252Cf中子活化核燃料棒235U富集度检测设备的软件设计

介绍了252Cf中子活化核燃料棒235U富集度检测设备的软件设计,该软件采用多线程技术控制研华PCI-1780采集卡定时采集六路探测器输出的经252Cf中子活化后235U裂变产物的γ射线信号,针对采集数据的特性,进行相应的处理和分析,可以检测出核燃料棒的实际235U富集度以及有无异常芯块.该软件经过实验验证在检测速度为6时,能够准确测量核燃料棒的实际235U富集度值并判断棒中是否混有异常芯块,同时向PLC发送相应信号实现自动分选.目前已应用在核燃料元件厂的核燃料棒235U富集度无损检测设备上.     

新一代核燃料棒UO2芯块间隙检测设备研制

在原来核燃料棒UO2芯块间隙无损检查仪的基础上,改进了γ射线准直器结构和物理测量仪器,提高了241Am放射性活度(3.7GBq),使检测速度由原来的1.5m/min,提高到10 m/min,可检测最小间隙为0.4mm,测量精度为±0.048 mm,置信概率为95%.采用新方法检测弹簧空腔长度,并增加了多定标测量道数,使弹簧空腔长度的检测精度为±0.947mm,置信概率为95%.该设备是以核技术为中心的机电一体化产品,具有自动上料、自动分选、自动下料等全自动控制功能.     

~(137)Cs源燃料棒芯块间隙检测装置设计

设计了一种使用~(137)Csγ放射源检测新型燃料棒内芯块间隙的装置。该装置除具备241Am源检测装置功能外,还可清晰辨别实心芯块和环形芯块区域,以及辨别燃料棒内的芯块垫、弹簧、支撑管等。使用1.5Ci的~(137)Cs放射源,装置检测速度6 m/min、置信度95%时,设备的燃料棒长度检测精度为4mm/1m,间隙检测精度为±0.13 mm。装置运行稳定性良好,精度满足检测需求。     

新型无源法核燃料棒~(235)U富集度检测系统研制

介绍了新型无源法核燃料棒~(235)U富集度检测系统的研制,该系统采用4通道多探测器设计,能在核燃料棒匀速通过检测体时有效探测核燃料芯块中~(235)U核素自发衰变产生的γ射线,实时生成~(235)U富集度分布图谱,进而判断各通道核燃料棒质量是否合格并实现好坏料自动分选。该系统经实验验证在单通道检测速度为1 m/min时,能够准确测量核燃料棒~(235)U富集度值并判断棒中是否混有异常芯块。该系统已应用于核燃料元件生产线上。     

核电站燃料元件UO_2芯块间隙无损检查仪

介绍了核电站燃料元件UO_2芯块的间隙无损检查仪。采用~(241)Amγ射线透射法,可以准确地检查出元件中芯块间隙的大小及位置。放射源活度为1.11×10~9Bq(30mCi),检查速度为1.5m/min时,可以准确地检查出最小间隙为0.4±0.05mm,置信度为95％。在间隙W_i≥1.3mm和0.5mm≤W_i≤1.3mm的间隙累计量ΣW_i≥7.6mm时,仪器发出判废信号,从而对元件棒实现自动分检。     

核燃料棒芯块235U丰度检测方法研究

核燃料棒中UO₂芯块的²³⁵U丰度检测是保证核反应堆正常运行的重要环节,根据铀样品能谱谱形,通过迭代拟合算法精确选取目标信号的能量范围,减少了测量精度受UO₂芯块年龄的影响,扩大了目标信号能量选取范围,基于小波变换法,过滤无关频率信号,提高了突变信号的识别精度,进一步提高了检测速度。通过模拟存在异常丰度芯块燃料棒检测验证了方法的可行性。     

芯块年龄对燃料棒富集度检测的影响研究

为保证核电站运行安全,反应堆装入核燃料组件的²³⁵U富集度具有严格的设计要求。因此,反应堆燃料棒均必须经过100%富集度及装料均匀性无损检测。已有富集度检测包括有源法和无源法,通过对有源法、无源法两种富集度检测方法中UO₂芯块年龄现象的研究,发现有源检测法在较低活度下,受UO₂芯块年龄影响,使得燃料棒富集度无法正确检测,需采用被动放置等待的方式解决芯块年龄问题。无源法可在检测中直接校正芯块年龄,满足生产检测要求,已得到工程化应用。     

核电站燃料元件UO_2芯块间隙无损检查仪

介绍了核电站燃料元件UO_2芯块的间隙无损检查仪。采用~(241)Am γ射线透射法,可以准 确地检查出元件中芯块间隙的大小及位置。放射源活度为1.11×10~9Bq(30mCi),检查速度为1.5m/min时,可以准确地检查出最小间隙为0.4±0.05mm,置信度为95％。在间隙W_i≥1.3mm和0.5mm≤W_i≤1.3mm的间隙累计量∑W_i≥7.6mm时,仪器发出判废信号,从而对元件棒实现自动分检。     

实时成像应用于燃料辐照后检验技术研究

X光照相是燃料辐照后检验的一项基本检验内容。X光照相用以观察燃料棒内部燃料芯块堆积情况，主要观察燃料芯块与芯块间的间隙、燃料芯块与包壳间间隙、燃料芯块堆积高度、燃料芯块开裂情况及压紧弹簧松弛情况。燃料芯块开裂及其间隙的变化会引起反应堆内中子通量分布变化，     

高速无源燃料棒235U富集度检测设备研制

高速无源燃料棒²³⁵U富集度检测设备采用小型化模块化BGO+SiPM探测器串列及集成了放大、甄别、信号采集、网络传输、I/O功能的多通道核电子仪器组成检测体,设计恒温箱对检测体温度进行精准控制,通过燃料棒传输及上下料装置完成燃料棒²³⁵U富集度及棒内富集度异常芯块的全自动检测。设备具有良好的芯块年龄校正功能。测试表明,单通道96只探测器检测速度6 m/min时,富集度检测精度优于2.1%,对基体富集度3.4%、富集度偏差8.73%的异常芯块检出率为70%,检测置信度95%。     

Scaling of the Density Peak with Pellet Injection in ITER

Scalings of the density peak and pellet penetration length in ITER are developed based on simulations using 1.5D BALDUR integrated predictive modeling code. In these simula- tions, the pellet ablation is described by the Neutral Gas Shielding (NGS) model with grad-B drift effect taken into account. The NGS pellet model is coupled with a plasma core transport model, which is a combination of an MMM95 anomalous transport model and an NCLASS neoclassical transport model. The BALDUR code with a combination of MMM95 and NCLASS models, together with the NGS model, is used to simulate the time evolution of plasma current, ion and electron temperatures, and density profiles for ITER standard type I ELMy H-mode discharges during the pellet injection. As a result, the scaling of the density peak and pellet penetration length at peak density can be established using this set of predictive simulations that covers a wide range of ITER plasma conditions and pellet parameters. The multiple regression technique is utilized in the development of the scalings. It is found that the scaling for density at center is sensitive to both the plasma and pellet parameters; whereas the scalings for density and location of the additional peak are sensitive to the pellet parameters only.     

Indirect estimation method of the turbulence induced fluid force spectrum acting on a fuel rod

This paper proposes a methodology to identify a turbulent flow induced force acting on a nuclear fuel rod based on the indirect input force estimation theory in structural dynamics, which is useful to predict the forcing function when the input force cannot be measured directly. Since the nuclear fuel rod in a PWR (pressurized water reactor) is exposed to coolant flow, the turbulence induced force generates a fuel rod vibration which may cause a fretting wear on the surface of the rod. This study develops a method to estimate turbulence induced force spectrum indirectly for a real scale fuel rod loaded in a nuclear fuel test facility. The proposed method requires a reliable finite element (FE) model which simulates the fuel rod dynamics well; therefore, the FE model is discussed, especially regarding the procedure to determine the effective rod density. Since the pellets rattle inside the tube due to small gaps between the tube and pellets, especially at the beginning of the fuel's life, the contribution of the pellet mass to the density for the FE model cannot be determined clearly. It is shown that the appropriate density can be estimated by comparing the natural frequencies from the modal test results of the rod (with pellet) and the tube (without pellet). Then, the indirect turbulence induced force estimation theory is applied to the fuel rod, and some numerical and test results are discussed to verify the applicability of the suggested method.     

Development of the pellet injection system on the J-TEXT tokamak

Pellet injection is an attractive technology for core-fueling and magnetohydrodynamic study in magnetic-confinement fusion devices like tokamaks and stellarators. It can inject solid hydrogen/deuterium pellets into the plasma with deeper density deposition compared with other fueling methods, such as gas puffing. A three-barrel H₂ pellet injection system was installed on the J-TEXT tokamak and experiments were carried out. The pellets are formed in three barrels cooled by a cryocooler and compressor system at around 9 K, and are 0.8 mm/1 mm diameter and 0.8 mm length. The pellet is launched by helium propellant gas and injected from the low-field side of the plasma. The normal range of pellet speed is 210–310 m s⁻¹ for different propellant gas pressures. Due to the three-barrel structure, the number of injected pellets can be adjusted between one and three. Pellets can be launched sequentially with arbitrary time intervals, which enables flexible applications. The results of the experiments show that pellet fueling efficiency can reach 50%. The energy confinement time increased by about 7.5‒10 ms after pellet injection.     

乏燃料贮存格架流固耦合参数的数值模拟

乏燃料贮存格架是储存乏燃料组件的重要设备。在地震载荷下,其响应是非线性的,可能产生滑移、颠覆等。发生地震时,存在于格架间隙内的流体耗散了结构的能量,保证了格架的完整性。本文使用3/10缩比模型,利用CFD软件Fluent进行了乏燃料贮存格架2D瞬态分析。计算过程中利用动网格方法模拟格架强迫振动,并进行了参数不确定性分析。利用CFD瞬态流体力分别获得了双Ⅱ区、双Ⅰ区格架附加质量矩阵。利用同轴圆柱体附加质量的计算解与解析解进行对比验证,证明了本文计算方法的准确性。本文计算所得的附加质量矩阵可为乏燃料贮存格架结构动态软件提供流固耦合参数。     

Cladding Deformation due to Gas Bubble Swelling of UO2 Pellet in Bump Test

Fission gas release in the bump tests was correlated to the deformations of claddings via mathematical product of the number of gas atoms and their residing time on grain boundaries. A positive correlation of the deformations with the product indicated that gas bubble swelling of pellets contributed to the pellet-cladding mechanical interaction (PCMI).

Residual gaps prior to the bump tests turned out to be filled in at the bump terminal level by differential thermal expansion of pellet and cladding. Visible macro cracks existing in the central part of the pellet virtually vanished during the tests due to bubble swelling of the pellet. Together with these observations, quantitative image analysis of pellet porosity showed that the aforementioned PCMI was brought about by combination of differential thermal expansion and bubble swelling.

A model to unify gas release, bubble growth and PCMI simulated well the observed behaviors of fission gas release from bump-tested rods. It was deduced by the model that higher burnup retains a higher potential for PCMI, while power reductions and associated gas releases reduce PCMI.

In the analysis in this paper were used the data of the Rise Transient Fission Gas Release Project.     

Interaction of Impurity （Li, Be, B and C） and Hydrogen Isotope Pellet Injection with Reactor-relevant Plasmas

Based on the two-dimensional kinetic ablation theory of the hydrogen pellet ablation developed by Kuteev [B.V. Kuteev, Nuclear Fusion, 35 (1995) 431], an algorithm of erosion speed and ablation rate calculations for Li, Be, and B impurity pellets in reactor-relevant plasma has been derived. Results show compatibilities of lithium pellet injection used in α-particle diagnostics are positive in comparison with other solid impurity pellets (e.g. Be, B and C). Using the 2-D Kuteev lentil model, including kinetic effects, we find that currently existing pellet injection techniques will not meet core-fueling requirements for ITER-FEAT. A pressure as high as 254 MPa must be applied to a pellet accelerator with a 200 cm-long single-stage pneumatic gun, in order to accelerate a pellet with a radius rpo = 0.5 cm to a velocity of vpo, 24 × 105 cm/s penetrating 100 cm into the ITER plasma core. Comparisons of pellet velocity- and radius-dependent penetration depth between the Neutral Gas Shielding and the Kuteev's     

低水平光激中子探测装置

光激中子由~(226)Ra γ源发射的γ量子轰击氘靶产生,由~3He正比管阵列组成的高灵敏中子—中子甄别探测器记录,给出计算氘靶内氘含量的信息。该装置主要用于含氘部件氘含量的无损测定。     

小丸内靶靶丸跟踪系统工作原理及相关测试

小丸内靶靶丸跟踪系统是小丸内靶装置的一套辅助测量系统,该系统用于测量靶丸在反应点的位置和时间信息,记录每个靶丸的飞行轨迹和时间,配合其他靶丸控制系统实现反应事例顶点的精确定位,精确度能达到几十μm量级。本文描述了小丸内靶靶丸跟踪系统的工作原理,即利用靶丸对光的散射收集该散射光定位靶丸所在位置,及该系统搭建前的部分测试工作,确定了该系统的最终结构,即相机与光源的夹角为135°,确定了光源为5.5mW的激光;测定了线扫描相机频率为98.000 8kHz和镜头M7528-MP最小物距为285mm,此时放大倍率为0.224。     

HJ9000核辐射环境监测车

核辐射环境监测车是核电站运行的必备外围监测设备,它可以对核电站周围不同方向不同地点进行流动监测,并能对某些感兴趣点随时随地进行采样监测.本文介绍了核辐射环境监测车的基本配置、应用领域及当今的发展趋势.并详细介绍了HJ9000核辐射监测车的设计思想、基本功能和主要技术指标.并着重论述了该车采用卧式弹簧减震的实验与数据.计算机做总控单元的特点及丰富的软件资源.