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首页> 外文会议>Thirteenth International Symposium on Zirconium in the Nuclear Industry; Jun 10-14, 2001; Annecy, France >Variability of In-Reactor Diametral Deformation for Zr-2.5Nb Pressure Tubing
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Variability of In-Reactor Diametral Deformation for Zr-2.5Nb Pressure Tubing

机译：Zr-2.5Nb压力管反应器内径向变形的变异性

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摘要

The diametral expansion of pressure tubes in CANDU~(TM) reactors due to irradiation creep and growth is an important property that may limit the useful life of the tubes. Measurements accumulated over many years have shown that there is considerable variability in diametral strain rates between tubes. There is also considerable variability in the creep and growth response as a function of axial location, which is due to axial variations in operating temperature and flux, and to a gradual change in grain structure and crystallographic texture from one end of the tube to the other. The net effect is that pressure tubes tend to deform at a faster rate when the back end of the tube (i.e., the end leaving the extrusion press last) is installed at the fuel-channel outlet. The primary cause of the difference in microstructure along a given tube is the temperature change during the extrusion process. This end-to-end variation itself varies from tube to tube, due to variations in extrusion conditions from one extrusion run to the next, and also due to variations in ingot chemistry and billet processing. A semiempirical predictive model has been developed previously to represent the irradiation creep and growth behavior of a generic pressure tube, with a standardized microstructure, as a function of temperature and neutron flux. The diametral strain data from one hundred and twenty-five Zr-2.5Nb pressure tubes have been compared with the model. Deviations from predicted behavior have been correlated with the available microstructure, chemistry, and manufacturing data. Apart from obvious microstructural dependencies of diametral strain, such as the relationship with texture, grain structure is also a significant parameter that varies considerably from tube to tube and correlates strongly with diametral strain. The textures and grain structures, themselves, are related to manufacturing conditions (billet processing, extrusion pressures, temperatures, and soak times) and also, to some extent, on the impurity content of the material (due to the modifying effects on the Zr-Nb phase diagram).
机译：由于辐照蠕变和生长，CANDUTM反应器中压力管的直径膨胀是可能限制管的使用寿命的重要特性。多年来积累的测量结果表明，管之间的径向应变率存在很大差异。蠕变和生长响应随轴向位置的变化也存在很大差异，这是由于工作温度和通量的轴向变化以及从管的一端到另一端的晶粒结构和晶体织构的逐渐变化引起的。最终效果是，当压力管的后端（即最后离开挤压机的那一端）安装在燃料通道出口时，压力管倾向于以更快的速度变形。沿给定管的微观结构差异的主要原因是挤压过程中的温度变化。这种端到端的变化本身因管而异，这是由于从一次挤压到另一次挤压的挤压条件的变化，也是由于铸锭化学成分和坯料加工的变化。以前已经开发了一个半经验预测模型，以表示具有标准化微观结构的通用压力管的辐照蠕变和生长行为，该模型是温度和中子通量的函数。将一百二十五只Zr-2.5Nb压力管的径向应变数据与模型进行了比较。与预测行为的偏差已与可用的微观结构，化学和制造数据相关联。除了径向应变的明显的微观结构依赖性（例如与织构的关系）外，晶粒结构也是一个重要参数，管与管之间存在很大差异，并且与径向应变密切相关。质地和晶粒结构本身与制造条件（坯料加工，挤压压力，温度和保温时间）有关，并且在某种程度上还与材料的杂质含量有关（由于对Zr-的改性作用Nb相图）。

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