The base ANSYS case was to study the difference between having a continuous SiC phase versus discrete SiC whiskers。 The assumed geometry of the whiskers was more on the order of chopped high conductivity graphite fibers (5 microns diame-

ter × 100 microns long)。 The initial study involved comparing the best estimate case for the continuous grid FEM model to

whiskers dispersed in UO2。 The input data for the conductivity of the two phases is exactly the same (i。e。, the thermal conduc- tivity curve for UO2 was at 97%TD), and the SiC thermal con- ductivity curve comes from the previously used Starfire curve,论文网

Figure 7 A plot of the continuous and whisker SiC/UO2 thermal conductivity curves。

which assumes 70%TD。 This comparison was performed only to show the difference between continuous phase and discrete whisker geometries, similar to the case [12] for discrete particles vs。 continuous grain boundary phase。 In each case, the SiC phase occupies 10 vol % of the composite, but the physical distribution is different。

The results from the calculations displayed in Figure 7 show a difference on average of 0。4 W/m·K between the thermal con- ductivity curves。 The continuous SiC thermal model was the greater of the two, which was realistic。 This result validates that SiC whiskers in UO2 could achieve thermal conductivities near that of composite fuels with a continuous SiC phase。 Thus, the

penalty from discontinuous whiskers was not that great versus a continuous SiC phase。 When the high density of the whisker phase is inserted in the modeling, the whisker dispersed system should be superior。 When the vector plot of heat flux   flowing

through the UO2/SiC whisker composite was examined, the color-coded heat flux vectors illustrated the process in which heat conduction is accelerated through the composite by the highly conductive rectangular whiskers [20]。摘要:借助于复合材料的微观结构和界面结构，对陶瓷（氧化铀）基体中的连续第二相进行了热模拟。BeO和SiC作为第二相分散在UO2矩阵的重量对导热系数提高了0–15%,研究发现，10%的SiC，热导率从5。8增加到9。8 W/m 500 K。有限元分析、ANSYS程序用于创建和设置边界条件产生准确的热导率预测复合燃料的几何形状。结果与分析计算，此前进行的系列几何验证生产准确的热增强核燃料模型利用的效度。好的结果是发现实验测量导热系数阵和模型预测值之间相差不大。

一 简介

用于核裂变反应堆最常见的燃料二氧化铀尽管有许多可取的特点但它导热系数低。 二氧化铀的导热系数低，导致各种燃料的性能问题，如颗粒开裂，燃料搬迁，和热导率进一步下降。复合燃料的设计，能够提供更好的热性能为了极大的满足先进的反应器设计，高效率和长燃料循环的需要。在先进的测试反应器中，在棒和板的几何形状的分散燃料组成的铀和混合钚铀的不锈钢基体。[1, 2]。由一个陶瓷燃料基质中含有金属纤维均匀排列的复合燃料在过去的核反应堆矩阵中已被采用[3]。

本研究的总体目标与连续的高导电相，稳定在高的温度和中子和裂变碎片损伤氧化燃料的发展，它与氧化物燃料兼容，具有最小的中子的影响，并提供了导热系数最大的改进。改进的热传导率有许多优点，包括降低燃料的储存能量，减少辐射引起的退化，如燃料开裂，肿胀，和气体释放，和可能的功率额定值。此外，合理选择的稳定化合物可以产生高稳定性的废物形式。SiC和BeO 2材料兼容表明UO2和具有高的热传导性，[ 4，5 ]。高导电性的化合物，可以形成任一文献综述

浸渍工艺，如浸渍裂解（PIP）。例如，高密度烧结燃料中形成的碳化硅（碳化硅），具有大的开孔率；或者通过分散的晶须，这是简单的制造，虽然它可能有不连续的碳化硅相。