Fig. 1. Deep feedforward neural network structure chart

Fig. 2. Flow chart of source term inversion calculation

Fig. 3. Comparison results between UFOTRI and ACCTRI: (a) the integral concentration of air near the ground in the downwind direction under neutral condition; (b) the ground deposition concentration in the downwind direction under neutral conditions (color online)

Fig. 4. Downwind direction near ground air integral tritium concentration of different release heights

Fig. 5. Comparison of relative error distribution between direct inversion and inversion after filtering

Fig. 6. (a) Inversion results of 20 m release height; (b) error distribution of inversion results of 20 m release height; (c) inversion results of 60 m-20 m-60 m release height; (d) error distribution of inversion results of 60 m-20 m-60 m release height

Fig. 7. Inversion results of tritium release rate with constant release rate (a) and (b); linear decrease of release rate (c) and (d); half-life decay of release rate (e) and (f)