3D LiDAR-Based Online Monitoring of Sodium Combustion Aerosol Concentration via Regression Analysis

Sodium is used as coolant in sodium cooled fast breeder reactor (SFR). Sodium combustion aerosol detection and monitoring are key to safe management of sodium fire events in SFRs. A technique has been developed to monitor sodium combustion aerosol concentration in real-time using the Ouster 3D LiDAR (Light Detection And Ranging) module, eliminating the need for chemical methods. The module uses an array of laser light of 865 nm wavelength, which under goes scattering in presence of sodium combustion aerosol particles. An experimental set up is designed to generate Sodium Combustion Aerosol Concentration (SCAC) with varying concentration to study 3D LIDAR data response. The SCAC, ranging from $50 \mathrm{mg} / \mathrm{m}^{3}$ to $2030 \mathrm{mg} / \mathrm{m}^{3}$ is collected from enclosed chamber at regular intervals using the passive sampling method and analyzed via Ion Chromatography, with an accuracy of ± 1ppm. These concentration values are compared with acquired 3D LiDAR data. The LiDAR module generates signal photon, range, reflectivity, and IR data. Among these, signal photon and reflectivity points vary in proportion to SCAC. Two polynomial equations are derived for these two parameters from measured range of SCAC. The developed polynomial models are compared and found in close agreement ($\pm 5 \%$). Details of developed methodologies and experiments are presented in this paper.