Tritium behavior in isotropic graphite at room temperature

Abstract

For a high power proton accelerator like J-PARC (Japan Proton Accelerator Research Complex), radiation safety is a crucial issue for stable and continuous operation. Tritium is generated by a spallation process even in low-Z materials such as Be and C which are generally applied not only to target materials generating secondary particles but also to other devices irradiated by high energy particles. In general, tritium diffuses easily in a material at high temperature, goes out to the surrounding environment and eventually increases the risk of radiation safety. Thus, tritium is an issue in the maintenance work in short term, and also in storing the spent devices, especially the spent targets in long term due to tritium leakage from and accumulation in a storing container. In J-PARC, isotropic graphite is adopted as the target material for muon production, and thus it is one of the major tritium sources. The present work aims to studying tritium behavior in isotropic graphite to acquire the knowledge applicable to the facility operation.