Fluence calculations for the TRISO- particle fuel ION implantation experiment

The TRistructural ISOtropic (TRISO) nuclear fuel is commonly used in High-Temperature Reactors (HTRs). The characteristic feature of this fuel is the presence of four covering layers. Due to the TRISO-particle fuel irradiation in the reactor core, damage in the coating layers might occur. The investigation of the damage occurring in the TRISO nuclear fuel is a key factor for the failure-free operation of HTR reactors. To determine the level of damage in the TRISO fuel, the ion implantation technique may be used. This method allows to quickly simulate the fuel irradiation phenomenon in the reactor core, through parameters such as displacements per atom (DPA). In order to determine the level of damage to the sample that corresponds to the final neutron flux of the HTR reactor, it is first necessary to determine the fluence with which the ion implantation experiment should be performed. This work aims to determine the relationship between ion fluence dose that corresponds to the neutron fluence in the HTR reactor generating similar radiation damages at the TRISO layers. For that purpose, the authors performed detailed calculations using Stopping and Range of Ions in Matter (SRIM) and Monte Carlo Continuous Energy Burn-up Code (MCB) codes. The obtained results indicate that the fluence of 3.8*1016 ions/cm2 corresponds to the neutron flux of 1.6*1013 neutrons/cm2s over one year of constant irradiation.