Study On Simulation Of Radionuclide Dispersion For Accident Condition Of Spent Fuel Storage And Transportation

Spent fuel management has become a key issue in the development of nuclear fuel cycle technology,and direct disposal,reprocessing and exportation are the three main methods,where storage and transportation play a critical role.The technologies of storage and transportation have been positively developed,however,there are some unavoidable factors of leakage from spent fuel vessel,such as cladding corrosion,technical failure,disastrous weather,impact and so on.During the spent fuel accident,the nuclear emergency decision-maker take measures to assess radiation hazard near the leakage location,so as to reduce the radiation pollution for the surrounding ecological environment caused by radionuclides dispersion.Three accident scenarios were modelled in this work,the dry storage accident,the highway transportation,and the radioactive particles resuspension and migration from the soil surface.Three Computational Fluid Dynamics(CFD)based models were developed,which were the radionuclide dispersion model of the spent fuel dry storage,the radionuclide dispersion model of the spent fuel highway transportation and the radioactive particles resuspension and migration model(RPRM),so as to analyze the distribution characteristics of radionuclides and soil radioactive particles for the real-time consequence assessment and post-accident consequence.(1)A radionuclide dispersion model of the spent fuel dry storage under accident was developed and validated,where standard k-? turbulence model was applied and updated by the consideration of the wall effect of dry storage and storage wells.In this work,the radionuclide distribution in the dry storage of spent fuel under accident condition was simulated,so as to provide more actual information for early emergency and consequence assessment.(2)A radionuclide dispersion model of the spent fuel highway transportation under accident was developed and validated,where standard k-? turbulence model was applied and updated by the consideration of the presence or absence of trees and building walls.The radionuclide distribution for the highway transportation of spent fuel under accident condition was simulated,so as to provide more actual information for the spent fuel highway transportation accident.(3)A RPRM(Radioactive Particle Resuspension and Migration)model was developed and validated,where CFD-DEM model was applied and updated by the consideration of the continuous emission,resuspension,collision,and reattachment of the radioactive particles.The soil radioactive particle distribution and migration on the non-confined backward facing step(NBFS)was simulated,so as to provide more actual information for radioactive disposal after nuclear accident.The developed models were validated to be suitable for the accidental radionuclide dispersion simulation of spent fuel storage and transportation,which lead a great improvement for the spent fuel accident radioactive consequence assessment in China.