The operation of a high-temperature fuel rod with a fuel kernel consisting of uranium dioxide is accompanied by significant changes in the initial structure of the fuel – a multi-zone dioxide structure with different grain size and shape (growth of initially uniaxial grains, formation of a columnar structure) can form in the transverse section of the kernel. For low level of stress appearing in the fuel kernel of such a fuel rod, the creep rate ξ of uranium dioxide is proportional to the stress σ(ξ ~ Bσ), where the creep coefficient B for a specified range of stress depends on the grain size. A method is described for performing reactor tests on model fuel rods that makes it possible to determine the integral coefficient of creep of a fuel kernel, which depends on the temperature distribution and the size and shape of the formed grains. The use of this coefficient greatly simplifies the computational modeling of the useful-life behavior of a high-temperature fuel rod. This method obviates the need for post-reactor studies of fuel-kernel structure. It is most effective when used in combination with neutron-diffraction analysis during irradiation for fast processing of fuel rods.

中文翻译：

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核反应堆高温二氧化铀核蠕变研究

具有由二氧化铀组成的燃料核的高温燃料棒的运行伴随着燃料初始结构的显着变化——具有不同晶粒尺寸和形状的多区二氧化结构（初始单轴晶粒的生长、形成柱状结构）可以在内核的横截面中形成。对于这种燃料棒的燃料核中出现的低应力水平，二氧化铀的蠕变速率 ξ 与应力 σ(ξ ~ Bσ) 成正比，其中指定应力范围内的蠕变系数 B 取决于晶粒尺寸。描述了一种对模型燃料棒进行反应堆测试的方法，该方法可以确定燃料核的蠕变积分系数，该系数取决于温度分布以及所形成颗粒的大小和形状。该系数的使用极大地简化了高温燃料棒使用寿命行为的计算建模。这种方法不需要对燃料-核结构进行反应堆后研究。当在辐照过程中与中子衍射分析结合使用时，它是最有效的，以快速处理燃料棒。