The accurate prediction of neutron flux and reactor power is very important for the safe operation of the reactor immediately after the disturbance of reactor parameters. The traditional method combining POD and Galerkin projection has the problem of low accuracy due to cumulative error. In this study, the implicit difference method is used to obtain the exact solution of one-dimensional neutron spatiotemporal diffusion. As the reference data, two LSTM neural network terms are introduced to eliminate the cumulative error and truncation error of POD, and to build a hybrid drive model driven by physics and data. The results show that the root-mean-square error of neutron flux, total power and each order modal coefficient is reduced by 1-2 orders of magnitude after adding the neural network correction term, and the calculation time is significantly reduced under the same order of prediction when the neural network extension term is added. The improved model based on 2nd and 3rd order scaling to 6th order is 13% and 7.6% faster than the original 6th order model, respectively. The hybrid drive model can improve the rapid prediction accuracy of POD, and the results have certain reference value.
A three-dimensional numerical calculation was carried out on the departure from nucleate boiling (DNB) type critical heat flux (CHF) in a vertical circular tube under different rolling conditions. The Euler two-phase flow model and the non-equilibrium wall boiling model were used. By comparing the simulated CHF values of static tubes with experimental values, a sensitivity analysis of different wall boiling sub-models was completed. The CHF of a vertical tube with sinusoidal simple harmonic rolling motion is predicted for 15 combinations of amplitude and period. The results show that all rolling conditions lead to the early occurrence of DNB. In the most "violent" rolling situation, the value of CHF is the smallest. The temperature and heat transfer coefficient in the tube will change periodically with the rolling motion. Within a period, larger amplitude and smaller period will cause the heating wall to have a smaller heat transfer coefficient at a certain moment, resulting in an increase in the maximum temperature of the wall. This study can provide a reference for the numerical prediction of DNB-type CHF under rolling conditions.
Efficient thermionic energy conversion technology is the key technology for improving the thermoelectric conversion efficiency of thermionic fuel elements and promoting the space thermionic reactor power supply towards higher power and longer lifetime. To explore the key factors that improve the efficiency of thermionic energy conversion, this article starts from the basic principle of thermionic energy conversion and summarizes the methods to improve the thermoelectric conversion efficiency of thermionic fuel elements from three aspects: improvement of the emitter, improvement of the collector, and reduction of arc voltage drop. Analysis shows that the clear direction for significantly improving thermoelectric conversion efficiency is the improvement of the collector, and the key is the development of a new generation of low absorption cesium work function collector materials.
As a typical valve in primary system, manual globe valve is of great importance to maintain system operation and protect system safety. In order to verify the action reliability of the nuclear-grade manual globe valve and determine its operation state accurately and quantitatively, this paper studies and establishes an integrated intelligent operation device for manual globe valve action test, and proposes a method for identifying the state of the manual globe valve based on the combination of wavelet packet decomposition and support vector machine (SVM). Firstly, the torque signal is employed as the characteristic curve and the wavelet packet decomposition technique is utilized to extract the time-frequency domain features. The time domain and time-frequency domain features are integrated to construct the hybrid feature vector. Secondly, the Principal Component Analysis (PCA) is used to perform the dimensionality reduction analysis on the feature vectors to obtain fault feature vectors. Finally, the support vector machine (SVM) method is employed to identify the action state of valve. The results shows that the device constructed in this study solves the problems of long time-consuming and low efficiency in verifying the reliability of manual globe valve actions, as well as the difficulty in quantifying the evaluation of the action process. The proposed method can identify the three action states of the valve accurately and efficiently.
In order to meet the growing demand for low-carbon heating and improve the operational flexibility and economic benefits of the heating system, a nuclear heating system (DHGHS) integrating a "Yanlong" pool-type low-temperature heating reactor (DHR-400), a heat storage pool, and a gas boiler was proposed. A central heating region in Liaoyuan City was taken as the application scenario of DHGHS, the equipment capacity and operation optimization with the goal of minimizing the annual cost were carried out. A comparison between DHGHS and four heating schemes including DHR-400 and heat storage pool, DHR-400 and gas boiler, gas boiler, and ground source heat pump was conducted. The results show that the heat storage pool with a rated volume of 3.15×105 m3 and the gas boiler with a rated capacity of 82.79 MW can achieve the flexible operation of DHGHS throughout the heating period. The total number of power adjustments of DHR-400 in the whole heating period is only 177 times. The optimal annual cost of DHGHS is RMB 1.16×108, which is lower than the other four heating schemes. The optimal heating scale of DHGHS is 1.18×107 m2. The work in this paper can provide theoretical guidance for the design and operation optimization of the multi-heat source nuclear heating system.
The design characteristics of ACP100 make the radiation steaming become one of the radiation protection problems that need to be paid attention to, and it is necessary to carry out targeted shielding design. In order to improve the accuracy of discrete ordinates method in small modular reactor modeling calculation, a visual modeling plug-in of discrete ordinate method based on the code NX is developed in this study, which can directly define all attributes in NX graphical interface, and automatically complete meshing to form a complete calculation input. In this study, the radiation streaming calculation of ACP100 is completed based on the visual modeling technology and the self-developed three-dimensional discrete ordinates transport calculation code Hydra, and a special shielding module is set for the radiation streaming problem, which greatly reduce the thermal neutron flux in the main pump room and the radiation dose of the operating platform.
Radioisotope thermoelectric generator is a device that converts the thermal energy produced by the decay of radioactive isotopes into electric energy. It involves the strong coupling of thermal-electric physical fields and is difficult to simulate accurately. In this paper, based on a 90Sr Radioisotope thermoelectric generator prototype, firstly, the digital simulation model of the direct coupling of thermal-electric physical fields of the prototype is established, and the model parameters are optimized by combining the experimental data. Then, the accuracy of the model simulation under the steady and dynamic operation of the prototype is verified by simulation tests. Finally, the thermal-electric field analysis of the whole prototype and the output power research with different load resistance are carried out by using the model. The results show that the heat leakage of the prototype system accounts for 26% and the electric energy loss of the circuit is 10% under given operating conditions. Under the best matching load resistance, the maximum output power of the whole prototype can reach 96 mW, and the thermoelectric conversion efficiency is 2%.
主要介绍了我国在建、在运核电机组的基本状况和最新进展,以及我国在提升核设施安全水平方面的相关措施。在国家能源局印发的《能源技术创新“十三五”规划》要求之下,我国推出一系列先进核能和小型堆的发展计划,开展了“海洋核动力平台示范工程建设”并建立相关标准。最后总结了中国核电目前面临的挑战和未来的展望。
热管冷却反应堆采用固态反应堆设计理念,通过热管非能动方式导出堆芯热量。本文总结了热管冷却反应堆的概念初创、积极探索、重大突破的发展历程;分析了热管冷却反应堆的技术特点,包括固态属性、固有安全性高、运行特性简单、易于模块化与易扩展和运输特性良好等核心优势;归纳了热管冷却反应堆中热管性能、材料工艺、能量转换等技术现状,并提出热管冷却反应堆进一步发展将面临的材料、制造工艺、运行可维护性等挑战,从而明确了热管冷却反应堆未来的发展趋势,为革新型热管冷却反应堆技术的发展与应用提供良好的方向指引。总体而言,热管冷却反应堆在深空探测与推进、陆基核电源、深海潜航探索等场景中具有广阔的应用前景,有可能成为改变未来核动力格局的颠覆性技术之一。
放射性废液得到有效处理是世界各国核工业迅猛发展的前提,其关键技术的现状和发展方向也是我国核工业界关注的焦点。本文介绍了几种放射性废液处理的传统方法及涌现出的新技术,概述了各种方法的原理及优、缺点,同时讨论了放射性废液处理技术今后的研究方向及发展趋势。
以配置四取中逻辑输入模块的核电厂稳压器数字压力控制装置为研究对象,建立其故障树模型,包括四取中逻辑的动态部分和其他设备的静态部分,采用马尔科夫方法分析动态部分,再根据逻辑关系分析整体故障树,最后,围绕可靠度和重要度评价四取中逻辑的可靠性及其对整个装置可靠性的提升效果,结果表明:四取中逻辑在可靠性方面优化程度相对较高。
“华龙一号”是我国自主设计研发的具有完整知识产权的第三代百万千瓦级压水堆核电技术。本文介绍了“华龙一号”的产生历程,系统论述了“华龙一号”反应堆堆芯与安全设计特点,包括“华龙一号”研发过程中开展的堆芯核设计、热工水力设计、安全设计、设计验证及“华龙一号”持续开展的设计改进与优化等内容,通过采用新的设计理念和设计技术,全面提高了“华龙一号”作为三代核电技术的经济性、灵活性和安全性。
为解决核电厂传统监测手段的局限性,提出将核主元分析法(KPCA)引入核电厂设备在线监测领域中,并设计了监测模型建设方法以及在线监测策略。为验证算法的有效性,将其应用在国内某核电机组电动主给水泵的真实监测案例中。仿真结果表明,KPCA算法可适应核电厂设备监测的要求,能比现有阈值监测手段提供更为早期的故障预警。同时,相比于常规的主元分析法(PCA),KPCA算法能够提取各变量之间的非线性关系,识别出设备不同的运行模式,有效减少误报警。
为提高已投入运行核动力装置旋转设备的运行数据采集和状态监测能力,需要解决安装传感器和敷设配套线缆困难的问题。本文采用现场可编程门阵列(FPGA)作为主控单元,设计了一种基于Zigbee物联网通信技术的智能无线振动传感器,并给出了其电路构成、工作原理,以及嵌入式控制软件的工作流程。通过对此传感器进行性能测试,结果表明该传感器功耗低,实现了对振动信号的连续采集、智能分析与上传。该无线传感器安装简单,无需敷设供电和信号线缆,可应用于构建核动力装置旋转设备的状态监测系统。
为分析核电厂应急人员在处理严重事故时可能发生的人因失误,通过建立不同应急人员的认知模型及识别相应的行为影响因子,在认知功能的基础上识别出13种人因失误模式:信息来源不足、信息可靠性不佳、过早结束对参数的获取、重要数据处理不正确、缓解措施负面影响评估失误、选择不适用当前情景的策略、延迟决策、遗漏重要信息/警报、延迟发觉、软操作失误、信息反馈失效、设备安装/连接/操作失误、延迟实施,并基于故障树分析得出人因失误模式的主要根原因:交流失效、时间压力、事故发展的不确定性、信息接收延误、监视失误、人-机界面不佳和环境因素。分析结果可用于预测严重事故缓解进程中可能出现的人因失误,为核电厂实施严重事故管理和技术改进,以及保障严重事故工况下核电厂安全提供参考。
介绍了中广核研究院在事故容错燃料(ATF)包壳领域的最新成果,通过预置粉末式脉冲激光熔覆技术,在不同的功率下制备出不同厚度的锆包壳管Cr保护层;通过高温蒸汽氧化增重数据发现,采用半导体脉冲激光熔覆技术、脉冲激光功率50~60 W、螺距0.8~0.9 mm、角速度10°/s等参数条件下制备Cr涂层可以获得较好的抗高温氧化性能,证明保护的效果直接受涂层质量控制。通过SEM分析了涂层的显微结构,采用扩散机理解释了Cr涂层在1200℃下与锆合金基体相容性良好的原因。
采用计算流体动力学(CFD)方法对Z字形通道的印刷电路板式换热器(PCHE)的热工水力特性进行了研究,结合物性拟合公式和用户自定义函数(UDF)计算超临界CO2物性;湍流模型采用SST k-ω模型,通过摩擦阻力系数和传热系数的实验数据对方法进行了验证。模拟结果表明,流体在弯折点处,加速核心区域向外侧壁靠近;在弯折点下游,存在较大压降,且随分离流的减弱而减小。