Quantitative visualization of a radioactive plume in a nuclear accident

Nagai, Haruyasu  ; Nakayama, Hiromasa   ; Satoh, Daiki   ; Tanimori, Toru*

A novel monitoring method for the quantitative visualization of 3D distribution of a radioactive plume accidentally released from a nuclear facility is proposed, and the feasibility of its analysis method is demonstrated by preliminary test using hypothetical data. The proposed method is the combination of gamma-ray imaging spectroscopy with the electron tracking Compton camera (ETCC) and real-time high-resolution atmospheric dispersion simulation based on 3D wind observation with Doppler lidar. ETCC can acquire the angle distribution images of direct gamma-ray from a specific radionuclide in a target radioactive plume. The 3D distribution of radioactive plume is inversely reconstructed from direct gamma-ray images by several ETCCs located around the target by harmonizing with the air concentration distribution pattern of the plume predicted by real-time atmospheric dispersion simulation. Analysis methods were developed and tested by using hypothetical data generated by numerical simulations of atmospheric dispersion and radiation transport.