RPAS plume measurements for reconstructing radionuclide source terms

In radiological accident scenarios, one of the most important early concerns is identifying the quantity of radiological material that has been released to the environment. This work presents a rapid method of characterizing a radioactive plume through the use of a remotely piloted aircraft system (RPAS) with onboard radiation detection and geolocation sensor packages. The RPAS was flown through a research reactor Ar-41 plume, and a gamma spectrometer on board the RPAS collected radiation counts and energies in various locations within the plume, while a Global Navigation Satellite System (GNSS) module and altimeter allowed radiation data to be linked to specific positions within the plume. By combining analytical Gaussian plume dispersion models with data collected from the plume, the initial release rate was quantified. In total, thirty passes through the plume were performed, and the resulting Ar-41 release rates were found to be in good agreement with previously calculated estimates. This work demonstrates that RPAS-mounted radiation and geolocation sensor packages combined with mathematical plume reconstruction techniques are capable of providing real-time estimates of radioactive plume release rates.