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 (L_(max)) and air-quantity of ventilation system for dummy drift(Q),section area of dummy drift(S),radon concentration of intake air(C_0),potential alpha energy of radon progeny(E_0) of intake air and radon emanation density of dummy drift(D_v) respectively,and obtains the below conclusions(i) L_(max) is decreases with increased C_0, E_0,S and D_v respectively,on the contrary increases with increased Q,(ii) when D_v= 1.463Bq/(m~3s),L_(max,Rn)=L_(max,α);when D_v1.463Bq/(m~3s),L_(max,Rn)L_(max,α);when D_v1.463Bq/(m~3s),L_(max,Rn)L_(max,α).In this paper,some optimization measures of reducing radon and its progeny are also given.