定位格架对4×4棒束临界热流密度流体模化的影响

基于棒束临界热流密度(CHF)流体模化研究现状,进行了 4×4 棒束 CHF流体模化的实验研究。实验结果表明:适用于圆管的CHF流体模化模型不再适用于 4×4 棒束,最后一道定位格架对 4×4 棒束在氟利昂 12中的 CHF有明显的影响,表明定位格架对棒束 CHF流体模化有复杂的影响,需进一步研究。     

RELAP5对自然循环下临界热流密度的数值分析

临界热流密度(CHF)是导致沸腾传热变化而使发热元件表面发生传热恶化的现象。RELAP5等系统程序的CHF模型对于传热系统的安全分析有重要影响。基于RELAP5程序对单棒及三棒束自然循环CHF实验进行建模,并在CHF实验数据基础上对RELAP5中CHF预测值进行对比分析。实验装置是带有一个向上流动通道的自然循环回路。其中单棒束加热测试段由一根轴向非均匀加热的电加热棒及圆管外壁组成的环管状流道,三棒束流道由三根相同的轴向非均匀加热棒与三叶型的外管组成。实验条件为低压、低流量的自然循环流动:入口压力110～270 kPa、入口过冷度为10～70 K、自然循环流量0～400 kg/(m2·s)。依次以质量流量、入口压力和过冷度为基准参数对比分析实验值和RELAP5预测值。结果表明在低压、低流量及自然循环条件下,RELAP5中的CHF预测值随着质量流量的增大而增大,与入口压力及过冷度之间的依赖关系不明显。通过对实验值与模型计算值的比较得到,单棒束RELAP5模型预测的CHF值偏高于实验值,而三棒束RELAP5模型的预测值较实验值偏低。     

紧密排列棒束燃料组件临界热流密度实验研究

基于高转换比紧密布置堆芯研究背景,针对堆芯紧密排列螺旋绕肋棒束组件开展了临界热流密度(CHF)实验研究,获得了棒束在不同热工条件下临界热流密度。研究结果表明:紧密排列棒束燃料组件CHF主要发生在热棒元件,临界发生时加热元件壁面温度迅速升高,同时压力升高,流量降低;系统压力、质量流速、含汽率、入口过冷度等热工参数对组件临界热流密度影响较大;获得了CHF计算关系式,计算值与实验值偏差在±10%以内。     

高压水通过加热的正方形排列棒束时两相流动特性研究

本文介绍高压高温水通过9根正方形排列的棒束及棒束定位架时的流动阻力特性实验研究.水强迫垂直向上流过棒束.分别进行了棒束不加热的单相流动实验和棒束均匀加热并出现汽液两相流动时的两相流动实验.单相及两相实验的参数范围:P=140公斤(力)/厘米~2,质量流速 ω~g=(1.5—8)×10~6公斤/米~2小时,雷诺数 Re=3×10~3—1.5×10~5,热流密度q=(0.2—1.3)×10~6千卡/米~2·小时,平均真实含汽量(?)=0.0002—0.23.在实验研究方法上,把欠热沸腾和饱和沸腾这两种工况都看成是两相流动工况,两种工况的实验数据用真实含汽量综合成统一的实验曲线和实验关系式.在测量技术方面,采用新设计的引压装置把压差信号从高压高温实验通道测孔处引入压差计.测取的信号可靠,测量误差小.实验数据全部用计算机处理.经过综合、分析、整理后,得到棒束摩阻实验曲线和实验关系式及定位架的形阻实验曲线.     

基于低压过冷流动沸腾临界热流密度数据评价各种公式、模型及95 CHF表

以低压过冷流动沸腾的临界热流密度 (CHF)的实验数据为基础 ,对典型的CHF计算公式、模型及 95CHF表作了评价。所用数据共 2 37点 ,范围如下 :压力 0 1 3～ 1 92MPa;速度 1 4 7～2 2 32m/s;出口过冷度 6 2～ 1 0 8 7K ;加热长度 2 5 5～ 40 0mm ;管径 5 1 7～ 1 6 0mm。     

氟利昂CHF数据对压水堆工况下LUT-2006过冷CHF预测能力的评估

以R-134a为模化工质,在内径为8 mm的圆管中进行了临界热流密度（CHF）实验研究。讨论了R-134a的CHF参数变化趋势,评价了Katto的流体模化方法。结果表明,CHF仅受局部参数影响,长径比的影响可以忽略。R-134a的CHF参数趋势与典型水的CHF参数趋势相似。Katto的模化方法在低临界含气率甚至是负临界含气率下都有很高的精度。将R-134a的CHF实验数据通过模化方法转换成等效水数据,并与CHF查询表（LUT）-2006进行了比较。评价结果表明,即使在几乎没有过冷CHF数据的压水堆工况,LUT-2006仍具有很高的预测精度。      

管内流动沸腾CHF实验及氟里昂模化研究

在高温高压实验回路上进行了水在竖直管内向上流动的临界热流密度（ＣＨＦ）实验研究。共获得１１７组数据，实验参数为：压力ｐ＝６．３７～１４．７ＭＰａ；质量流速ｗ＝５７１～５４６６ｋｇ／ｍ２·ｓ，进口欠热度△ｈｉ＝９６～７４４ｋＪ／ｋｇ；出口含汽ｘｃ＝－０．０９４～０．７０２．用数学回归整理成经验关系式。该式与实验数据的总均方根偏差为５．３３％．同时，将Ａｈｍａｄ和张振杰氟里昂与水模化转换因子在应用范围内作了一些数学处理，实现了计算机快速双向模化转换，并用氟里昂和水的ＣＨＦ数据对上述两种模化方法进行了验证．结果表明，这两种模化方法都能较好地模拟单通道内水和氟里昂竖直向上流动沸腾的ＣＨＦ现象．其总均方根偏差在１０％以内。在本实验参数范围内，张振杰模化结果在数据分布和均方根偏差上稍优于Ａｈｍａｄ法．     

不同流道间隙下矩形通道临界热流密度的实验研究

在氟利昂工质条件下,进行1~3 mm间隙的矩形通道临界热流密度(CHF)的实验研究。研究发现,在1~3 mm间隙的矩形通道内,随着压力的升高,CHF稍有下降;质量流速对CHF的影响呈非单调关系,在低含汽率区随着质量流速的增大,CHF增大;在高含汽率区,随着质量流速的增大,CHF减小;临界含汽量的增加导致CHF明显降低。综合分析表明,在本实验工况参数范围内,流道间隙范围为1~3 mm的矩形通道在相同的工况参数条件下,其CHF基本不受流道间隙的影响。     

圆管临界热流密度的流体模化

为了评价现有的临界热流密度(CHF)流体模化技术,在氟里昂-12热工实验装置上完成了φ202.5圆管CHF实验。在此基础上,用不同的数据源,比较了Ahmad补偿失真模型、鲁钟琪模型、Groeneveld模型和Stevens-Kirby经验比例因子模型的预测精度和适用范围,为复杂流道中的CHF流体模化研究奠定了基础。     

弥散流沸腾传热实验研究

本文对弥散流沸腾传热的实验作了介绍。该实验范围为:压力P=2-11bar,质量流速G=94.7—189.4kg/m~2s,烧干点平衡含汽量X_(CHF)=0.35—0.93,壁面热通量Q=5.4×10~4—2.3×10~5W/m~2。用可移动的热块建立稳定的烧干后传热工况,实现了在烧干点固定时对汽相温度沿轴向变化的测量。本文通过理论分析,并由实验确定得到一个用于弥散流沸腾传热分析的蒸汽产生率公式,建立了一个轴向继承型传热模型。     

我国东南沿海城市地下建筑氡浓度分布

为了解东南沿海城市地下建筑氡浓度的分布，用固体核径迹法(SSNTD’s)，分别在春、夏、冬3季对沿海7城市地下建筑室内氡浓度进行调查。结果表明，福州具有最高的平均氡浓度，上海的平均氡浓度最低。季节的变化对地下建筑室内氡浓度有影响，各城市氡浓度平均值夏季最高、冬季最低。各城市夏季氡浓度与该城市的年均值的比值与城市中各测点氡浓度之间的离散度有一定的相关性。夏季地下建筑室内氡浓度高的城市，它的平均氡浓度受某些具有高氡水平测点的影响大。     

Fusion Safety Studies in Russia in 1996

The paper seeks to provide a summary report of observations and results of some Russian fusion safety studies performed in 1996. Release of tritium and helium from neutron irradiated beryllium at relatively high neutron fluences has a burst nature. With the growth of the beryllium temperature-increase rate to 90 K/s, the temperature of tritium burst release decreases from 800 to 450–500°C and for helium decreases from 1200 to 500°C. Characterization of carbon and tungsten dust produced in experiments simulating plasma disruptions revealed that dust particle distribution of sizes for graphites and carbon fiber composites has a bimodal nature with maxima in the range of 0.01–0.03 and 2–4 m for composite UAM and in the range of 0.14–0.18 and 2–4 m for graphite MPG-8. Chemical reactivity of beryllium with air was studied as well. A mathematical model for beryllium weight gain under its chemical interaction with air at temperatures of 700–800°C as a function of beryllium porosity, temperature, and interaction duration was developed.     

Trends in computational intelligence in nuclear engineering

Several changes to the focus of Computational Intelligence in Nuclear Engineering have occurred in the past few years. With earlier activities focusing on the development of condition monitoring and diagnostic techniques for current nuclear power plants, recent activities have focused on the implementation of those methods and the development of methods for next generation plants and space reactors. These advanced techniques are expected to become increasingly important as current generation nuclear power plants have their licenses extended to 60 years and next generation reactors are being designed to operate for extended fuel cycles (up to 25 years), with less operator oversight, and especially for nuclear plants operating in severe environments such as space or ice-bound locations.     

Increase in internal friction in uranium with change in temperature

On the basis of the previously described increase in internal friction in uranium during heating, a semiquantitative evaluation was made of the dependence of increase in internal friction on the rate of heating, frequency and amplitude of vibrations. The results of the calculations agree satisfactorily with data obtained experimentally. A study was made of the effect of the initial state of the specimen on the increase in internal friction at the initial stages of heating.     

广东省进出口食品中的放射性检验

报道了广东省商检中心放射性检验室开展的广东进出口食品中的放射性检验工作。介绍了检验工作采用仪器的主要性能及应用；给出了分析测量方法和探测下限以及实验的质量保证措施，并给出了检验室测量的广东省几种食品中的放射性含量范围，测量结果与我国食品中放射性活度变化范围大体一致。     

微机在核物理实验应用中的抗干扰问题

本文简单介绍了计算机在核物理技术应用中的各种噪声，并初步探讨了抑制噪声的方法。     

关于核材料衡算中秤重误差方差的求取

由于秤重在核材料衡算中的大量应用，如何求取秤重的随机误差方差与秤量的系统误差方差是解决核材料闭合衡算的一个重要方面。本文循序渐进讲述如何求取这两类误差的方法及步骤，以期对核材料衡算工作有一定的借鉴。     

Tritium concentrations in precipitation in Shanghai

Beamline BL17 U1 at Shanghai Synchrotron Radiation Facility is an energy-tunable macromolecular crystallography beamline that has been in user operation since 2009. Growing demand from the user community for a small beam and related experimental methods have motivated upgrades of the devices in the endstation.Minibeam modes have already been developed for operation. A self-integrated diffractometer reduces the sphere of confusion of the rotatory axis to 1μm. The new diffractometer is equipped with an upgraded on-axis viewing system that can improve the resolving power. Additionally,the area detector was also upgraded to the newest generation of detectors, the EIGER X 16 M, which can collect data at 133 Hz. After these upgrades, the endstation became virtually new. This paper covers the upgrade of the endstation devices and gives the first data collection results.     

2010年的美国铀矿业

2010年,美国铀矿总共施工7 209个钻孔,总进尺1 493 520 m;生产铀1 628.55t;铀矿业总支出费用为2.773亿美元,其中铀矿地勘费支出为3 450万美元,占铀矿业总费用的12.44％.铀矿地勘钻探费用为4 460万美元,占铀矿业总费用的16.08％.     

Temporal changes in vertical distribution of 137Cs in litter and soils in mixed deciduous forests in Fukushima,Japan

Downward migration of ¹³⁷Cs in soils was studied in three mixed deciduous forests c.a. 40 km northwest of the Fukushima Daiichi Nuclear power plant (FDNPP), Japan. We selected three different types of forest regarding to environmental condition such as slope inclinations and snow coverage conditions at the time of deposition. We examined temporal changes in the vertical distribution of ¹³⁷Cs from litter layers to 10 cm soil depth for two years (2.3 to 4.3 years after the FDNPP accident in 2011). At all three study sites, the ¹³⁷Cs in the litter layer had largely migrated to surface soil by 2013. After 2014, about 80% of the ¹³⁷Cs in forest soils (litter layer to 10 cm soil depth) remained within 0–5 cm soil layer. The vertical distribution had not changed substantially since 2014, suggesting that changes to the downward migration rates of ¹³⁷Cs in soils drastically decreased with time. In addition, small amounts of migrating ¹³⁷Cs could not be detected by the present method because there was a large spatial variation in the distribution of soil ¹³⁷Cs. The results showed similar patterns of soil ¹³⁷Cs distribution among the three study sites although there were differences in the environmental conditions.