Fabiani Davide, Suraci Simone Vincenzo
LIMES-Deptartment of Electrical, Electronic and Information Engineering-University of Bologna, 40136 Bologna, Italy.
National Interuniversity Consortium of Materials Science and Technology (INSTM), 50121 Florence, Italy.
Polymers (Basel). 2021 Feb 4;13(4):494. doi: 10.3390/polym13040494.
This paper deals with the study of a non-destructive technique to detect the aging state of cable insulation used in a nuclear environment subjected to radiation and temperature aging. Cable samples were aged under dose rates ranging from 0.42 and 1.06 kGy/h at 55 and 85 °C. The imaginary part of the permittivity at 100 kHz is found to correlate well with mechanical properties, such as elongation at break, which is typically used to diagnose cable insulation, but it is a destructive property and cannot be used on field. It has been demonstrated also that a post-irradiation effect occurs even years after aging is stopped, increasing the imaginary permittivity and worsening mechanical properties due to the slow conversion of radicals into oxidized species. The main consequence is that when cable insulation is subjected to a nuclear accident, releasing a huge amount of radiation, the health of cable insulation must be followed also for a long time after the accident occurred, since aging due to oxidation progresses even when the radiation source is switched off.
本文研究了一种无损检测技术，用于检测在辐射和温度老化的核环境中使用的电缆绝缘材料的老化状态。电缆样品在55℃和85℃下，剂量率范围为0.42至1.06 kGy/h的条件下进行老化。发现100 kHz下介电常数的虚部与机械性能（如断裂伸长率）具有良好的相关性，断裂伸长率通常用于诊断电缆绝缘，但它是一种破坏性性能，不能在现场使用。还证明了即使在老化停止多年后，仍会发生辐照后效应，由于自由基缓慢转化为氧化物种，导致介电常数虚部增加，机械性能恶化。主要后果是，当电缆绝缘材料遭受核事故，释放大量辐射时，即使在事故发生后很长时间，也必须持续监测电缆绝缘材料的状态，因为即使辐射源关闭，氧化老化仍会继续。
