Fukushima Daiichi Nuclear Power Plant Transfer Coefficient Matrix (TCM)
A procedure has been developed and tested to provide operational plume forecasts in real-time by continuously updating previous day's emissions as new meteorological data become available. Simulations are divided into smaller time segments and each segment is continued as an independent calculation using a unit source emission. The unit source calculations give the dispersion factors from the release point for every emission period to each downwind grid location, defining how much of the emissions are transferred to each location varying as a function of time, which is defined as the Transfer Coefficient Matrix (TCM). The TCM is computed for inert and depositing species and when quantitative air concentration results are required, the final air concentration is computed in a simple post-processing step by multiplying the TCM by the appropriate emission rate and radioactive decay constant. Results for multiple emission scenarios can easily be created and used to optimize model results as more measurement data become available.
In this online version, reported emssions of I-131 and Cs-137 from the Fukushima Daiichi Nuclear Power Plant are used to demonstrate the system. The user can adjust the reported emissions during any 6 hour release period in an attempt to improve the HYSPLIT model results of concencentrations compared to measured concentrations for any user-selected location. The user can select one of four generic species that were tracked as surrogates for the radionuclides: a gas with no wet or dry scavenging (non-depositing gas), a gas with a relatively large dry deposition velocity (0.01 m/s) and wet removal (Henry's constant = 3.00) to represent gaseous I-131 (depositing gas), a particle with a small wet deposition to represent iodine, and a particle with larger wet deposition to represent cesium, both with dry deposition of 0.004 m/s.
For a fine-scale local simulation, please visit the World Meteorological Organization (WMO) Atmospheric Dispersion Model Simulations of the Fukushima Daiichi Accident page.
Coarse Global SimulationRun the HYSPLIT Transfer Coefficient Matrix using one of the following source terms: