Simultaneous Thermal and Gamma Radiation Aging of Electrical Cable Polymers
Elevated temperature is the primary source of aging for nuclear power plant electrical cable insulation and jacketing, but gamma radiation is also a significant contributor to structural changes that result in loss of polymer mechanical and electrical properties in affected plant locations. Despite many years of research, the combined degradation effects of simultaneous exposure to thermal and radiation stresses are not well understood. As nuclear operators prepare for extended operation beyond initial license periods, a predictive understanding of exposure-based cable degradation is becoming an increasingly important input to safety, licensing, operations and economic decisions. We focus on carefully-controlled simultaneous thermal and gamma radiation aging and characterization of the most common nuclear cable polymers to understand relative contributions of temperature, time, dose and dose rate to changes in cable polymer material structure and properties. Improved understanding of cable performance in long term operation will help support continued sustainable nuclear power generation.
KeywordsCables Nuclear Polymers Thermal aging Gamma aging Simultaneous aging
Funding for this work has been provided by the Materials Aging and Degradation Pathway of the U.S. Department of Energy Office of Nuclear Energy Light Water Reactor Sustainability Program and the Nuclear Energy University Program. Data described herein was obtained with the assistance of Birgit Schwenzer, Miguel Correa, Ian Childers, Shuaishuai Liu, Mark Murphy and Andy Zwoster. The Pacific Northwest National Laboratory is operated by Battelle for the United States Department of Energy under Contract DE-AC05-76RL01830.
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