ADS散裂靶件内部自由界面形态的数值模型分析

加速器驱动的次临界系统（ADS）内部的散裂靶件通过加速器装置耦合次临界堆芯。无窗靶件的设计需保证自由界面有着稳定且理想的形状，以避免液态重金属局部过热。为研究无窗靶件内部自由界面的形态，本工作基于开源CFD计算平台OpenFOAM，使用VOF（volumeoffluid）方法追踪自由界面，对无窗靶件内部自由界面的形态和特性进行数值模拟，并将结果与商用软件FLUENT计算结果和实验结果进行对比。同时比较多种湍流模型对计算的影响，推荐出较合适的湍流模型。     

ADS无窗靶件自由界面模拟实验和数值研究

冷却剂自由界面形态的形成和控制是加速器驱动的次临界系统(ADS)无窗靶件设计的关键技术之一。采用水介质对无窗靶件模型的自由界面特征进行了实验和数值研究。实验中采用激光诱导荧光的示踪方法实现了流场的可视化,得到Re=30000～50000范围内的自由界面和可视化流场。在高Re工况下,流场中出现大尺度的非稳定涡结构,随着Re的降低,流场中涡结构的紊乱程度增加。分别采用大涡模型（LES）和两方程动能-特征耗散率模型（kω-SST）对无窗靶件实验工况进行了数值分析,计算结果表明,LES能较好地模拟实验中所得的流场现象和界面特征。     

基于水工质的有窗散裂靶流场分析及实验测量

散裂靶是加速器驱动的次临界系统(ADS)的重要组成部分,有窗散裂靶是唯一经实验验证、测量的液态金属高功率散裂靶,研究有窗靶内工质的流动对散裂靶的设计优化有重要意义。本文以水为工质对有窗靶件进行了可视化实验及数值模拟研究,实验采用粒子图像测速法对靶件可视化部分进行速度场测量,同时利用计算流体力学软件FLUENT对靶件流场进行数值模拟。通过5种湍流模型（标准k-ε模型、RNG k-ε模型、Realk-ε模型、SST k-ω模型、RSM模型）在不同流速下的模拟结果与实验结果的对比分析,表明采用RNG k-ε模型并结合相应的壁面函数能较准确模拟有窗靶内的流动。     

ADS无窗靶件流场结构和自由界面数值模拟研究

自由界面流动现象是加速器驱动次临界系统(ADS)无窗靶件研究的重要组成部分。采用计算流体动力学(CFD)方法,对上海交通大学设计的无窗靶件流道结构中的自由界面流动水力学行为进行数值模拟研究。数值模拟使用FlUENT软件平台,采用体积流体法(VOF)与界面追踪方法结合湍流大涡模型(LES),进行Re在35000⁸0000工况下的非稳态计算。模拟结果得到了自由界面稳定性、自由界面宽度、大尺度漩涡结构、漩涡滞止区长度和锥形段流道沿程压力随Re变化的规律。     

基于扩散界面法的ADS无窗散裂靶自由界面数值研究

采用水作为模拟工质,用扩散界面法和有限元法以及k-ε湍流模型对无窗靶件的自由界面非稳态特性进行数值模拟。结果和实验吻合较好,表明扩散界面法能准确地进行模拟,并且结果表明流场中存在一个回流区以及中心线沿程压力存在一个谷值和峰值。通过计算不同出口背压下的自由界面的形状和高度,获得出口压力对界面稳定性的影响,同时计算不同出口背压对回流区长度的影响以得到增大无窗靶的热移出能力的规律,结果表明:出口背压在900Pa以上,自由界面较稳定,不会产生明显的气泡,出口背压越大,自由界面越稳定,高度越高;同时,出口背压越大,回流区的高度越低,热移出能力越强。     

液态金属镓回路搭建及无窗靶实验研究

液态金属回路是开展液态金属散裂靶关键技术与实验验证的必备实验平台。镓具有较低的熔点、非常高的沸点,且无毒性,可在液态金属回路实验中作为模拟介质使用。本文介绍了一套小型液态金属镓回路的设计思路、结构组件、基本功能及使用流程,给出了液态镓在变频离心泵驱动下强制对流的流量、压力、压差及无窗靶自由液面位置和形态的实验测量结果,并分析了压力、压差及自由液面位置随流量的变化关系。结果表明,无窗靶自由液面位置主要由流体压力和流速决定。     

加速器驱动系统靶区流场的数值模拟

在加速器驱动系统（ADS）中,真空质子束流管出口端为一半球面质子束窗,用于隔离束流管和散裂靶。质子束窗表面热负荷很高,有效冷却质子束窗,从而提高靶件寿命和系统安全性是靶件设计的关键。 采用PHOENICS 3.2程序对ADS靶件冷态下的流场进行数值模拟。在贴体坐标（BFC）下生成计算网格,对靶件束窗下方有无导流板时的靶区流场进行了计算。当体积流量为10m3/h时,流体向下流动进入中央流道（靶区）之前发生边界层脱离,并在质子束窗下方两侧形成一对对称的旋涡。两旋涡在靶区中央重叠,形成一股向上较强的回流。这股回流沿质子束窗     

PDS-XADS散裂靶热工水力分析

本文对小型加速器驱动的次临界系统（ADS）--PDS-XADS散裂靶进行了热工水力分析。分析的XADS型实验堆基于欧洲PDS-XADS实验项目的设计,使用铅铋合金（LBE）作为冷却剂。散裂靶是ADS的核心部件之一,用以确保反应堆功率维持在指定水平。本文利用计算流体力学软件ANSYS CFX 11.0对散裂靶的下部区域进行热工水力分析。分析采用稳态计算、剪切应力输运（SST）湍流模型,在壁面边界条件处采用自动壁面函数法,针对不同的散裂靶设计进行计算流体力学（CFD）分析,最后根据散裂靶设计限值选择最优设计方案。     

加速器驱动的次临界系统散裂靶热工水力研究

散裂靶位于加速器驱动的次临界系统（ADS）的中心,为核嬗变提供所需的中子源。通过分析散裂靶的热工要求,选取铅铋合金（LBE）作为ADS的靶材料和冷却剂。使用MCNP程序计算质子束轰击靶区产生的能量沉积,并使用CFD程序FLUENT计算靶区热工特性。分析了不同设计参数及不同靶窗形状对ADS靶区温度分布和速度分布的影响,得到满足热工要求的可选方案。     

加速器驱动的次临界系统散裂靶泄漏中子谱研究

为研究加速器驱动的次临界系统（ADS）散裂靶的散裂中子学特性,采用Geant4计算不同能量质子轰击铅铋靶产生的泄漏中子产额、能谱、轴向积分分布。模拟得到1 GeV质子对应的靶的优化尺寸及优化后泄漏中子谱,计算结果可为ADS散裂靶件和堆芯设计提供参考。     

WEBEXPIR: Windowless target electron beam experimental irradiation

The windowless target electron beam experimental irradiation (WEBEXPIR) program was set-up as part of the MYRRHA/XT-ADS R&D effort on the spallation target design to investigate the interaction of a proton beam with a liquid lead-bismuth eutectic (LBE) free surface. In particular, possible free surface distortion or shockwave effects in nominal conditions and during sudden beam on/off transient situations, as well as possible enhanced evaporation were assessed. An experiment was conceived at the IBA TT-1000 Rhodotron, where a 7 MeV electron beam was used to simulate the high power deposition at the MYRRHA/XT-ADS LBE free surface. The geometry and the LBE flow characteristics in the WEBEXPIR set-up were made as representative as possible of the actual situation in the MYRRHA/XT-ADS spallation target. Irradiation experiments were carried out at beam currents of up to 10 mA, corresponding to 40 times the nominal beam current necessary to reproduce the MYRRHA/XT-ADS conditions. Preliminary analyses show that the WEBEXPIR free surface flow was not disturbed by the interaction with the electron beam and that vacuum conditions stayed well within the design specifications.     

XT-ADS Windowless spallation target thermohydraulic design & experimental setup

The objective of the European 6th framework Integrated Project (IP) EUROTRANS (EUROpean Research Programme for the TRANSmutation of High Level Nuclear Waste in an Accelerator Driven System) is to demonstrate the feasibility of transmutation of high level nuclear waste using subcritical Accelerator Driven Systems (ADS). The spallation target represents the most challenging new component in an ADS since it is the component coupling the accelerator and the nuclear core and is subjected to very high thermal load in a high radiation field. In this document the thermal hydraulic activities which led to reliable design rules for a windowless target are presented and the status of the heavy liquid metal target mock-up experiment at the KArlsruhe Liquid metal LAboratory (KALLA) are reported.     

ADS熔盐散裂靶中子学性能研究

与传统加速器驱动次临界系统（ADS）采用金属靶作为散裂中子靶的设计不同,加速器驱动次临界熔盐堆（AD-MSRs）采用靶堆一体的设计,直接使用燃料熔盐作为散裂中子靶。由于熔盐靶的中子学性能直接影响AD MSRs的能量放大系数、核废物的嬗变和核燃料增殖的效率,所以本研究基于MCNPX程序,详细计算了高能质子轰击氟盐和氯盐两种熔盐靶产生的散裂中子产额、散裂中子能谱、能量沉积分布以及散裂产物等中子学性能,并与液态Pb和铅铋共熔体（LBE）两种液态金属靶进行了对比。计算结果表明,熔盐靶在散裂中子产额上与液态金属靶有一定的差距,但熔盐靶内能量沉积分布的梯度较小,更有利于靶区的热量导出。与液态Pb和LBE靶相比,熔盐靶的散裂产物中包含更多的气体以及高质量数的α发射体核素。     

Three-dimensional CFD simulations to study the effect of impeller geometry on internal flow field in ADS upward spiral flow target

The relationship between flow field characteristics and geometrical structures is an important issue in designing liquid metal spallation target for accelerator-driven sub-critical system (ADS). Upward spiral flow target (USFT) is a new type ADS windowless target in which an impeller is employed to generate upward spiral flow and regulate internal flow field. The impeller comprises a central shaft and several identical blades, and its geometry is very crucial for designing the target. In this paper, series models with different geometric parameters of the shaft and the blades are simulated by ANSYS CFX to analyse the distributions of internal flow field and the dimensions of stagnation zone in USFT. The results show that the shaft plays a primary role in guiding the upward flow while the blades are significant for generating the spiral flow. Finally, an optimized model with preferred geometric parameters is obtained by comparing the overall simulation results. The whole research has foundational signification for further studying USFT.     

活化法测量散裂靶中子能谱的实验验证

散裂靶中子的能谱对加速器驱动次临界系统的倍增因数和嬗变率等影响很大,计算表明散裂靶中子谱在MeV能区与裂变中子谱相近。本文利用活化法测量临界装置的泄漏中子谱和中子注量率,提出了用In、Al、Mg、Ti、Au、Zn、Ni、Rh、Fe和Co等活化箔测量散裂靶中子能谱和中子注量率的方案。结果表明,将活化箔在散裂靶中子场中辐照5h,中子注量最高达5×1014 cm-2量级,辐照后1h内取出活化箔,根据半衰期的长短安排测量顺序,可测量散裂靶的中子能谱和中子注量率。     

MYRRHA: A European Experimental ADS for R&D Applications Status at Mid-2005 and Prospective towards Implementation

Since 1998, SCK?CEN, Mol, Belgium,—in partnership with many European research laboratories—is designing a multipurpose Accelerator Driven System for R&D applications—MYRRHA. In parallel, an associated R&D support program is being conducted. MYRRHA aims to serve as a basis for the European experimental ADS providing protons and neutrons for various R&D applications. It consists of a LINAC proton accelerator delivering a 350MeV*5mA proton beam to a windowless liquid Pb-Bi spallation target that, in turn, couples to a Pb-Bi cooled, sub-critical fast core of 50MW thermal power. In this paper, we report on the status of the MYRRHA project at mid-2005 and the prospective towards its future implementation.