Lifetime Prediction of Fiber Optic Cable Materials for Nuclear Power Applications: Evaluation of Failure Mechanism, End of Life Criteria, and Test Methodology

摘要

This study examines important variables that must be considered while performing end of life testing for fiber optic cable materials for use in nuclear power plants. Variables investigated include selection of test temperature range, end of life criteria, identification of failure mechanism, the importance of considering competing failure mechanisms, and data analysis techniques that are used to determine lifetime limitations. Lifetime predictions are made for a variety of fiber optic cable materials including PVC (traditionally used in non-nuclear applications), Polypropylene, PBT, LSZH compounds, and other fiber optic cable materials. Differences in failure mechanisms and lifetime prediction methodologies are discussed for these various materials in terms of chemical composition and various potential failure mechanisms. Important considerations based on materials and end use are noted which differentiate test methods for fiber optic nuclear cables and tight buffer materials from test methods that have been developed for more conventional cable materials. It is demonstrated that the lifetime prediction techniques which incorporate known failure mechanisms for these materials predict practical service lifetimes for many combinations of materials that exceeds 50 years under normal service conditions.