共查询到18条相似文献,搜索用时 250 毫秒
1.
反应堆中各结构部件的抗辐照性能,对整个系统的使用寿命及安全性有较大的影响。本工作通过MCNPx2.70蒙特卡罗软件建立CiADS散裂靶次临界反应堆模型,结合NJOY2016核数据截面处理软件制作的材料原子离位截面,在堆芯组件数分别为30,42,72盒的情况下分别计算和分析了316L、15-15Ti、SIMP 3种不锈钢材料和ZTA陶瓷作为候选结构材料的中子辐照损伤情况。当用作CiADS燃料包壳时,3种不锈钢材料中SIMP制成的包壳的Rdpa值最小,在燃料组件数为30,42,72盒的情况下其年辐照损伤量分别约为1.16,1.61和12.0 dpa/a。而ZTA制成的燃料包壳的Rdpa值均大于不锈钢材料的辐照损伤。在散裂靶次临界反应堆耦合区域,轴向上CiADS中心管在束靶作用面附近所受到的辐照损伤最大。燃料组件数为30盒时,由316L制成的中心管的辐照损伤率峰值约为2.7 dpa/a。 相似文献
2.
3.
高能质子在散裂靶中的能量沉积是散裂靶中子学研究的重要内容之一,准确掌握高能质子在散裂靶中引起的能量沉积分布与瞬态变化是开展散裂靶热工流体设计的重要前提.本文采用MCNPX,PHITS与FLUKA三种蒙特卡罗模拟程序,计算并比较了高能质子入射重金属铅靶、钨靶的能量沉积分布及不同粒子对总能量沉积的占比贡献;针对高能质子入射金属钨靶的能量沉积实验数据空白,采用热释光探测器阵列测量了250 MeV质子束入射厚钨靶的能量沉积分布,实验结果表明蒙特卡罗模拟程序在散裂靶中能量沉积的计算结果具有较高的可靠性. 相似文献
4.
5.
6.
加速器驱动次临界系统(ADS)液态Pb-Bi散裂靶的设计中,需要可靠的理论计算工具精确地预言几个GeV能量范围的质子引起的散裂反应产生的各种粒子和核素。利用蒙特卡罗模拟软件包Geant4计算研究了800 MeV至3 GeV质子入射铅、铋材料引起的中子产生双微分截面。比较了Geant4不同物理模型得到的模拟结果与现有的实验数据。其中,Geant4的QGSP BERT和QGSP INCL ABLA物理模型模拟结果很好地再现了实验数据。本工作证实了Geant4蒙特卡罗模拟软件包适合用于能量高达3 GeV的质子入射铅、铋引起的中子产生双微分截面的模拟计算。 相似文献
7.
中子活化产物和辐射特征的数值模拟程序是研究材料活化效应的重要工具。在JMCT软件的基础上开发了具备材料中子活化效应模拟能力的数值模拟程序,并将其命名为“中子活化数值模拟程序”,旨在将其应用于军控核查、核安全等领域的研究中。对该程序在核弹头内部中子输运和活化计算的准确性进行了验证,发现该程序对核弹头内部中子输运和活化的计算精度优良。利用该程序研究了混凝土地面核素在裂变核材料的裂变中子辐照下的活化效应,计算结果进一步验证了中子活化数值模拟程序的功能。 相似文献
8.
9.
应用MCNPX程序,构建质子束轰击球床钨颗粒散裂靶的物理模型,模拟散裂靶泄露中子产额、能谱、通量轴向分布以及散裂靶沉积能分布。针对不同钨颗粒直径和体积填充率,研究了不同钨颗粒直径下体积填充率变化对球床散裂靶中子学特性的影响。模拟结果表明,钨颗粒体积填充率增加,散裂靶的最大沉积能密度减小。在1~20 mm的范围内,钨颗粒的直径越小,散裂靶泄漏中子产额越大,散裂靶泄漏中子产额随钨颗粒体积填充率变化的波动越小,有利于维持CIADS系统反应堆功率稳定。The physical model of the high-energy proton bombarding the tungsten pebble bed spallation target is simulated by the MCNPX program. The effect of the filling rate on the neutronic characteristics with different particle diameters is studied, by calculating the leakage neutron yield, leakage neutron spectrum axial neutron flux distribution and the energy deposition of the target. The result shows that when the diameter increases from 1 to 20 mm,the maximum deposited energy density decreases in the target, but the leakage neutron yield increases. When the filling rate reaches 74%, leakage neutron yields are almost the same value with different particle diameters. When the target is piled up with 1 mm tungsten particles, neutron leakage yield changes smaller with the variation of the filling rate than the other diameter particles which is beneficial to maintain the reactor power stability in ADS. 相似文献
10.
由中国科学院近代物理研究所负责设计和建设的加速器驱动嬗变研究装置(CiADS)将建于广东省惠州市。作为一个核装置,CiADS在运行过程中会对环境造成次级放射性影响,因此评估CiADS对环境造成的次级放射性影响水平不仅对公众健康有重要意义,对屏蔽设计也具有一定的指导作用。利用241Am-Be中子源对兰州重离子加速器研究装置(HIRFL)附近的卵石材料进行了辐照实验,测量和分析了辐照后卵石样品内产生的24Na,54Mn,56Mn和27Mg的比活度等相关信息。通过对实验数据与利用蒙特卡罗程序Geant4模拟得到的各放射性核素比活度的比较,验证了Geant4模拟分析中子场下环境介质次级放射性这一方法的可靠性。进而利用Geant4模拟研究了CiADS质子加速器HEBT隧道底部屏蔽层外的中子能谱以及隧道底部屏蔽层外卵石层因中子活化产生的主要放射性核素的饱和比活度。分析结果表明,在合理的屏蔽设计条件下,CiADS运行期间泄露到屏蔽层外的中子活化环境中卵石材料造成的环境影响几乎可以忽略。The China initiative Accelerator Driven System (CiADS) is the first integrated ADS facility designed to study the safety disposal of nuclear waste. As a nuclear facility, it will cause radiological impact on the environment. Therefore, the assessment of radiological impact on the environment around this facility will not only meaningful to the public health, but also offers significant guides to the shielding design of CiADS. Pebble samplings were collected around the campus of the Heavy Ion Research Facility in Lanzhou (HIRFL) and irradiated by a 241Am-Be neutron source. Based on the γ-spectrum measured by a HPGe detector before and after the neutron irradiation, the specific activities of induced radionuclides 24Na,54Mn,56Mn and 27Mg in these samples were analyzed and compared with the Monte-Carlo simulation values obtained with the Geant4 toolkit. The comparison between the experimental and simulated results indicates that Geant4 toolkit is feasible for radiation impact assessment of nuclear facilities, such as CiADS. Then the neutron spectrum outside the concrete shielding of HEBT tunnel of the CiADS have been simulated by the Geant4 toolkit, and the saturation activities of the induced nuclides in the first 10 cm pebble layer have been predicted. The results show that the saturation activities of induced radionuclides in pebbles outside the CiADS shielding are much lower than their exemption values and their radiation impacts to the environment could be ignored. 相似文献
11.
In an accelerator-driven subcritical system (ADS), a high-performance spallation neutron source is used to feed the subcritical reactor. Neutron generation depends on the proton beam intensity. If the beam intensity is increased by a given factor, the number of generated neutrons will increase. The mechanism yielding a high rate of neutron production per energy is the spallation process, and this mechanism produces a very high-energy deposition in the spallation target material. Producing a high rate of neutrons is accompanied by creation of problems of decay heat cooling and radiological protection. As a first step in designing a full-scale industrial ADS, a small-scale experimental ADS, which is similar to the European experimental ADS (XADS) is analysed. The analysis presented in this paper is based on lead–bismuth eutectic (LBE) cooled XADS-type experimental reactors, designed during the European experimental (PDS-XADS) project. Computational fluid dynamics analysis has been carried out for the spallation target. Steady state behaviour and shear stress transport turbulence model with the automatic wall treatment were applied in the present analysis. 相似文献
12.
13.
In pulsed spallation neutron sources, higher proton beam current or higher proton energy brings higher proton beam power, and from greater beam power come more neutrons. Consequently, accelerator scientists and target systems designers conceive systems to produce ever-higher intensities of neutrons, and the question arises: What is the best choice of proton energy to drive a pulsed spallation neutron source? Meanwhile target engineering, radiation shielding, and neutronic coupling to moderators must be accomplished effectively. This paper addresses the title question from the target side, assessing the neutron yield, the distribution of leakage neutrons, and the power density distribution as functions of proton energy. 相似文献
14.
Monitoring method for neutron flux for a spallation target in an accelerator driven sub-critical system 下载免费PDF全文
Qiang Zhao Zhi-Yong He Lei Yang Xue-Ying Zhang Wen-Juan Cui Zhi-Qiang Chen Hu-Shan Xu 《中国物理C(英文版)》2016,40(7):076203-076203
In this paper, we study a monitoring method for neutron flux for the spallation target used in an accelerator driven sub-critical(ADS) system, where a spallation target located vertically at the centre of a sub-critical core is bombarded vertically by high-energy protons from an accelerator. First, by considering the characteristics in the spatial variation of neutron flux from the spallation target, we propose a multi-point measurement technique,i.e. the spallation neutron flux should be measured at multiple vertical locations. To explain why the flux should be measured at multiple locations, we have studied neutron production from a tungsten target bombarded by a 250 Me V-proton beam with Geant 4-based Monte Carlo simulations. The simulation results indicate that the neutron flux at the central location is up to three orders of magnitude higher than the flux at lower locations. Secondly, we have developed an effective technique in order to measure the spallation neutron flux with a fission chamber(FC), by establishing the relation between the fission rate measured by FC and the spallation neutron flux. Since this relation is linear for a FC, a constant calibration factor is used to derive the neutron flux from the measured fission rate. This calibration factor can be extracted from the energy spectra of spallation neutrons. Finally, we have evaluated the proposed calibration method for a FC in the environment of an ADS system. The results indicate that the proposed method functions very well. 相似文献
15.
BARC has recently proposed a one-way coupled ADS reactor. This reactor requires typically ∼1 GeV proton beam with 2 mA of
current. Approximately 8 kW of heat is deposited in the window of the target. Circulating liquid metal target (lead/lead-bismuth-eutectic)
has to extract this heat and this is a critical R&D problem to be solved. At present there are very few accelerators, which
can give few mA and high-energy proton beam. However, accelerators with low energy and hundreds of micro-ampere current are
commercially available. In view of this, it is proposed in this paper to simulate beam window heating of ∼8 kW in the target
with low-energy proton beam. Detailed thermal analysis in the spallation and window region has been carried out to study the
capability of heat extraction by circulating LBE for a typical target loop with a proton beam of 30 MeV energy and current
of 0.267 mA. The heat deposition study is carried out using FLUKA code and flow analysis by CFD code. The detailed analysis
of this work is presented in this paper.
相似文献
16.
TANG Jing-Yu FU Shi-Nian JING Han-Tao TANG Hong-Qing WEI Jie XIA Hai-Hong 《中国物理C(英文版)》2010,34(1):121-125
The China Spallation Neutron Source (CSNS) is a large scientific facility with the main purpose of serving multidisciplinary research on material characterization using neutron scattering techniques. The accelerator system is to provide a proton beam of 120 kW with a repetition rate of 25 Hz initially (CSNSⅠ), progressively upgradeable to 240 kW (CSNS-Ⅱ) and 500 kW (CSNS-Ⅱ'). In addition to serving as a driving source for the spallation target, the proton beam can be exploited for serving additional functions both in fundamental and applied research. The expanded scientific application based on pulsed muons and fast neutrons is especially attractive in the overall consideration of CSNS upgrade options. A second target station that houses a muon-generating target and a fast-neutron-generating target in tandem, intercepting and removing a small part of the proton beam for the spallation target, is proposed. The muon and white neutron sources are operated principally in parasitic mode, leaving the main part of the beam directed to the spallation target. However, it is also possible to deliver the proton beam to the second target station in a dedicated mode for some special applications. Within the dual target configuration, the thin muon target placed upstream of the fast-neutron target will consume only about 5% of the beam traversed; the majority of the beam is used for fast-neutron production. A proton beam with a beam power of about 60 kW, an energy of 1.6 GeV and a repetition rate of 12.5 Hz will make the muon source and the white neutron source very attractive to multidisciplinary researchers. 相似文献
17.
V. I. Yurevich 《Physics of Atomic Nuclei》2016,79(2):228-235
The production of quasimonoenergetic high-energy neutrons at zero angle (0°) in the spallation of relativistic heavy nuclei is discussed by considering the example of the interaction of lead nuclei with light target nuclei. It is shown that this process can be used to generate a beam of high-energy neutrons at existing heavy ion accelerators. At the same time, itmay lead to the appearance of a parasitic neutron beam because of the interaction of the heavy-ion beam used with beam line and experimental setup materials. 相似文献
18.
《Neutron News》2012,23(2):13-16
The Rutherford Appleton Laboratory (RAL) is home to the world's leading spallation neutron source ISIS [1]. The ISIS neutron producing target is driven by a 50 Hz, 800 MeV, 200 _A proton beam from a rapid cycling synchrotron, which is fed by a 70 MeV H_ drift tube linac (DTL) which in turn accepts beam from an H_ 665 keV Cockcroft-Walton preinjector. The ever increasing international demand for neutrons has motivated a bid to build a second target station at ISIS, for which £100 million funding has recently been approved by the U.K. government [2]. The second target station, operating at 10 Hz, will provide new scientific opportunities in soft condensed matter, biology and advanced materials. 相似文献