Study on the maximal driving length of dummy drift in uranium mines

For improving radiation condition of dummy drift in underground uranium mines, this paper expounds the mathematical description of radon concentration and potential alpha energy of its progeny in ventilation airflow, and educes the calculation formula of the maximal driving length of dummy drift for exhausting radon and its progeny. Then, this paper studies the relationships between the maximal driving length (Lmax) and air-quantity of ventilation system for dummy drift (Q), section area of dummy drift (S), radon concentration of intake air (C0), potential alpha energy of radon progeny (E0) of intake air and radon emanation density of dummy drift (Dv) respectively, and obtains the below conclusions (i) Lmax is decreases with increased C0, E0, S and Dv respectively, on the contrary increases with increased Q, (ii) when Dv=1.463 Bq/(m3s), Lmax,Rn=Lmax,α; when Dv<1.463 Bq/(m3s), Lmax,Rn>Lmax,α; when Dv>1.463 Bq/(m3s), Lmax,Rn<Lmax,α. In this paper, some optimization measures of reducing radon and its progeny are also given. (authors)