CABLE AGING AND CM APPROACHES BEYOND THE SHORTCOMINGS OF IAEA NUCLEAR ENERGY SERIES NO. NP-T-3.6

摘要

The purpose of this 2012 IAEA document titled "Assessing and Managing Cable Ageing in Nuclear Power Plants" was "to update certain existing IAEA publications to reflect the technical advances of the past 25 years" and "to provide guidelines on establishing cable ageing monitoring programs in new nuclear power plants." It describes a "Simplified Method" for selecting pre-aging conditions that supposedly mimic the conditions expected during ambient aging. I show that this approach typically fails for most materials since the "Simplified Method" usually results in degradation chemistry that does not reflect the chemistry operative under ambient conditions. Thus, subsequent LOCA testing will be conducted using pre-aged materials that have degradation chemistry poorly matched to ambient, usually reflecting aging nearer radiation-dominated conditions instead of nearer more thermally-dominated ambient conditions. I outline a simple and verifiable alternative approach for properly simulating ambient conditions. Further, for the many cable materials that are expected to display complex inverse-temperature effects (most EPR/EPDM and XLPE/XLPO materials), the "Simplified Method" is shown to again fail, due to the significant chemistry differences expected (and verified by Condition Monitoring techniques) between ambient aging conditions and the IAEA "Simplified Method", with the former distinctively favoring a greater scission to crosslinking ratio.