Preliminary electromagnetic analysis of the COOL blanket for CFETR

The supercritical CO_(2)cOoled Lithium-Lead(COOL)blanket has been designed as one advanced blanket candidate for the Chinese Fusion Engineering Test Reactor(CFETR).This work focuses on the electromagnetic(EM)loads(Maxwell force and Lorentz force)acting on the COOL blanket,which are important mechanical loads in further structural analysis of the COOL blanket.A 3D electromagnetic analysis is performed using the ANSYS finite element method to obtain EM loads on the COOL blanket in this study.At first,the magnetic scalar potential(MSP)method is used to obtain the magnetic field and the Maxwell force on the COOL blanket.Then,the magnetic vector potential(MVP)method is performed during a plasma disruption event to get the eddy current distribution.At last,a multi-step method is adopted for the calculation of the Lorentz force and the torque.The maximum Lorentz forces of inboard and outboard blanket structural components are 5624 kN and 2360 kN respectively.

Neutronics analysis of a subcritical blanket system driven by a gas dynamic trap-based fusion neutron source for ^(99)Mo production

Gamma-emitting radionuclide ^(99m)Tc is globally used for the diagnosis of various pathological conditions owing to its ideal single-photon emission computed tomography (SPECT) characteristics.However,the short half-life of ^(99m)Tc (T_(1/2)=6 h)makes it difficult to store or transport.Thus,the production of ^(99m)Tc is tied to its parent radionuclide ^(99)Mo (T_(1/2)=66 h).The major production paths are based on accelerators and research reactors.The reactor process presents the potential for nuclear proliferation owing to its use of highly enriched uranium (HEU).Accelerator-based methods tend to use deuterium–tritium(D–T) neutron sources but are hindered by the high cost of tritium and its challenging operation.In this study,a new ^(99)Mo production design was developed based on a deuterium–deuterium (D–D) gas dynamic trap fusion neutron source (GDT-FNS) and a subcritical blanket system (SBS) assembly with a low-enriched uranium (LEU) solution.GDT-FNS can provide a relatively high-neutron intensity,which is one of the advantages of ^(99)Mo production.We provide a Monte Carlo-based neutronics analysis covering the calculation of the subcritical multiplication factor (k_(s)) of the SBS,optimization design for the reflector,shielding layer,and ^(99)Mo production capacity.Other calculations,including the neutron flux and nuclear heating distributions,are also provided for an overall evaluation of the production system.The results demonstrated that the SBS meets the nuclear critical safety design requirement (k_(s)<0.97) and maintained a high ^(99)Mo production capacity.The proposed system can generate approximately 157 Ci ^(99)Mo for a stable 24 h operation with a neutron intensity of 1×10^(14) n/s,which can meet 50%of China’s demand in 2025.

Joint target assignment and power allocation in the netted C-MIMO radar when tracking multi-targets in the presence of self-defense blanket jamming

The netted radar system(NRS)has been proved to possess unique advantages in anti-jamming and improving target tracking performance.Effective resource management can greatly ensure the combat capability of the NRS.In this paper,based on the netted collocated multiple input multiple output(CMIMO)radar,an effective joint target assignment and power allocation(JTAPA)strategy for tracking multi-targets under self-defense blanket jamming is proposed.An architecture based on the distributed fusion is used in the radar network to estimate target state parameters.By deriving the predicted conditional Cramer-Rao lower bound(PC-CRLB)based on the obtained state estimation information,the objective function is formulated.To maximize the worst case tracking accuracy,the proposed JTAPA strategy implements an online target assignment and power allocation of all active nodes,subject to some resource constraints.Since the formulated JTAPA is non-convex,we propose an efficient two-step solution strategy.In terms of the simulation results,the proposed algorithm can effectively improve tracking performance in the worst case.

Feasibility to Convert the NuScale SMR from UO2 to a Mixed (U, Th)O2 Core: A Parametric Study of Fuel Element—Seed-Blanket Concept

Delays in the construction of nuclear reactors due to licensing issues have been a problem across the world, affecting projects in Finland, France, and the United States. Small Modular Reactors (SMRs) emerge as a transition between Generations III+ and IV in order to make nuclear energy more competitive with other energy sources, including renewables. In this study, the SMR NuScale, one of the most promising projects today, is investigated for its conversion into a U-233-producing reactor through the Radkowsky seed-blanket fuel element concept, applied in the Shippingport reactor, in a parametric study. Initially, a validation of the reference reactor (NuScale) was carried out with data from technical documents and papers, thus demonstrating the agreement of the computational model carried out with the SERPENT code. Then, a parametric study is carried out to define the area of the seed and blanket region, proportions of enrichment and pitch length. Finally, a comparison is made between the production of U-233, TRU reduction, burn-up extension and neutronic and thermohydraulic safety parameters. This study demonstrates an improvement in the conversion factor and a considerable reduction in the production of TRU, in addition to the production of U-233 with a low proportion of other uranium isotopes that can lead to the beginning of the thorium cycle with already consolidated technologies.

一种近似Markov Blanket最优特征选择算法

特征选择可以有效改善分类效率和精度,传统方法通常只评价单个特征,较少评价特征子集.在研究特征相关性基础上,进一步划分特征为强相关、弱相关、无关和冗余四种特征,建立起Markov Blanket理论和特征相关性之间的联系,结合Chi-Square检验统计方法,提出了一种基于前向选择的近似Markov Blanket特征选择算法,获得近似最优的特征子集.实验结果证明文中方法选取的特征子集与原始特征子集相比,以远小于原始特征数的特征子集获得了高于或接近于原始特征集的分类结果.同时,在高维特征空间的文本分类领域,与其它的特征选择方法OCFS,DF,CHI,IG等方法的分类结果进行了比较,在20Newsgroup文本数据集上的分类实验结果表明文中提出的方法获得的特征子集在分类时优于其它方法.

基于Markov blanket和互信息的集成特征选择算法

针对大量无关和冗余特征的存在可能降低分类器性能的问题,提出一种基于近似Markov blanket和动态互信息的特征选择算法并将其应用于集成学习,进而得到一种集成特征选择算法。该集成特征选择算法运用Bagging方法结合提出的特征选择方法生成基分类器,并引入基分类器差异度进行选择性集成,最后用加权投票法融合所选基分类器的识别结果。通过仿真实验验证算法的有效性,以支持向量机(support vector machine,SVM)为分类器,在公共数据集UCI上进行试验,并与单SVM及经典的Bagging集成算法和特征Bagging集成算法进行对比。实验结果显示,该方法可获得较高的分类精度。

基于Markov blanket的无约束型K阶贝叶斯集成分类模型

为了提升K阶依赖贝叶斯分类(KDB)模型的条件依赖表达能力,本文以Markov blanket的特征提取思想为基本原则,降低特征属性间的条件独立性,根据贪婪搜索策略进行贝叶斯分类模型的结构学习。基于训练样本集构建宏观模型,基于测试样本构建微观模型,最终通过集成模型进行决策。针对UCI机器学习数据集进行交叉验证,实验结果分别从0-1损失、偏差和方差等角度证明了本文算法的合理性和有效性。

基于近似Markov Blanket和动态互信息的特征选择算法

针对大量无关和冗余特征的存在可能降低分类器性能的问题,提出了一种基于近似Markov Blanket和动态互信息的特征选择算法。该算法利用互信息作为特征相关性的度量准则,并在未识别的样本上对互信息进行动态估值,利用近似Markov Blanket原理准确地去除冗余特征,从而获得远小于原始特征规模的特征子集。通过仿真试验证明了该算法的有效性。以支持向量机为分类器,在公共数据集UCI上进行了试验,并与DMIFS和ReliefF算法进行了对比。试验结果证明,该算法选取的特征子集与原始特征子集相比,以远小于原始特征规模的特征子集获得了高于或接近于原始特征集合的分类结果。

Progress on design and related R&D activities for the water-cooled breeder blanket for CFETR

The water-cooled ceramic breeder (WCCB) blanket is one of the blanket candidates for Chinese fusion engineering testing reactor (CFETR) and is being developed at the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). This paper reviews design and evolution of the WCCB blanket for CFETR, and presents a new WCCB blanket design according to the latest CFETR core parameters (major and minor radii are R = 7.2 m and a = 2.2 m, respectively) and missions. This new design is expected to satisfy multiple CFETR operation modes of 0.2, 0.5, 1.0, and 1.5 GW fusion power and achieve tritium self-sufficiency. The feasibility of the updated blanket design is evaluated from the aspects of neutronics and thermo-hydraulics. Furthermore, the research and development (R&D) activities supporting to the WCCB blanket for CFETR are reported, including the design code, the water loop experiments, the pebble bed modeling and experiments, and the components fabrication technology.

Existence detection of blanket jamming based on fractal characteristics in FRFT domain

This paper addresses the existence detection of blanket jamming based on fractal features in fractional Fourier transform （FRET） domain. Firstly, the existences of fractal features of three typical jamming signals are analyzed, and box dimension and information dimension are employed to describe fractal features quantitatively. Then the differences of fractal characteristics between blanket jamming and white Gaussian noise （WGN） in FRFT domain are described, and a detector to detect the jamming is proposed. At last, simulations are done to verify that the algorithm is effective preferable.

Considering for the blanket structure scheme of HCCB DEMO

For the solid blanket concept of helium cooled ceramic breeder (HCCB) demonstration fusion power plant (DEMO), a feasible blanket structure with configuration 2×X is proposed as considering relatively low temperature limit of neutron multiplier beryllium pebbles. Based on that, preliminary design for the typical blanket module of HCCB DEMO has been carried out and verified by thermal-hydraulic analysis and structural analysis. Furthermore, the specific relationship of maximum temperature depended on the surface heating of blanket key part first wall (FW) is also analyzed.

Direct simulation of MHD flows in dual-coolant liquid metal fusion blanket using a consistent and conservative scheme

Direct simulation of 3-D MHD(magnetohydrodynamics) flows in liquid metal fusion blanket with flow channel insert(FCI) has been conducted.Two kinds of pressure equilibrium slot (PES) in FCI,which are used to balance the pressure difference between the inside and outside of FCI,are considered with a slot in Hartmann wall or a slot in side wall,respectively.The velocity and pressure distribution of FCI made of SiC/SiC_f are numerically studied to illustrate the 3-D MHD flow effects,which clearly show that t...

Core and blanket thermal-hydraulic analysis of a molten salt fast reactor based on coupling of OpenMC and OpenFOAM

In the core of a molten salt fast reactor(MSFR),heavy metal fuel and fission products can be dissolved in a molten fluoride salt to form a eutectic mixture that acts as both fuel and coolant.Fission energy is released from the fuel salt and transferred to the second loop by fuel salt circulation.Therefore,the MSFR is characterized by strong interaction between the neutronics and the thermal hydraulics.Moreover,recirculation flow occurs,and nuclear heat is accumulated near the fertile blanket,which significantly affects both the flow and the temperature fields in the core.In this work,to further optimize the conceptual geometric design of the MSFR,three geometries of the core and fertile blanket are proposed,and the thermal-hydraulic characteristics,including the three-dimensional flow and temperature fields of the fuel and fertile salts,are simulated and analyzed using a coupling scheme between the open source codes OpenMC and OpenFOAM.The numerical results indicate that a flatter core temperature distribution can be obtained and the hot spot and flow stagnation zones that appear in the upper and lower parts of the core center near the reflector can be eliminated by curving both the top and bottom walls of the core.Moreover,eight cooling loops with a total flow rate of0.0555 m3 s-1 ensur an acceptable temperature distribusure an acceptable temperature distribution in the fertile blanket.

Unsupervised feature selection based on Markov blanket and particle swarm optimization

Feature selection plays an important role in data mining and recognition, especially in the large scale text, image and biological data. Specifically, the class label information is unavailable to guide the selection of minimal feature subset in unsupervised feature selection, which is challenging and interesting. An unsupervised feature selection based on Markov blanket and particle swarm optimization is proposed named as UFSMB-PSO. The proposed method seeks to find the high-quality feature subset through multi-particles' cooperation of particle swarm optimization without using any learning algorithms. Moreover, the features' relevance will be computed based on an information metric of relevance gain,which provides an information theoretical foundation for finding the minimization of the redundancy between features. Our results on several benchmark datasets demonstrate that UFSMB-PSO can achieve significant improvement over state of the art unsupervised methods.

Effects of uniconazole rate on agronomic traits and physiological indexes of rapeseed blanket seedling

Mechanized transplanting of rapeseed(Brassica napus L.)blanket seedling is an innovative cultivation technology.Cultivating high quality blanket seedling to ensure high survival rate of seedling after transplanting is the key of the technology.The effects of different uniconazole rates of 0,0.5,1.0,1.5 and 2.0 mg/tray,spraying at one leaf and one heart stage,on selected agronomic traits,physiological indexes and survival rate of two rapeseed cultivars(‘Qinyou 100 and’Yangyou 90)were investigated in 2018 and 2019.Our results showed that the plant height decreased significantly with the increase of uniconazole rate.However,the collar diameter increased significantly with the increase of uniconazole rate up to 1.5 mg/tray,and the leaf area,dry weights of root and shoot increased with increased uniconazole rate up to 1.0 mg/tray.The root to shoot ratios,N concentrations of root and shoot with the uniconazole rates of 1.0 and 1.5 mg/tray were higher than those with other treatments.As uniconazole rate increasing,gibberellin(GA)and auxin(IAA)concentrations of root and shoot decreased,while abscisic acid(ABA)concentrations increased,and cytokinin(CTK)concentrations topped at uniconazole rate of 1.0 mg/tray and decreased thereafter.The seedling survival rates with 1.0 and 1.5 mg/tray were greatly higher than those in other treatments.Regression analysis suggested plant survival rate was positively related to CTK concentrations and negatively to GA concentrations of root and shoot.To achieve high survival rate after mechanized transplanting,our study revealed that the uniconazole applied at a rate of 1.0 mg/tray was recommended as the best,followed by 1.5 mg/tray.The findings would help to enhance qualities of rapeseed blanket seedling and to promote popularization of mechanized transplanting of rapeseed production.

Protection of Environment from Damaged Nuclear Station and Transparent Inflatable Blanket for Cities—Protection from Radioactive Dust and Chemical, Biological Weapons

The author, in a series of previous articles, designed the “AB Dome” made of transparent thin film supported by a small additional air overpressure for the purpose of covering a city or other important large installations or sub-regions. In present article the author offers a variation in which a damaged nuclear station can be quickly covered by such a cheap inflatable dome. By containing the radioactive dust from the damaged nuclear station, the danger zone is reduced to about 2 km2 rather than large regions which requires the resettlement of huge masses of people and which stops indus-try in large areas. If there is a big city (as Tokyo) near the nuclear disaster or there is already a dangerous amount of radioactive dust near a city, the city may also be covered by a large inflatable transparent Dome. The building of a gi-gantic inflatable AB Dome over an empty flat surface is not difficult. The cover is spread on a flat surface and a venti-lator (fan system) pumps air under the film cover and lifts the new dome into place but inflation takes many hours. However, to cover a city, garden, forest or other obstacle course in contrast to an empty, mowed field, the thin film cannot be easily deployed over building or trees without risking damage to it by snagging and other complications. This article proposes a new method which solves this problem. The design is a double film blanket filled by light gas such as, methane, hydrogen, or helium - although of these, methane will be the most practical and least likely to leak. Sections of this AB Blanket are lighter than air and will rise in the atmosphere. They can be made on a flat area serving as an as-sembly area and delivered by dirigible or helicopter to station at altitude over the city. Here they connect to the already assembled AB Blanket subassemblies, cover the city in an AB Dome and protect it from bad weather, chemical, bio-logical and radioactive fallout or particulates. After assembly of the dome is completed, the light gas can be replaced by (heavier but cheaper) air. Two projects for Tokyo (Japan) and Moscow (Russia) are used in this paper for sample computation.

Numerical Analyses of Electromagnetic Forces on the ITER Blanket Module Shield Block During Major Disruptions

Electromagnetic(EM) load is one of the key design drivers for the blanket shield block(SB) and other in-vessel components. In this article, an EM analysis method was developed to address the EM force on the SB. The plasma currents, which vary spatially and temporally,are loaded as a filament at each time point. The standard blanket module No.04(BM04) under major disruption(MD) is selected to perform the analyses. The analyses results are validated by comparing currents on the passive structure. To better understand the effects of cooling channels and slits on the EM force, the case of SB without cooling channel and the case without slits are calculated to make comparisons. The results show that the slits play an important role in controlling the EM load on SB.

Comparative studies for two different orientations of pebble bed in an HCCB blanket

The Indian Test Blanket Module(TBM) program in ITER is one of the major steps in its fusion reactor program towards DEMO and the future fusion power reactor vision. Research and development(R&D) is focused on two types of breeding blanket concepts: lead–lithium ceramic breeder(LLCB) and helium-cooled ceramic breeder(HCCB) blanket systems for the DEMO reactor. As part of the ITER-TBM program, the LLCB concept will be tested in one-half of ITER port no. 2, whose materials and technologies will be tested during ITER operation. The HCCB concept is a variant of the solid breeder blanket, which is presently part of our domestic R&D program for DEMO relevant technology development. In the HCCB concept Li_2TiO_3 and beryllium are used as the tritium breeder and neutron multiplier, respectively, in the form of a packed bed having edge-on configuration with reduced activation ferritic martensitic steel as the structural material. In this paper two design schemes, mainly two different orientations of pebble beds, are discussed. In the current concept(case-1), the ceramic breeder beds are kept horizontal in the toroidal–radial direction. Due to gravity, the pebbles may settle down at the bottom and create a finite gap between the pebbles and the top cooling plate, which will affect the heat transfer between them. In the alternate design concept(case-2), the pebble bed is vertically(poloidal–radial) orientated where the side plates act as cooling plates instead of top and bottom plates. These two design variants are analyzed analytically and 2 D thermal-hydraulic simulation studies are carried out with ANSYS, using the heat loads obtained from neutronic calculations.Based on the analysis the performance is compared and details of the thermal and radiative heat transfer studies are also discussed in this paper.

Preliminary performance analysis and optimization based on 1D neutronics model for Indian DEMO HCCB blanket

India,under its breeding blanket R&D program for DEMO,is focusing on the development of two tritium breeding blanket concepts;namely the lead-lithium-cooled ceramic breeder and the helium-cooled ceramic breeder(HCCB).The study presented in this paper focuses on the neutronic design analysis and optimization from the tritium breeding perspective of the HCCB blanket.The Indian concept has an edge-on configuration and is one of the variants of the helium-cooled solid breeder blanket concepts proposed by several partner countries in ITER.The Indian HCCB blanket having lithium titanate(Li2TiO3)as the tritium breeder and beryllium(Be)as the neutron multiplier with reduced-activation ferritic/martensitic steel structure aims at utilizing the low-energy neutrons at the rear part of the blanket.The aim of the optimization study is to minimize the radial blanket thickness while ensuring tritium self-sufficiency and provide data for further neutronic design and thermal-hydraulic layout of the HCCB blanket.It is found that inboard and outboard blanket thicknesses of 40 cm and 60 cm,respectively,can give a tritium breeding ratio(TBR)>1.3,with 60%6Li enrichment,which is assumed to be sufficient to cover potential tritium losses and associated uncertainties.The results also demonstrated that the Be packing fraction(PF)has a more profound impact on the TBR as compared to 6Li enrichment and the PF of Li2TiO3.

Application of Tencel on Raschel Blanket

For excellent properties,Tencel is more and more popular in textile industry.Four kinds of raschel knitted blanket test samples were woven with the base-weave polyester yarns and velvet yarns,respectively including pure Tencel,Tencel/polyacrylonitrile,pure polyester,and pure polyacrylonitrile.The style of samples was evaluated with the ranking evaluation method,and its warmth retention,compressibility,antistatic properties and so on were tested.Fuzzy comprehensive was applied to the evaluation of comprehensiveness.The result shows that Tencel fiber can improve the appearance style of raschel blanket,and alter the thermal-wet comfort properties and antistatic properties.And the blanket fabric contained Tencel is durable and not dilapidated easily.But the raschel blanket used pure Tencel velvet yarn has poor properties.Compared with traditional raschel blanket,the blanket blended with Tencel/polyacrylonitrile improves a certain degree on comprehensive properties.So Tencel has certain value in acrylic knitted blanket.