中性束诊断系统中高压电源的保护分析

介绍了DNB中所必需的电源系统，着重介绍了加速极电源的结构、功能及工作原理，设计了相应的保护电路。仿真和实验结果表明它们对系统的安全运行提供了可靠的保障。     

Feasibility of a specialized ground light source for night-time low-light calibration

The day/night band (DNB) of the Visible Infrared Imaging Radiometer Suite can not only identify surface characteristics when illuminated by moonlight, but can also detect night-time radiation from ground active light sources. Accordingly, the low-light sensor can be calibrated by comparing upward active radiation with actual observed digital counts, which has attracted new research interest. In this article, the first attempt to calibrate the high-gain stage of the DNB using a specialized ground light source was introduced. The DNB imaging rule of the target pixel at various observation geometries was analysed based on the long-term monitoring of a light source set in Dunhuang, Gansu Province, China. The radiance caused by emissive radiation varied greatly over time in a 16-day cycle. To solve the major problem of the Dunhuang light source when used for low-light calibration, a light source that emits homogenous radiation intensity in most upward directions was custom designed. Based on this device, a comprehensive low-light calibration scheme was proposed and three verification experiments were performed in Mingguang, Anhui Province, China. The predicted in-band DNB at-aperture radiance values of the 3-day experiments were 3.86 × 10^?9, 4.38 × 10^?9, and 5.27 × 10^?9 W cm^?2 sr^?1, respectively, while the actual observed DNB radiance values were 4.53 × 10^?9, 5.06 × 10^?9, and 5.57 × 10^?9 W cm^?2 sr^?1, respectively. With deviations of 14.8%, 13.4%, and 5.4%, respectively, the calibration result based on the specialized light source was generally in good agreement with the operational calibration result, and thus the feasibility of the device for low-light calibration had been preliminarily verified.     

CL-20/DNB共晶炸药的制备与表征

采用溶液共结晶法制备得到一种由六硝基六氮杂异伍兹烷(HNIW,俗称CL-20) 和1,3-二硝基苯(DNB)组成的新型共晶炸药,其中CL-20与DNB的摩尔比为1:1。粉末X射线衍射表明共晶炸药的衍射图谱明显不同于构成它的两个单组份;单晶X射线衍射测试结果表明,该共晶炸药属正交晶系,Pbca空间群,晶胞参数：a =0.94703(6) nm,b =1.34589(8) nm,c =3.3620(2) nm,α=β=γ=90?,V=4.2852(5) nm 3, Z=8;差示扫描量热（DSC）法分析表明,CL-20/DNB共晶炸药在188~268℃间放热分解,熔点较DNB提高约45℃左右。     

DNB后过渡沸腾传热计算模型

提出过渡沸腾传热的物理模型,建立相应的数学模型,对偏离泡核沸腾(DNB)后过渡沸腾的传热特性进行分析。根据实验数据确定关系式中的系数,得到DNB后过渡沸腾传热计算模型。将提出的理论计算模型与现有不同工况范围内取得的实验数据及已有计算模型进行比较分析,并对计算偏差进行统计计算。结果表明,本文模型计算值与现有实验数据符合良好;相对于已有计算模型,模型具有良好的适用性。     

Failure Mechanism of Silicide and Aluminide Fuels During Power Transient

The quantitative failure mechanism of the silicide and aluminide fuels (the test specimens) was studied using the 4.8 g/cc silicide fuels as the references. (1) The onset of the departure from the nucleate boiling (DNB) was determined to be 188 ± 27°C for the test specimens and 182 ± 15°C for the references. The difference was insignificant. (2) The failure mechanism of both fuels was attributed to the quench stress that occurred owing to the uneven temperature profile across the fuel plate. In-core quantitative data indicated that when the temperature drop ΔT was greater than 94°C and the time to quench tq was shorter than 0.13 s, through-plate cracking could occur. (3) Irrespective of the fuel initial density, the plate bow increased with an increase in the PCST. The worst bow up to 228°C (JRR-3 operational limit) was 15%.     

A review on the clad failure studies

In this paper, an attempt has been made to systematically organize the research investigations conducted on clad tube failure, so far. Before presenting the review on the clad failure studies, an introduction to different clad materials has been added, in which the effect of alloying elements on the material properties have been presented. The literature on clad failure has been broadly categorized under the headings LOCA and RIA. The failure mechanisms like creep, corrosion and pellet-clad interaction have been discussed in details. Each subsection of the review has been provided with summary table, in which the studies are arranged in the chronological order. A small section on acceptance criteria for ECCS has also been included. The last section of the review has been dedicated to the core-degradation phenomena.     

Experimental Study on Heat Transfer Characteristics of Vertical 5×5 Heated Rod Bundles around Critical Pressure with R-134a

With the aim of researching the heat transfer characteristics around the critical pressure in rod bundle geometry, the behaviors of the heating surface temperatures at the vertical 5×5 heated rod bundles with R-134a were experimentally investigated under both pressurizing and depressurizing processes, where the pressure constantly decreases from supercritical to subcritical and constantly increases from subcritical to supercritical under constant inlet thermal conditions. As the pressure approaches the critical pressure, a DNB type or a dryout type of CHF was induced, and then the post-CHF was kept until the vicinity of the critical pressure. Under the supercritical pressure, the post-CHF disappeared due to the extinction of boiling phenomena, but the heat transfer deterioration was induced in a certain pressure range. In the depressurizing process, the heating surface temperatures followed the trajectory of temperature behaviors as in the pressurizing process except for the quenching point. The quenching point from the post-CHF moved to the lower pressure side than the pressure as for the CHF in the pressurizing process. This phenomenon was considered as the hysteresis phenomenon frequently observed in pool boiling curve characteristics.     

编码器在黄骅港三期翻车系统中的应用

随着工业自动化程度和性能的提高,编码器作为速度、位置、角度或计数的传感器应用范围越来越广。主要介绍编码器在黄骅港三期翻卸系统中的应用,其中包括增量式编码器与变频器之间的网络架构、绝对值编码器与DNB模块之间的连接方式,并提出一种改进的PLC编码器数值监控算法。     

共晶和共混对CL-20/DNB感度和热解机理影响的MD模拟

为了从分子水平进一步揭示共晶和共混对六硝基六氮杂异伍兹烷(CL-20)/1,3-二硝基苯(DNB)含能材料的感度、力学性能和热解机理的影响,采用分子动力学(MD)模拟方法在COMPASS力场条件下对CL-20、DNB、两者的共混物及共晶的感度、结合能和力学性能进行了模拟计算。在Reax FF/lg力场条件下对其热解机理进行了研究。结果表明,共晶和共混均会降低体系的感度,但共晶效果更加明显;与共混物结构相比,共晶结构更加稳定,共晶和共混均可以改变复合体系的力学性能,降低体系的刚度,增加体系的柔性和安全性,但共混会使体系的力学性能劣化。共晶分子间强的作用会促进体系中各组分的热解反应,NO_2、N_2、NO、H_2O、HONO、HON以及CO_2等是共晶和共混体系的主要热解产物。与共混相比,共晶是一种更加有效的含能材料改性方法,可为含能材料的配方设计提供理论指导。     

Safety analysis of LBLOCA in BDBA scenarios for the Bushehr's VVER-1000 nuclear power plant

This paper presents the results of thermal-hydraulic calculations of a large break loss of coolant accident (LBLOCA) analysis for a VVER-1000/V446 unit at Bushehr nuclear power plant (BNPP). LBLOCA is analysis in two different beyond design basis accident (BDBA) scenarios using the RELAP5/MOD3.2 best estimate code. The scenarios are LBLOCA with station blackout (SBO) and LBLOCA with pump re-circulation blockage which have been evaluated in the final safety analysis report (FSAR) of BNPP. A model of VVER-1000 reactor based on Unit 1 of BNPP has been developed for the RELAP5/MOD3.2 thermal-hydraulics code consists of 4-loop primary and secondary systems with all their relevant sub-systems important to safety analysis. The analysis is performed without regard for operator's actions on accident management. The safety analysis is carried out and the results are checked against the acceptance criteria which are the possibility of using water inventory in the emergency core cooling system (ECCS) accumulators and the KWU tanks for core cooling and the available time to operators before the maximum design limit of fuel rod cladding damage is reached. These kinds of analyses are performed to provide the response of monitored plant parameters to identify symptoms available to the operators, timing of the loss of critical safety functions and timing of operator actions to avoid the loss of critical safety functions of core damage. The results of performed analyses show that the operators have 2.9 and 3.1 h for LBLOCA with SBO and LBLOCA with pump re-circulation blockage scenarios, respectively, before the fuel rod cladding rupture. The results are also compared with the BNPP FSAR data.