A Review of Insulating Materials for Self-powered Neutron Detectors

Self-powered neutron detectors (SPNDs), as critical components for monitoring neutron flux in nuclear reactor cores, rely heavily on the performance of their insulating materials, which directly affects the detector’s reliability and lifespan under extreme conditions such as high temperatures and intense radiation. This paper systematically reviews recent progress in SPND insulation materials, with a focus on the performance characteristics and practical engineering applications of inorganic ceramic materials such as alumina, magnesia, silica, and beryllia, as well as organic polymer materials like polyethylene, polytetrafluoroethylene (PTFE), and polyimide. Studies indicate that inorganic materials, due to their high melting points, excellent insulation properties, and radiation resistance, are the preferred choice for high-temperature reactor core environments. In contrast, organic materials, with advantages in light weight, flexibility, and ease of processing, are better suited for low-temperature or short-duration detection scenarios. This study also analyzes the two core factors affecting insulation performance—temperature and radiation. High temperatures exacerbate grain boundary impurity diffusion in inorganic materials, leading to decreased resistivity; radiation induces defect accumulation through lattice displacement damage and ionization effects, degrading the insulation properties of inorganic materials. Organic materials are prone to chain scission and cross-linking under radiation, significantly reducing their insulation resistance. Future development will focus on optimizing a new generation of material systems with integrated performance features of high resistivity, heat resistance, and radiation tolerance, aiming to overcome current material limitations and develop higher-performance SPNDs, thereby providing critical technological support for the safe operation and accurate monitoring of advanced nuclear systems such as sodium-cooled fast reactors and molten salt reactors.