Two types of a passive safety containment for a near future BWR with active and passive safety systems

The paper presents two types of a passive safety containment for a near future BWR. They are named Mark S and Mark X containment. One of their common merits is very low peak pressure at severe accidents without venting the containment atmosphere to the environment. The PCV pressure can be moderated within the design pressure. Another merit is the capability to submerge the PCV and the RPV above the core level. The third merit is robustness against external events such as a large commercial airplane crash. Both the containments have a passive cooling core catcher that has radial cooling channels. The Mark S containment is made of reinforced concrete and applicable to a large power BWR up to 1830 MWe. The Mark X containment has the steel secondary containment and can be cooled by natural circulation of outside air. It can accommodate a medium power BWR up to 1380 MWe. In both cases the plants have active and passive safety systems constituting in-depth hybrid safety (IDHS). The IDHS provides not only hardware diversity between active and passive safety systems but also more importantly diversity of the ultimate heat sinks between the atmosphere and the sea water. Although the plant concept discussed in the paper uses well-established technology, plant performance including economy is innovatively and evolutionally improved. Nothing is new in the hardware but everything is new in the performance.     

A feasibility assessment of the use of nanofluids to enhance the in-vessel retention capability in light-water reactors

Nanofluids, colloidal dispersions of nanoparticles, exhibit a substantially higher critical heat flux (CHF) compared to water. As such, they could be used to enhance the in-vessel retention (IVR) capability in the severe accident management strategy implemented by certain light-water reactors. It is envisioned that, at normal operating conditions, the nanofluid would be stored in dedicated storage tanks, which, upon actuation, would discharge into the reactor cavity through injection lines. The design of the injection system was explored with risk-informed analyses and computational fluid dynamics. It was determined that the system has a reasonably low failure probability, and that, once injected, the nanofluid would be delivered effectively to the reactor vessel surface within seconds. It was also shown analytically that the increase in decay power removal through the vessel using a nanofluid is about 40%, which could be exploited to provide a higher IVR safety margin or, for a given margin, to enable IVR at higher core power. Finally, the colloidal stability of a candidate alumina-based nanofluid in an IVR environment was experimentally investigated, and it was found that this nanofluid would be stable against dilution, exposure to gamma radiation, and mixing with boric acid and lithium hydroxide, but not tri-sodium phosphate.     

基于 PCCS 色彩体系的 ASD 儿童干预 APP 配色研究

为提升自闭症谱系障碍(ASD)儿童干预 APP 的康复效果,为设计师提供合理有效的参考,提出 一种基于 PCCS 色彩体系的 ASD 儿童干预 APP 界面配色评价方法。首先通过文献分析和焦点小组法,构建基 于 PCCS 色彩体系的 ASD 儿童干预 APP 界面配色评价体系;其次运用 AHP 法获取各项评价指标的权重;再 次筛选得到 8 个基于 PCCS 色彩体系的界面配色设计方案,邀请专家对其打分,得到初始评判矩阵;然后通过 TOPSIS 法获得各方案的排序结果;最后对结果进行解析。研究表明,ASD 儿童对绿色、蓝色等冷色调及明度、 纯度较高的色彩具有较高的认可度;在 PCCS 色调图中,ASD 儿童更喜爱轻柔色调、浅色调、邻近色与互补色 的搭配;在界面配色设计中应更趋于明快、清晰、和谐、稳重的色彩搭配。将该评价方法应用于干预 APP 界 面配色实验方案评价中,可以提高设计评价过程中的客观性、科学性,为设计师进行决策提供参考,更好地促 进 ASD 儿童干预 APP 的发展。     

Analysis of different containment models for IRIS small break LOCA, using GOTHIC and RELAP5 codes

Advanced nuclear water reactors rely on containment behaviour in realization of some of their passive safety functions. Steam condensation on containment walls, where non-condensable gas effects are significant, is an important feature of the new passive containment concepts, like the AP600/1000 ones.In this work the international reactor innovative and secure (IRIS) was taken as reference, and the relevant condensation phenomena involved within its containment were investigated with different computational tools. In particular, IRIS containment response to a small break LOCA (SBLOCA) was calculated with GOTHIC and RELAP5 codes. A simplified model of IRIS containment drywell was implemented with RELAP5 according to a sliced approach, based on the two-pipe-with-junction concept, while it was addressed with GOTHIC using several modelling options, regarding both heat transfer correlations and volume and thermal structure nodalization. The influence on containment behaviour prediction was investigated in terms of drywell temperature and pressure response, heat transfer coefficient (HTC) and steam volume fraction distribution, and internal recirculating mass flow rate. The objective of the paper is to preliminarily compare the capability of the two codes in modelling of the same postulated accident, thus to check the results obtained with RELAP5, when applied in a situation not covered by its validation matrix (comprising SBLOCA and to some extent LBLOCA transients, but not explicitly the modelling of large dry containment volumes).The option to include or not droplets in fluid mass flow discharged to the containment was the most influencing parameter for GOTHIC simulations. Despite some drawbacks, due, e.g. to a marked overestimation of internal natural recirculation, RELAP5 confirmed its capability to satisfactorily model the basic processes in IRIS containment following SBLOCA.     

基于Pareto熵的多目标粒子群优化算法

粒子群优化算法因形式简洁、收敛快速和参数调节机制灵活等优点,同时一次运行可得到多个解,且能逼近非凸或不连续的Pareto最优前端,因而被认为是求解多目标优化问题最具潜力的方法之一.但当粒子群优化算法从单目标问题扩展到多目标问题时,Pareto最优解集的存储与维护、全局和个体最优解的选择以及开发与开采的平衡等问题亦随之出现.通过目标空间变换方法,采用Pareto前端在被称为平行格坐标系统的新目标空间中的分布熵及差熵评估种群的多样性及进化状态,并以此为反馈信息来设计进化策略,使得算法能够兼顾近似Pareto前端的收敛性和多样性.同时,引入格占优和格距离密度的概念来评估Pareto最优解的个体环境适应度,以此建立外部档案更新方法和全局最优解选择机制,最终形成了基于Pareto熵的多目标粒子群优化算法.实验结果表明：在IGD性能指标上,与另外8种对等算法相比,该算法在由ZDT和DTLZ系列组成的12个多目标测试问题集中表现出了显著的性能优势.     

Toward the biomimetic implant surface: Biopolymers on titanium-based implants for bone regeneration

Replacing malfunctioning tissues with titanium-based implants has become a widespread practice spurred by population aging. Advances in biomaterials, technology and implantation protocols have led to increasing expectations on the applicability and durability of implants. The field has recently moved from a bioinert to a bioactive paradigm due to surface modifications that trigger specific responses on the surrounding tissues. Biopolymeric surface coatings have taken up a central role in these developments. The use of these and other biomimetic strategies on implants provides greater control over material–cell interactions and it is aimed at improving long-term clinical results by replicating some of the structures and mechanisms of living tissues. This review summarizes the state of the art of biomimetic implants and discusses the main directions and challenges of this field toward a more predictable and successful implant osseointegration.     

Proposal for selecting two‐color combinations with various affections. Part II: Demonstration of the system

The characteristics of the proposed color selection system are shown using several colored figures of two‐color combinations selected by the system. There are four kinds of color feelings in the system, and each feeling is classified into three categories (i.e., high, intermediate, or low). The feelings used are pleasantness, contrast, floridness, and warmth. Users can try the 3⁴ = 81 combinations of feelings by setting the categories for four kinds of feelings. The differences among categories of color feelings are also shown by several colored figures. It is difficult to describe the differences by words. However, it is rather easy to describe by pictures. The proposed color selection system is expected to be a useful tool for assisting color designers. Comments about the proposed system from potential users are reported. © 2009 Wiley Periodicals, Inc. Col Res Appl, 34, 135–140, 2009     

Delayed-feedback artificial neural network applied in multi-parameters thermal-hydraulic system performance assessing: An integral PCCS test case-study

For validating the safety of the new design of large passive nuclear plant, a series of thermal-hydraulic(T-H) test facilities were set up by SNPTRD. The T-H performance of passive containment cooling system was deeply researched by the sub-scaled modeling integral test system – CERT, according to scaling-analysis method. Besides of traditional T-H methods, we had tried applying ANN to simulate the performance of CERT, which is a multi-parameters system. The ANN is adapted from a Feed-Forward Back-Propagation network with delayed output feed-back. Two different networks were set up for the steady-state and transient case respectively. A directly Monte Carlo(M.C.) selecting procedure was generated to achieve a set of optimized weights of the networks. After the circulatory calculation of ANN combined with M.C., 9311 samples were calculated for a specific steady-state case. The minimum value for the largest bias is 2.4%. For transient case, two tests of different steam-injection conditions were studied. After 1e5 samples, the maximum bias for simulating two transient cases can be limited at 10.7%, and 17.9% respectively.     

基于灰色聚类法的老年人APP用户界面配色评价研究

目的 对老年人APP用户界面配色进行评价.方法 首先采用文献研究与焦点小组法,构建老年人APP用户界面配色评价体系;其次采用层次分析法(AHP)来确定APP用户界面配色评价体系中各评价指标的相对权重;接着根据市场调研与用户访谈的结果,与PCCS色彩体系相结合制作实验样本;然后使用灰色聚类法对实验观测值进行灰色聚类得到聚类系数,并由得到的聚类系数对聚类对象进行聚类;最后根据聚类结果对实验样本进行分类并进行结果分析.结论 本文以老年人医疗 APP 用户界面配色作为研究案例,结果验证了基于灰色聚类法的老年人APP用户界面配色评价方法的可行性与有效性.     

基于威斯康辛冷凝试验本体的结构改进及分析

先进压水堆(APWR)是第三代核电技术的代表堆型之一,它采用了非能动安全系统,提高了安全性能。非能动安全壳冷却系统(PCCS)主要利用蒸汽的冷凝来带走安全壳内的热量。本文主要介绍了威斯康辛大学进行的冷凝试验的试验本体结构,应用ANSYS软件对其结构进行了应力分析,并在现有结构的基础上对外部加强筋布置进行了一定的改进和优化。通过计算和比较可以看出,经过改进后的加强筋布置,不仅满足原有的试验要求,结构布置合理,更提高了试验本体的承压能力,使其能够满足更高试验压力的需要。