comparative of Se sources antagonism on Cd-induced nephrotoxicity via oxidative stress and selenoproteome transcription. In the present study, Cd-diet disturbed in the system balance of 5 trace elements (Zinc (Zn), copper (Cu), Iron (Fe), Se, Cd) and impaired renal function. Se sources, including nano- Se (NS), Se- yeast (SY), sodium selenite (SS) and mixed selenium (MS) significantly recovered the balance of 4 trace elements (Zn, Cu, Cd, Se) and renal impaired indexes (blood urea nitrogen (BUN) and creatinine (CREA)). Histological appearance of Cd-treated kidney indicated renal tubular epithelial vacuoles, particle degeneration and enlarged capsular space. Ultrastructure observation results illustrated that Cd-induced mitochondrial cristae reduction, membrane disappearance, and nuclear deformation. Treatment with Se sources, NS appeared a better impact on improving kidney tissues against the pathological alterations resulting from Cd administration. Meanwhile, NS reflected a significant impact on relieving Cd-induced kidney oxidative damage, and significantly restored the antioxidant defense system of the body. Our findings also showed NS ameliorated the Cd-induced downtrends expression of selenoproteome and selenoprotein synthesis related transcription factors. Overall, NS was the most effective Se source in avoiding of Cd cumulative toxicity, improving antioxidant capacity and regulating of selenoproteome transcriptome and selenoprotein synthesis related transcription factors expression, which contributes to ameliorate Cd-induced nephrotoxicity in chickens. These results demonstrated diet supplement with NS may prove to be an effective approach for alleviating Cd toxicity and minimizing Cd -induced health risk.

MCNPX is a general purpose Monte Carlo radiation transport code designed to track many particle types over broad ranges of energies and it has the potential to deal with Accelerator Driven System (ADS) problems. The neutronics design and analysis of ADS using MCNPX code is significantly complex mainly on constructing the three dimensional geometry model, especially when there is an additional spallation target coupled with the subcritical reactor constructed by abundant nested repeated structures in several levels. This modeling process has long been recognized as a time consuming, tedious and error-prone task, which is hard to master for novice users. Therefore, it is imperative to build a code system that can translate CAD models of ADS to the native language of MCNPX code. In this context of demand, a code system named CAD-PSMC (FreeCAD based parsing script for MCNPX code) has been developed to solve the ADS modeling conversion problems. In the framework of this code, hierarchical tree-based basic geometry classes and Boolean&Affine operations have been established with a mapping relationship to MCNPX code. Additionally, ray-casting technology and Markov chain based iteration method have been proposed to solve the problem of spline surfaces in complex geometries. Finally, the applicability and accuracy of CAD-PSMC code have been demonstrated by comparing with various reference models and numerical calculation results.

An electromagnetic shunt damper (EMSD) refers to the electromagnetic device connected to a specially designed shunt circuit that suppresses structural vibration. The analogy between mechanical and electrical systems offers the theoretical possibility of imitating various mechanical dampers using EMSDs. However, the inherent resistance of the whole circuit unfavorably affects the EMSD performance, including the analogous relationship. This study proposes a novel passive solution to address this practical limitation by using a negative impedance converter with voltage inversion (VNIC) to partially cancel the inherent resistance of shunt circuits. The benefit of the VNIC is revealed through theoretical and experimental studies. With the aid of a VNIC, a single electromagnetic device can mimic the versatile behaviors of different types of conventional dampers, such as viscous fluid, viscoelastic, inerter, and tuned inerter dampers, by conveniently adjusting the designs and parameters of shunt circuits. To the best of the authors’ knowledge, the versatility of EMSDs presented in this paper has not been experimentally illustrated in the literature.

Accelerator driven system (ADS) is an advanced nuclear system with high inherent safety feature, which can transmute the nuclear waste including minor actinides (MA) and long-lived fission products (LLFPs) into short-lived fission products. In order to accomplish the neutronic simulation in ADS, a conventional way can be divided into two steps, namely the physical process of proton beam bombarding spallation target (FLUKA) and the neutron transport process in subcritical reactor coupling with a spallation neutron source (OpenMC). However, there are some difficulties in the modeling process for ADS, such as the inconsistent modeling process between FLUKA and OpenMC codes, and the error-prone process of constructing complex geometries. Therefore, it is imperative to build a code system that can convert the CAD modeling files into the input cards of Monte Carlo codes. In this context, a code system named CAD-PSFO (FreeCAD based parsing script for FLUKA and OpenMC) has been developed to solve the modeling conversion problem in ADS, in which basic geometry and boolean logic classes have been established with a mapping relationship to FLUKA and OpenMC codes, and ray-casting technology based iteration method has been proposed to solve the problem of higher-order surfaces in complex geometries. Finally, CAD-PSFO has been verified and validated by comparing with a reference model, two benchmarks, and two simulation tests.

Electromagnetic dampers (EMDs), which are regarded as an emerging type of dampers, have recently drawn increasing research interests in structural vibration control due to their unique advantages over conventional damper types. Although advanced synthetic impedance and energy harvesting functions of EMDs have been separately investigated, their integration has not been explored to the best of the authors’ knowledge. The major obstacle herein is that the former versatile damper behavior is normally realized by consuming input energy, whereas the latter can only provide pure damping behavior comparable to passive viscous dampers while producing output energy. To fill this research gap, this study proposes a novel H-bridge circuit based EMD (HB-EMD), which allows bidirectional power flow between the EMD and the energy pool, and enables the realization of versatile damper behavior with the salient self-powered feature. The system design, working mechanism, synthetic impedance technique, power analyses, and emulation of various conventional dampers by using HB-EMD, are analytically, numerically, and experimentally examined. Scalability issues of HB-EMD are also discussed to shed light on future large-scale applications.

Electromagnetic shunt damper (EMSD) is an emerging damper type capable of mimicking conventional mechanical dampers using their electrical circuit counterparts. Damping, stiffness, and inertance within mechanical domain can be emulated by resistance, inductance, and capacitance from electrical domain, respectively. In particular, four representative conventional damper types, namely, viscous fluid damper (VFD), viscoelastic damper (VED), inerter damper (ID), and tuned inerter damper (TID), are emulated by an EMSD in this paper, thereby forming EMSD-VFD, EMSD-VED, EMSD-ID and EMSD-TID, respectively. Their control performances when installed in a vibration isolation system are subsequently studied both analytically and experimentally. The behavior of EMSD can be easily tuned by changing the external circuits connected to the electromagnetic damper. Moreover, these four types of EMSDs possess complementary isolation performances across the frequency spectrum, which implies that different optimal circuits should be selected in different frequency bands to achieve the best isolation performance. A broadband vibration isolation technique by automatically switching among sub-circuits integrated in a single circuit board will be a promising future research direction.

Accelerator driven subcritical system (ADS) is a kind of clean nuclear facility with inherent safety features. ADS facilities mainly put emphasis on studying the two following categories of isotopes, namely, the minor actinide (MA) and long-lived fission products (LLFP). However, some general burnup codes lack depletion chains for specific heavy isotopes with MA included, or treat a series of isotopes, including LLFP, as pseudo nuclides. Taking into account the above characteristics, a burnup-transport code system OMCB (OpenMC based Burnup code) has been developed based on transmutation trajectory analysis (TTA) method and Bateman equations, coupling with OpenMC code for ADS facilities. In order to make the depletion calculation process more effective and accurate, three kinds of iterations and one terminate criteria have been proposed for searching the depletion chains. Moreover, a scan mode method based high order differential expression has been proposed to remove the infinite terms in Bateman equations. Finally, a concept of sub-step predictor calculation has been introduced by combining both linear and quadratic interpolation methods, which makes cross section time-dependent in each depletion step. Four benchmarks have been used to validate OMCB code. The numerical tests demonstrate that OMCB code has a good agreement in comparison with the reference results and can be used in ADS facilities.

Purpose The purpose of this paper is to present a simple and effective method to search the optimal turn-on and turn-off angles on-line for the control of the switched reluctance motor (SRM). The optimal turn-on and turn-off angles are defined as the ones that can meet torque production requirements with minimum copper loss. Design/methodology/approach The optimal turn-on and turn-off angles are first defined based on the analysis of the SRM losses and torque production principles. Then the algorithm for optimal angles searching is developed, and the searching parameters are determined through analytical computation. The optimal angles are approached on-line with iterative process. Simulation and experiments are finally performed to verify the proposed method. Findings The presented method can meet torque production requirements while copper loss is minimized. The optimal turn-on and turn-off angles are generally approached within five phase cycles for most of the SRM operation modes. Furthermore, the SRM drive system using the presented method exhibits good dynamics during starting and sudden load operations. Practical implications The presented method is simple, and implementation of it is easy. It is an eligible candidate for industrial applications where energy conversion efficiency is crucial. Originality/value The optimal turn-off angle definition that considers both torque production and copper loss minimization is proposed. The turn-on and turn-off angles are searched independently on-line with little SRM geometrical information. The searching steps are derived through analytical computation and qualitative analysis so that both the searching speed and algorithm convergence are balanced.

Long bridge cables are vulnerable to unanticipated large vibrations induced by earthquakes, wind, and traffic loads. The use of various dampers, including inerter dampers (IDs), as an effec...

The DGT (Dense Granular spallation Target) is the crucial component in CiADS (China initiative Accelerator Driven subcritical System), which is the important device in connecting the high power accelerator and the subcritical reactor. In order to keep the stable and reliable running of the coupling system, the temperature control of the DGT should be carefully studied and optimized, where the gravity driven tungsten alloy granules are considered as the spallation target material and the corresponding coolant, and the working temperature in normal operation condition should be controlled around the pre-setting value without bringing the large perturbation. Two kinds of control approaches have been adopted in this research in adjusting the temperature inside the DGT, which are the intensity of proton beam and the flow speed of tungsten alloy granules. Therefore, the simulation method and the PID (Proportional Integral Derivative) controller have been established based on the cooperation of two approaches in order to better adapt to the temperature control of the DGT. Moreover, the genetic algorithm has been employed to select and optimize the key parameters in PID controller for the purpose of substituting the experiential selection in traditional manually iterative process. Finally, the temperature control system has been evaluated based on the reference control scenarios, and all the simulation results demonstrate that the optimized method has applicability and feasibility in the temperature control of the spallation target system.

In this paper, the benchmark experiment of the lead reactivity worth was introduced in detail, which has been carried out under a super-critical state at the light water reactor of the VENUS-II experimental facility. The reactivity worth of the cylindrical lead target was measured and processed as 142.0 ± 11.3 pcm by the period method. In simulations, the reactivity worth of the lead target was calculated by MCNP with the five libraries, i.e., ENDF/B-VII.1, ENDF/B-VII.0, JENDL-4.0, CENDL-3.1 and JEFF-3.2. By comparisons, the MCNP simulated results of the lead reactivity worth with ENDF/B-VII.1, ENDF/B-VII.0, CENDL-3.1 and JEFF-3.2 libraries are underestimated, and that of JENDL-4.0 shows slight better agreement with the experiment data within errors. Through the perturbation analysis, the (n, el) reaction channel is most related to the positive reactivity worth of the lead target. Additionally, the reaction rates of the (n, el), (n, inl) and (n, γ) channels were calculated by FM card in MCNP. It is observed that the (n, γ) reaction rates from different libraries show the maximum difference, which is due to the discrepancy of the (n, γ) cross sections in the thermal neutron region. In conclusion, the lead cross sections from the main libraries in the world have been preliminarily validated based on the measurements, which lays the foundation for the engineering design of CIADS.

China is developing an ADS (Accelerator-Driven System) research device named the China initiative accelerator-driven system (CiADS). When performing a safety analysis of this new proposed design, the core behavior during the steam generator tube rupture (SGTR) accident has to be investigated. The purpose of our research in this paper is to investigate the impact from different heating conditions and inlet steam contents on steam bubble and coolant temperature distributions in ADS fuel assemblies during a postulated SGTR accident by performing necessary computational fluid dynamics (CFD) simulations. In this research, the open source CFD calculation software OpenFOAM, together with the two-phase VOF (Volume of Fluid) model were used to simulate the steam bubble behavior in heavy liquid metal flow. The model was validated with experimental results published in the open literature. Based on our simulation results, it can be noticed that steam bubbles will accumulate at the periphery region of fuel assemblies, and the maximum temperature in fuel assembly will not overwhelm its working limit during the postulated SGTR accident when the steam content at assembly inlet is less than 15%.

In this paper, a benchmark experiment of tungsten granular target worth has been performed on the VENUS-II light water zero-power facility of CIAE in Beijing. The reactivity worth of the tungsten granular target was measured and processed as ( - 1.007 ± 0.096 ) mk by a period method. In MCNP simulations, three modeling methods of tungsten grains, i.e., the homogeneous, body center and face center models, were used to calculate the tungsten granular target reactivity worth. Through the comparison, the simulated tungsten granular target reactivity worth values with three modeling methods are in good agreement with the experimental result within errors and the maximum C/E and (C-E) deviations are respectively 3.7% and 0.037 mk. By the perturbation analysis in MCNP and the comparison on the cross sections of tungsten, iron and nickel, the negative reactivity worth of tungsten granular target is mainly caused by the tungsten radiation capture reaction channel. It is recommended to adopt the efficient homogeneous modeling method to simulate the tungsten granular target, which establishes a foundation for the systematic integration design of CIADS.

The temperature control of the spallation target in accelerator driven subcritical system is the important issue that has the direct impact on stable and reliable operation of the coupling system. The China initiative accelerator driven subcritical system (CiADS) is composed by three facilities, including the high power accelerator, dense granular spallation target (DGT) and the subcritical reactor, where the DGT is the key component in connecting the accelerator and subcritical reactor, and the gravity driven tungsten alloy granules are considered as the material and coolant for the spallation target. In order to keep the working temperature in normal operation condition around the presetting value without bringing the large perturbation, the intensity of proton beam and the flow speed of tungsten alloy granules are considered as the main control approaches in adjusting the temperature inside the DGT, and the proportional integral derivative (PID) controller has been established based on the two approaches for the better adaptability to the temperature control in spallation target system. Moreover, the simulation method and quantum evolutionary algorithm have been employed for the selection and optimization of main parameters in PID controller in order to substitute the time consuming and error prone tasks in traditional experiential selection process. Finally, the reference control scenarios have been used to demonstrate the feasibility and applicability of optimized method for the temperature control of the DGT system in CiADS.

The stellarator plasmas devices have some advantages in steady state operation with less magneto hydrodynamic activities, and the development of stellarator-type FFHR (Fusion-Fission Hybird Reactor) can provide viable energy in the foreseeable future with less requirements to the plasmas technology compared with the pure fusion system. However, the neutronics design of the stellarator-type FFHR has some challenges and difficulties, since the construction of helical structures with large number of high order spline surfaces are the extremely complicated process, and the physical parameters of the complex model have to be changed frequently in the primary design stage, which make the corresponding manual input simulation work into the time consuming and error prone tasks. In this context, the CAD optimization method has been used in converting the dense mesh oriented CAD structure to the low poly style, and the CAD-PSFO code has been employed for the modeling transformation process in Monte Carlo calculation. The thorium resource has been selected as the breeding material for the stellarator-type FFHR, and the polonium and natural abundance of uranium have been used as the seed fuel for the initial loading in order to get the high energy multiplication factor. The OMCB (OpenMC based Burnup code) has been introduced to study the burnup features, and stellarator-type FFHR has been designed as the multi-purposes facility that can keep tritium self-sufficiency and get the high breeding ratio with steady energy output.

The China initiative Accelerator Driven subcritical System (CiADS) has already embarked on a plan to be built in south China’s Guangdong province for the research purpose of lead–bismuth cooled fast reactor and minor-actinide transmutation technology. In comparison with the other critical reactors, it is difficult to arrange the fuel handling equipment and to make the whole core refueling plan, since there is a proton beam tube in the central of the core and the operating environment is completely opaque. In this context, an innovation design of the spallation target and fuel handling system is proposed in Institute of Modern Physics, Chinese Academy of Sciences (IMPCAS) based on an immersive Virtual Reality (VR) platform, which can fulfill the loading and refueling procedure without mutual collisions, and provide the real-time roaming experience as in the real world. Detailed information of the handling system have been introduced including the optimized logical structure in consideration of the movement of spallation target for the fuel handling process, the principle of collision detection based on the fast ray-casting technology, the real-time roaming experience with feedback control in refueling procedure, and the reliability assessment and sequential optimization for the above process. The spallation target and fuel handling system can cover all the assemblies in subcritical reactor and provide a powerful tool for the frequently updated engineering design of the CiADS project.

In order to make preparations for the follow-up kinetic behavior studies, we construct a deterministic model for the lead core of the VENUS-II facility, and carry out some analyses of the static neutronics characteristics. In the modeling processes, we apply the so-called Cell-Based-Assemblies method to generate the group constants using the Monte-Carlo models, for which, several difficulties induced by the complex materials, the special neutron spectrum and space distribution in this reactor are overcome. The effective multiplication factors, the space distribution and the energy group distribution of the neutron flux driven by the fixed source at a sub-critical mode are compared with the Monte-Carlo results. At the same time, we have analyzed the influence of different energy group structures, different discrete directions and different transport calculation methods. The results show that, except for the 8-group structure, the parameters obtained by the deterministic method are in good agreement with the results of the Monte-Carlo method.

This paper systematically investigates the dynamic behavior of stay cables with passive negative stiffness dampers (NSD) installed close to the cable end. A passive NSD is modeled as a combination of a negative stiffness spring and a viscous damper. Through both analytical and numerical approaches, parametric analysis of negative stiffness and viscous damping are conducted to systematically evaluate the vibration control performance of passive NSD on stay cables. Since negative stiffness is an unstable element, the boundary of passive negative stiffness for stay cables to maintain stability is also derived. Results reveal that the asymptotic approach is only applicable to passive dampers with positive or moderate negative stiffness, and loses its accuracy when a passive NSD possesses significant negative stiffness. It has been found that the performance of passive NSD can be much better than those of conventional viscous dampers. The superior control performance of passive NSD in cable vibration mitigation is validated through numerical simulations of a full-scale stay cable.