核电新燃料运输容器聚氨酯泡沫填充材料寿命预测

Life prediction of polyurethane foam filled in new fuel transport cask for nuclear power

核电新燃料运输容器长期服役寿命主要受限于填充在壳体中起防震和隔热作用且不可更换的硬质聚氨酯泡沫材料。为评估填充在新燃料运输容器中的硬质聚氨酯泡沫材料的老化寿命,分别在不同温度条件下对硬质聚氨酯泡沫材料进行加速热氧老化试验,定期监测其压缩性能、颜色及微观形貌变化规律,分析其热氧老化行为。根据聚氨酯泡沫材料在不同温度下的压缩强度变化规律,获得聚氨酯泡沫材料在不同温度条件下的老化失效时间,采用阿伦尼乌斯方程外推法预测其在实际服役温度条件下的老化寿命。结果表明,聚氨酯泡沫材料适宜的热氧老化试验温度区间为100~120℃。经微观形貌观察,新燃料运输容器聚氨酯泡沫填充材料在热氧老化试验期间发生泡孔塌陷和泡孔壁破裂的现象,导致压缩强度下降。通过计算分析,在新燃料运输容器设计最高使用温度38℃条件下,预测聚氨酯泡沫材料服役寿命为54 a,能够满足30 a的设计要求。

The long-term service life of the new fuel transport cask for nuclear power is mainly limited by the non replaceable rigid polyurethane foam which is filled in the cask to prevent vibration and insulate heat.In order to evaluate the aging life of the rigid polyurethane foam filled in the new fuel transport cask,accelerated thermal oxygen aging tests were carried out on the rigid polyurethane foam under different temperature conditions,and its compression performance,appearance color and micromorphology were regularly monitored to analyze its thermal oxygen aging behavior.The aging failure time of the polyurethane foam at different temperatures was obtained according to the change rule of its compressive strength at different temperatures.The aging life of the polyurethane foam at actual service temperature was predicted by using the extrapolation method of Arrhenius equation.The results show that the suitable temperature range for thermal oxygen aging test of the polyurethane foam is 100-120℃.According to the observation of micromorphology,the polyurethane foam material filled in new fuel transport cask experiences cell collapse and cell wall rupture during the thermal oxygen aging test,which led to the decrease of compressive strength.Through calculation and analysis,when the design maximum service temperature of new fuel transport cask is 38℃,the service life of polyurethane foam material is predicted to be 54 years which can meet the design requirements of 30 years.