Power Profile Reconstruction and Anomaly Detection Approach for FHRs Using Cerenkov Radiation

The optical properties of FLiBe salt in a Fluoride-Salt-Cooled High-Temperature Reactor (FHR) present an opportunity to utilize Cerenkov radiation measurements to reconstruct the power profile in the core and detect various anomalies that could occur during operation. The Cerenkov light produced within a coolant channel is strongly correlated to the fission rate density and power level in the surrounding fuel assembly and travels freely through the optically transparent salt. The light coming from coolant channels can be measured by an array of photon detectors above the channels or a system of mirrors and light guides to a detector. This allows the assembly-level power profile in the core to be reconstructed, identifying hot spots within the core. By comparing the levels of light detected to a baseline operating state, anomalies can be detected as well as their location within the core. The method has been developed and assessed computationally to realize this approach for FHRs. Details of the method and demonstrations of its applications are discussed in this paper.