核电厂老化及老化管理

2007年3月,"欧洲核能论坛"报导了2006年该论坛在巴黎举行的关于"老化及老化管理"问题的讨论会情况。讨论会由比利时(AVN)、德国(GRS)和法国(IRSN)共同组织,交流了主要欧洲国家对付老化和处理老化问题的许多经验,颇有值得学习和借鉴之处。本文对此作了简要概括,并结合我国实践作了若干评述和补充,供有关同志参考。     

基于磁性多参数的铸造奥氏体不锈钢热老化状态评估研究

研究了应用磁性无损检测方法评估核电站主管道用铸造奥氏体不锈钢 (CASS)的热老化状态,结果表明在400 ℃下热老化不同时间,CASS的冲击功随着热老化时间延长逐渐降低,受材料组织不均应等因素影响,单一磁性参数与CASS的热老化时间之间无对应的单调规律;以磁性多参数测试为基础,结合主成分分析和非线性多元回归对测得的磁性...     

轻水堆核电站奥氏体不锈钢铸件的热老化及其老化管理

在轻水堆核电站中,奥氏体不锈钢铸件(CASS)在运行温度下长期工作将面临热老化问题。本文对热老化的机理进行了描述,并针对核电站的热老化问题,给出了老化管理工作的主要步骤,即部件敏感性甄别、老化状态评估和ISI大纲更新;结合CASS热老化的老化管理实践,对我国核电站的热老化管理工作提出了建议。     

核动力装置设备老化管理方法研究

指出了设备老化是核动力装置服役过程中不可避免的问题,它影响到核动力装置的可靠性、安全性、经济性及其寿命;给出了设备老化的概念与管理的目的;分析了设备老化的机理并详细阐述了设备老化管理的方法,指出了把老化机理研究与设备状态监测和故障诊断结合起来,采用主动性维修为主、其它运行维修策略相结合的方法对设备进行老化控制,在实际中是切实可行的．     

反应堆压力容器老化敏感性分析方法

结合近期开展的大亚湾反应堆压力容器老化分析及大纲编写工作,归纳总结了反应堆压力容器老化敏感性分析方法,提出了较为明确的表单化的老化分析流程,可以为相关的老化分析与评价活动提供借鉴.     

基于辐射原理狭窄垂直封闭空腔热阻强化措施的实验研究

列车车体围护结构中普遍存在的狭窄空腔增加了车体围护结构的热阻,同时也为进一步降低空腔的辐射换热份额创造了条件。通过实验方法,利用粘贴铝箔方式改变空腔内壁面辐射特性,以期改善空腔热工性能效果进行了研究。结果发现:常规车体壁面空腔辐射换热份额很大,不容忽视;在空腔内壁面附着铝箔等高反射率表层,可有效降低空腔的辐射换热份额,且随着空腔厚度的增大,空腔当量导热系数降低的效果更为明显,最大可达无铝箔空腔的62%左右;冷面单面粘贴铝箔方式的效果与热面单面粘贴铝箔方式的效果几乎相同,双面粘贴铝箔方式效果最好,优于单面铝箔方式5%左右。     

核设施的设备老化控制研究策略

指出了核设施中普遍存在着设备老化问题,及设备老化控制研究的必要性.探讨了分层次开展设备老化控制研究的策略及各层次的研究思路,还对运用"生命周期评价”方法开展设备老化控制研究的可行性作了探讨.     

钯的氚老化效应

钯因其显著的氢同位素效应、抗毒化及良好的固氦特性,已广泛应用于氚工艺中。随着工作时间的延长,钯中衰变产生的³He将影响其应用性能。文章就氚老化对钯的p-C-T曲线、力学性能、微观结构的影响,及³He在钯中的微观行为进行了综述。氚老化导致坪压降低、坪斜增加、氚尾增加、力学性能下降。氚衰变产生的³He聚集形成氦泡,导致晶格膨胀,且在钯中形成自间隙原子簇、位错、位错环等结构缺陷。     

ACOME电缆的老化分析

ACOME电缆主要用于大亚湾核电站保安系统中,由于电缆外护套出现了严重的增塑剂、稳定剂等助剂的析出现象,需要评估电缆的老化程度,对电缆进行了性能测试。测试结果表明:该电缆目前的性能符合一般工业用测控电缆标准,可作为一般工业用控制电缆使用,设计寿命超过30a。     

Effect of the Cu-rich precipitates on thermal conductivity of RPV model steel

Cu-rich precipitates are the important influence factors for the irradiation embrittlement of the reactor pressure vessel model steels. The microstructure of the Cu-rich precipitates could be revealed by mechanical and magnetic properties. In this article, the effect of the Cu-rich precipitates on thermal conductivity was studied. The reactor pressure vessel (RPV) model steels were aged for different time at 500°C. The results show that the thermal conductivity of RPV model steel is first decreased and then increased during the experiment, with a minimum value at 48.33 ± 0.21 W·m^?1·K^?1 after being aged for 200 h. The changing thermal conductivity is decided by the synergistic effect of the following three factors: (1) the crystal structure transformation of Cu-rich precipitates, (2) the orientation relationship between the matrix and Cu-rich precipitates, (3) the content of Cu atoms in the matrix.     

Extending the inelastic thermal spike model for semiconductors and insulators

The inelastic thermal spike framework was extended to incorporate an additional balance equation for the carrier density. Temporal and spatial evolution of carrier density, electronic and lattice temperatures were solved for silicon using a finite difference method. Calculated track radii for a range of electronic stopping powers are presented. The model allows us to fit the electron-phonon coupling to experimental data of amorphised track radii. We compare the methodology of this framework to an earlier inelastic thermal spike model, which is based on the two-temperature model for non-equilibrium processes in metals, and discuss its contribution to the understanding of microscopic processes following a swift ion irradiation event in band gap materials.     

膨润土-砂混合物缓冲层轴向热传导性研究

膨润土-砂混合物作为高放废物处置库缓冲材料,在高放废物衰变释热作用下,其物理力学性能对处置库的稳定和安全性具有重要影响。本研究采用自行设计的装置,对按比例缩小后的不同干密度、含水率、掺砂率试样进行热传导模拟试验,并对缓冲层热-力耦合过程进行数值模拟分析,得到了缓冲层温度、应力和应变的变化及分布情况,重点分析了温度的影响。结果表明,增大试样干密度、含水率和掺砂率均可提高其导热性,应变也随之增大,应力受温度影响较早达到平衡;缓冲层靠近热源的位置温度、应力和应变最大,沿轴向方向递减,初始时刻变化明显。     

Large eddy simulation of thermal striping in the upper plenum of the PGSFR

A computational study of thermal striping in the upper plenum of the prototype generation-IV sodium-cooled fast reactor (PGSFR) being developed at Korea Atomic Energy Research Institute is presented. First, previous experimental and numerical studies on the thermal striping are briefly discussed. Both Reynolds-averaged Navier–Stokes (RANS) and large eddy simulation (LES) approaches are employed for the simulation of thermal striping in the upper plenum of the PGSFR. For the RANS approach, the conventional k ? ? turbulence model is employed and the LES is performed using the wall-adapting local eddy viscosity model. From the RANS results, the time-averaged velocity components and temperature field in the complicated upper plenum of the PGSFR are calculated. In the LES results, the time history of temperature fluctuation at several locations of upper internal structure (UIS) and intermediate heat exchanger (IHX) are additionally stored. Comparisons of the predicted time-averaged velocity and temperature between the two methods show that the prediction by the LES shows faster thermal mixing than that by the k ? ? turbulence model. From the computed results of the temporal variation of temperature, it was possible to find the amplitude and frequency of the temperature fluctuation at the several locations of the UIS and IHXs. It was found that the location where the thermal stress is largest in the upper plenum of the PGSFR is the ?-shape region of the first grid plate.     

快速退火晶格恢复中瞬态增强扩散模型

本文研究了瞬态退火As注入Si的瞬态增强扩散模型。观察了增强扩散与剩余缺陷和晶格恢复之间的关系。用背散射技术测量了As浓度分布,用透射电镜观察了注入层剩余缺陷。发现在1150℃(或1050℃)退火1S晶格结构基本上恢复。在1—12s期间,缺陷密度随退火时间的增加而急剧下降。增强扩散系数在1—5s退火期间最大。在退火温度为1150℃时,退火时间在12—20s之间,注入层损伤几乎完全恢复,在此退火期间增强扩散系数比前述退火过程中的低。最后讨论了退火中晶格恢复和增强扩散机理。     

Study of doping uniformity of a 200 kV ion implanter by RBS and sheet resistance measurements

The ion implantation uniformity is of vital importance for an ion implanter.In this paper,we report the,uniformity measurement for a large current ion implanter(LC-16 type) by implanting of 190-keV Ar ions into Si to 3×1016 atoms/cm2,followed by Rutherford backscattering spectroscopy(RBS) and sheet resistance measurement providing quantitative information on spatial distribution of dopants.The implant doses obtained from RBS at selected points of the sample give a spatial uniformity of 5%,which are confirmed by the sheet resistance measurement.While sheet resistance is an indirect method for dose evaluation of ion-implanted samples,RBS provides a competent technique for calibration of the ion implantation system.And both measurements show that good uniformity can be achieved for the ion implanter by tuning of the scanning process.     

Mechanical and thermal properties of ZrSiO4

In order to conduct defueling operations for the decommissioning of the reactor at the Fukushima Daiichi nuclear power plant, an understanding of the physical properties of ZrSiO₄ is of extreme importance. ZrSiO₄ appears to have formed in the molten core–concrete interaction products at the Fukushima Daiichi nuclear disaster site through a reaction between Zircaloy cladding materials and concrete. Since ZrSiO₄ has a high melting point of 2550 K, together with chemical inertness, the material has been widely studied as a refractory material. Various studies on the physical properties of ZrSiO₄ have been performed; however, significant differences exist in the data, possibly due to the porosity within the studied samples. In the present study, we have prepared a ZrSiO₄ bulk sample with 97.4% of the theoretical density by spark plasma sintering of the ZrSiO₄ powder and heat treatment. We have evaluated the thermal and mechanical properties of ZrSiO₄ by the measurement of sound velocities, thermal diffusivity, Vickers hardness, and fracture toughness. The Vickers hardness and fracture toughness were found to be 17 ± 3 GPa and 2.1 ± 0.5 MPa m^1/2, respectively.